[clang] [llvm] Enable fexec-charset option (PR #138895)

Abhina Sree via cfe-commits cfe-commits at lists.llvm.org
Thu Mar 5 05:37:36 PST 2026


https://github.com/abhina-sree updated https://github.com/llvm/llvm-project/pull/138895

>From b16517e01b77108e46cbb2941d4edacd8ef9193b Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Wed, 7 May 2025 11:26:59 -0400
Subject: [PATCH 01/15] This patch enables the fexec-charset option to control
 the execution charset of string literals. It sets the default internal
 charset, system charset, and execution charset for z/OS and UTF-8 for all
 other platforms.

(cherry picked from commit 0295d0da4db8b8fcd54084dc6ae95d8b0bbf45d9)
(cherry picked from commit e379f6cb9d063cb78c6b48b0e0a8d9f241958f89)
---
 clang/docs/LanguageExtensions.rst          |   3 +-
 clang/include/clang/Basic/LangOptions.h    |   3 +
 clang/include/clang/Basic/TokenKinds.h     |   7 ++
 clang/include/clang/Lex/LiteralConverter.h |  36 ++++++
 clang/include/clang/Lex/LiteralSupport.h   |  19 +--
 clang/include/clang/Lex/Preprocessor.h     |   3 +
 clang/include/clang/Options/Options.td     |   5 +
 clang/lib/Driver/ToolChains/Clang.cpp      |  17 ++-
 clang/lib/Frontend/CompilerInstance.cpp    |   4 +
 clang/lib/Frontend/InitPreprocessor.cpp    |  12 +-
 clang/lib/Lex/CMakeLists.txt               |   1 +
 clang/lib/Lex/LiteralConverter.cpp         |  69 +++++++++++
 clang/lib/Lex/LiteralSupport.cpp           | 133 +++++++++++++++++----
 clang/test/CodeGen/systemz-charset.c       |  35 ++++++
 clang/test/CodeGen/systemz-charset.cpp     |  46 +++++++
 clang/test/Driver/cl-options.c             |   7 +-
 clang/test/Driver/clang_f_opts.c           |  12 +-
 clang/test/Preprocessor/init-s390x.c       |   1 +
 llvm/include/llvm/TargetParser/Triple.h    |   3 +
 llvm/lib/TargetParser/Triple.cpp           |   7 ++
 20 files changed, 375 insertions(+), 48 deletions(-)
 create mode 100644 clang/include/clang/Lex/LiteralConverter.h
 create mode 100644 clang/lib/Lex/LiteralConverter.cpp
 create mode 100644 clang/test/CodeGen/systemz-charset.c
 create mode 100644 clang/test/CodeGen/systemz-charset.cpp

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 29328355c3e6f..16be538069a32 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -422,8 +422,7 @@ Builtin Macros
 ``__clang_literal_encoding__``
   Defined to a narrow string literal that represents the current encoding of
   narrow string literals, e.g., ``"hello"``. This macro typically expands to
-  "UTF-8" (but may change in the future if the
-  ``-fexec-charset="Encoding-Name"`` option is implemented.)
+  the text encoding specified by -fexec-charset if specified, or the system charset.
 
 ``__clang_wide_literal_encoding__``
   Defined to a narrow string literal that represents the current encoding of
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index ebd0436fa154b..9c2c79ff33366 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -593,6 +593,9 @@ class LangOptions : public LangOptionsBase {
   /// The allocation token mode.
   std::optional<llvm::AllocTokenMode> AllocTokenMode;
 
+  /// Name of the exec charset to convert the internal charset to.
+  std::string ExecCharset;
+
   LangOptions();
 
   /// Set language defaults for the given input language and
diff --git a/clang/include/clang/Basic/TokenKinds.h b/clang/include/clang/Basic/TokenKinds.h
index c0316257d9d97..1b2152ae518c7 100644
--- a/clang/include/clang/Basic/TokenKinds.h
+++ b/clang/include/clang/Basic/TokenKinds.h
@@ -115,6 +115,13 @@ inline bool isLiteral(TokenKind K) {
   return isInLiteralRange;
 }
 
+/// Return true if this is a utf literal kind.
+inline bool isUTFLiteral(TokenKind K) {
+  return K == tok::utf8_char_constant || K == tok::utf8_string_literal ||
+         K == tok::utf16_char_constant || K == tok::utf16_string_literal ||
+         K == tok::utf32_char_constant || K == tok::utf32_string_literal;
+}
+
 /// Return true if this is any of tok::annot_* kinds.
 bool isAnnotation(TokenKind K);
 
diff --git a/clang/include/clang/Lex/LiteralConverter.h b/clang/include/clang/Lex/LiteralConverter.h
new file mode 100644
index 0000000000000..999b2c146930f
--- /dev/null
+++ b/clang/include/clang/Lex/LiteralConverter.h
@@ -0,0 +1,36 @@
+//===--- clang/Lex/LiteralConverter.h - Translator for Literals -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LEX_LITERALCONVERTER_H
+#define LLVM_CLANG_LEX_LITERALCONVERTER_H
+
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/TargetInfo.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Support/TextEncoding.h"
+
+enum ConversionAction { NoConversion, ToSystemCharset, ToExecCharset };
+
+class LiteralConverter {
+  llvm::StringRef InternalCharset;
+  llvm::StringRef SystemCharset;
+  llvm::StringRef ExecCharset;
+  llvm::StringMap<llvm::TextEncodingConverter> TextEncodingConverters;
+
+public:
+  llvm::TextEncodingConverter *getConverter(const char *Codepage);
+  llvm::TextEncodingConverter *getConverter(ConversionAction Action);
+  llvm::TextEncodingConverter *createAndInsertCharConverter(const char *To);
+  void setConvertersFromOptions(const clang::LangOptions &Opts,
+                                const clang::TargetInfo &TInfo,
+                                clang::DiagnosticsEngine &Diags);
+};
+
+#endif
diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
index ea5f63bc20399..eaa2016c6a888 100644
--- a/clang/include/clang/Lex/LiteralSupport.h
+++ b/clang/include/clang/Lex/LiteralSupport.h
@@ -17,12 +17,13 @@
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/TokenKinds.h"
+#include "clang/Lex/LiteralConverter.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
-
+#include "llvm/Support/TextEncoding.h"
 namespace clang {
 
 class DiagnosticsEngine;
@@ -233,6 +234,7 @@ class StringLiteralParser {
   const LangOptions &Features;
   const TargetInfo &Target;
   DiagnosticsEngine *Diags;
+  LiteralConverter *LiteralConv;
 
   unsigned MaxTokenLength;
   unsigned SizeBound;
@@ -246,18 +248,19 @@ class StringLiteralParser {
   StringLiteralEvalMethod EvalMethod;
 
 public:
-  StringLiteralParser(ArrayRef<Token> StringToks, Preprocessor &PP,
-                      StringLiteralEvalMethod StringMethod =
-                          StringLiteralEvalMethod::Evaluated);
+  StringLiteralParser(
+      ArrayRef<Token> StringToks, Preprocessor &PP,
+      StringLiteralEvalMethod StringMethod = StringLiteralEvalMethod::Evaluated,
+      ConversionAction Action = ToExecCharset);
   StringLiteralParser(ArrayRef<Token> StringToks, const SourceManager &sm,
                       const LangOptions &features, const TargetInfo &target,
                       DiagnosticsEngine *diags = nullptr)
       : SM(sm), Features(features), Target(target), Diags(diags),
-        MaxTokenLength(0), SizeBound(0), CharByteWidth(0), Kind(tok::unknown),
-        ResultPtr(ResultBuf.data()),
+        LiteralConv(nullptr), MaxTokenLength(0), SizeBound(0), CharByteWidth(0),
+        Kind(tok::unknown), ResultPtr(ResultBuf.data()),
         EvalMethod(StringLiteralEvalMethod::Evaluated), hadError(false),
         Pascal(false) {
-    init(StringToks);
+    init(StringToks, NoConversion);
   }
 
   bool hadError;
@@ -305,7 +308,7 @@ class StringLiteralParser {
   static bool isValidUDSuffix(const LangOptions &LangOpts, StringRef Suffix);
 
 private:
-  void init(ArrayRef<Token> StringToks);
+  void init(ArrayRef<Token> StringToks, ConversionAction Action);
   bool CopyStringFragment(const Token &Tok, const char *TokBegin,
                           StringRef Fragment);
   void DiagnoseLexingError(SourceLocation Loc);
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 5fb83eafc6b2a..62a65d4127947 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -25,6 +25,7 @@
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Lexer.h"
+#include "clang/Lex/LiteralConverter.h"
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/ModuleLoader.h"
 #include "clang/Lex/ModuleMap.h"
@@ -222,6 +223,7 @@ class Preprocessor {
   std::unique_ptr<ScratchBuffer> ScratchBuf;
   HeaderSearch      &HeaderInfo;
   ModuleLoader      &TheModuleLoader;
+  LiteralConverter LiteralConv;
 
   /// External source of macros.
   ExternalPreprocessorSource *ExternalSource;
@@ -1299,6 +1301,7 @@ class Preprocessor {
   SelectorTable &getSelectorTable() { return Selectors; }
   Builtin::Context &getBuiltinInfo() { return *BuiltinInfo; }
   llvm::BumpPtrAllocator &getPreprocessorAllocator() { return BP; }
+  LiteralConverter &getLiteralConverter() { return LiteralConv; }
 
   void setExternalSource(ExternalPreprocessorSource *Source) {
     ExternalSource = Source;
diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td
index 40251a65f8f70..63832667aeb53 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -7670,6 +7670,11 @@ let Visibility = [CC1Option, CC1AsOption, FC1Option] in {
 def tune_cpu : Separate<["-"], "tune-cpu">,
   HelpText<"Tune for a specific cpu type">,
   MarshallingInfoString<TargetOpts<"TuneCPU">>;
+def fexec_charset : Separate<["-"], "fexec-charset">, MetaVarName<"<charset>">,
+  HelpText<"Set the execution <charset> for string and character literals. "
+           "Supported character encodings include ISO8859-1, UTF-8, IBM-1047 "
+           "and those supported by the host icu or iconv library.">,
+  MarshallingInfoString<LangOpts<"ExecCharset">>;
 def target_cpu : Separate<["-"], "target-cpu">,
   HelpText<"Target a specific cpu type">,
   MarshallingInfoString<TargetOpts<"CPU">>;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 87d4d73748940..2eeacc438bc2f 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -50,6 +50,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Path.h"
 #include "llvm/Support/Process.h"
+#include "llvm/Support/TextEncoding.h"
 #include "llvm/Support/YAMLParser.h"
 #include "llvm/TargetParser/AArch64TargetParser.h"
 #include "llvm/TargetParser/ARMTargetParserCommon.h"
@@ -7564,12 +7565,20 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                                           << value;
   }
 
-  // -fexec_charset=UTF-8 is default. Reject others
+  // Set the default fexec-charset as the system charset.
+  CmdArgs.push_back("-fexec-charset");
+  CmdArgs.push_back(Args.MakeArgString(Triple.getSystemCharset()));
   if (Arg *execCharset = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
     StringRef value = execCharset->getValue();
-    if (!value.equals_insensitive("utf-8"))
-      D.Diag(diag::err_drv_invalid_value) << execCharset->getAsString(Args)
-                                          << value;
+    llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
+        llvm::TextEncodingConverter::create("UTF-8", value.data());
+    if (ErrorOrConverter) {
+      CmdArgs.push_back("-fexec-charset");
+      CmdArgs.push_back(Args.MakeArgString(value));
+    } else {
+      D.Diag(diag::err_drv_invalid_value)
+          << execCharset->getAsString(Args) << value;
+    }
   }
 
   RenderDiagnosticsOptions(D, Args, CmdArgs);
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index cb3e6fb9688a9..976e9806cf680 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -32,6 +32,7 @@
 #include "clang/Frontend/Utils.h"
 #include "clang/Frontend/VerifyDiagnosticConsumer.h"
 #include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/LiteralConverter.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorOptions.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
@@ -544,6 +545,9 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
 
   if (GetDependencyDirectives)
     PP->setDependencyDirectivesGetter(*GetDependencyDirectives);
+
+  PP->getLiteralConverter().setConvertersFromOptions(getLangOpts(), getTarget(),
+                                                     getDiagnostics());
 }
 
 std::string
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 18c694579abdf..07c7551162cb1 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -1027,10 +1027,14 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
     }
   }
 
-  // Macros to help identify the narrow and wide character sets
-  // FIXME: clang currently ignores -fexec-charset=. If this changes,
-  // then this may need to be updated.
-  Builder.defineMacro("__clang_literal_encoding__", "\"UTF-8\"");
+  // Macros to help identify the narrow and wide character sets. This is set
+  // to fexec-charset. If fexec-charset is not specified, the default is the
+  // system charset.
+  if (!LangOpts.ExecCharset.empty())
+    Builder.defineMacro("__clang_literal_encoding__", LangOpts.ExecCharset);
+  else
+    Builder.defineMacro("__clang_literal_encoding__",
+                        TI.getTriple().getSystemCharset());
   if (TI.getTypeWidth(TI.getWCharType()) >= 32) {
     // FIXME: 32-bit wchar_t signals UTF-32. This may change
     // if -fwide-exec-charset= is ever supported.
diff --git a/clang/lib/Lex/CMakeLists.txt b/clang/lib/Lex/CMakeLists.txt
index f61737cd68021..9e38a1b8fbb44 100644
--- a/clang/lib/Lex/CMakeLists.txt
+++ b/clang/lib/Lex/CMakeLists.txt
@@ -12,6 +12,7 @@ add_clang_library(clangLex
   InitHeaderSearch.cpp
   Lexer.cpp
   LexHLSLRootSignature.cpp
+  LiteralConverter.cpp
   LiteralSupport.cpp
   MacroArgs.cpp
   MacroInfo.cpp
diff --git a/clang/lib/Lex/LiteralConverter.cpp b/clang/lib/Lex/LiteralConverter.cpp
new file mode 100644
index 0000000000000..b00f44a238ec0
--- /dev/null
+++ b/clang/lib/Lex/LiteralConverter.cpp
@@ -0,0 +1,69 @@
+//===--- LiteralConverter.cpp - Translator for String Literals -----------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Lex/LiteralConverter.h"
+#include "clang/Basic/DiagnosticDriver.h"
+
+using namespace llvm;
+
+llvm::TextEncodingConverter *
+LiteralConverter::getConverter(const char *Codepage) {
+  auto Iter = TextEncodingConverters.find(Codepage);
+  if (Iter != TextEncodingConverters.end())
+    return &Iter->second;
+  return nullptr;
+}
+
+llvm::TextEncodingConverter *
+LiteralConverter::getConverter(ConversionAction Action) {
+  StringRef CodePage;
+  if (Action == ToSystemCharset)
+    CodePage = SystemCharset;
+  else if (Action == ToExecCharset)
+    CodePage = ExecCharset;
+  else
+    CodePage = InternalCharset;
+  return getConverter(CodePage.data());
+}
+
+llvm::TextEncodingConverter *
+LiteralConverter::createAndInsertCharConverter(const char *To) {
+  const char *From = InternalCharset.data();
+  llvm::TextEncodingConverter *Converter = getConverter(To);
+  if (Converter)
+    return Converter;
+
+  ErrorOr<TextEncodingConverter> ErrorOrConverter =
+      llvm::TextEncodingConverter::create(From, To);
+  if (!ErrorOrConverter)
+    return nullptr;
+  TextEncodingConverters.insert_or_assign(StringRef(To),
+                                          std::move(*ErrorOrConverter));
+  return getConverter(To);
+}
+
+void LiteralConverter::setConvertersFromOptions(
+    const clang::LangOptions &Opts, const clang::TargetInfo &TInfo,
+    clang::DiagnosticsEngine &Diags) {
+  using namespace llvm;
+  SystemCharset = TInfo.getTriple().getSystemCharset();
+  InternalCharset = "UTF-8";
+  ExecCharset = Opts.ExecCharset.empty() ? InternalCharset : Opts.ExecCharset;
+  // Create converter between internal and system charset
+  if (InternalCharset != SystemCharset)
+    createAndInsertCharConverter(SystemCharset.data());
+
+  // Create converter between internal and exec charset specified
+  // in fexec-charset option.
+  if (InternalCharset == ExecCharset)
+    return;
+  if (!createAndInsertCharConverter(ExecCharset.data())) {
+    Diags.Report(clang::diag::err_drv_invalid_value)
+        << "-fexec-charset" << ExecCharset;
+  }
+}
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index c220821a0098f..600a308543292 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -134,7 +134,8 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
                                   FullSourceLoc Loc, unsigned CharWidth,
                                   DiagnosticsEngine *Diags,
                                   const LangOptions &Features,
-                                  StringLiteralEvalMethod EvalMethod) {
+                                  StringLiteralEvalMethod EvalMethod,
+                                  llvm::TextEncodingConverter *Converter) {
   const char *EscapeBegin = ThisTokBuf;
   bool Delimited = false;
   bool EndDelimiterFound = false;
@@ -146,6 +147,8 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
   // that would have been \", which would not have been the end of string.
   unsigned ResultChar = *ThisTokBuf++;
   char Escape = ResultChar;
+  bool Translate = true;
+  bool Invalid = false;
   switch (ResultChar) {
   // These map to themselves.
   case '\\': case '\'': case '"': case '?': break;
@@ -186,6 +189,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
     ResultChar = 11;
     break;
   case 'x': { // Hex escape.
+    Translate = false;
     ResultChar = 0;
     if (ThisTokBuf != ThisTokEnd && *ThisTokBuf == '{') {
       Delimited = true;
@@ -249,6 +253,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
   case '4': case '5': case '6': case '7': {
     // Octal escapes.
     --ThisTokBuf;
+    Translate = false;
     ResultChar = 0;
 
     // Octal escapes are a series of octal digits with maximum length 3.
@@ -334,6 +339,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
         << std::string(1, ResultChar);
     break;
   default:
+    Invalid = true;
     if (!Diags)
       break;
 
@@ -367,6 +373,15 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
     HadError = true;
   }
 
+  if (Translate && Converter) {
+    // Invalid escapes are written as '?' and then translated.
+    char ByteChar = Invalid ? '?' : ResultChar;
+    SmallString<8> ResultCharConv;
+    Converter->convert(StringRef(&ByteChar, 1), ResultCharConv);
+    assert(ResultCharConv.size() == 1 &&
+           "Char size increased after translation");
+    ResultChar = ResultCharConv[0];
+  }
   return ResultChar;
 }
 
@@ -1751,6 +1766,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   HadError = false;
 
   Kind = kind;
+  LiteralConverter *LiteralConv = &PP.getLiteralConverter();
 
   const char *TokBegin = begin;
 
@@ -1817,6 +1833,10 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
     largest_character_for_kind = 0x7Fu;
   }
 
+  llvm::TextEncodingConverter *Converter = nullptr;
+  if (!isUTFLiteral(Kind) && LiteralConv)
+    Converter = LiteralConv->getConverter(ToExecCharset);
+
   while (begin != end) {
     // Is this a span of non-escape characters?
     if (begin[0] != '\\') {
@@ -1854,6 +1874,16 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
             HadError = true;
             PP.Diag(Loc, diag::err_character_too_large);
           }
+          if (!HadError && Converter) {
+            assert(Kind != tok::wide_char_constant &&
+                   "Wide character translation not supported");
+            char ByteChar = *tmp_out_start;
+            SmallString<1> ConvertedChar;
+            Converter->convert(StringRef(&ByteChar, 1), ConvertedChar);
+            assert(ConvertedChar.size() == 1 &&
+                   "Char size increased after translation");
+            *tmp_out_start = ConvertedChar[0];
+          }
         }
       }
 
@@ -1861,16 +1891,35 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
     }
     // Is this a Universal Character Name escape?
     if (begin[1] == 'u' || begin[1] == 'U' || begin[1] == 'N') {
-      unsigned short UcnLen = 0;
-      if (!ProcessUCNEscape(TokBegin, begin, end, *buffer_begin, UcnLen,
-                            FullSourceLoc(Loc, PP.getSourceManager()),
-                            &PP.getDiagnostics(), PP.getLangOpts(), true)) {
-        HadError = true;
-      } else if (*buffer_begin > largest_character_for_kind) {
-        HadError = true;
-        PP.Diag(Loc, diag::err_character_too_large);
+      if (Converter == nullptr) {
+        unsigned short UcnLen = 0;
+        if (!ProcessUCNEscape(TokBegin, begin, end, *buffer_begin, UcnLen,
+                              FullSourceLoc(Loc, PP.getSourceManager()),
+                              &PP.getDiagnostics(), PP.getLangOpts(), true)) {
+          HadError = true;
+        } else if (*buffer_begin > largest_character_for_kind) {
+          HadError = true;
+          PP.Diag(Loc, diag::err_character_too_large);
+        }
+      } else {
+        char Cp[8];
+        char *ResultPtr = Cp;
+        unsigned CharByteWidth = 1;
+        EncodeUCNEscape(TokBegin, begin, end, ResultPtr, HadError,
+                        FullSourceLoc(Loc, PP.getSourceManager()),
+                        CharByteWidth, &PP.getDiagnostics(), PP.getLangOpts());
+        if (!HadError) {
+          SmallString<8> CpConv;
+          Converter->convert(StringRef(Cp), CpConv);
+          if (CpConv.size() > 1) {
+            HadError = true;
+            PP.Diag(Loc, diag::err_character_too_large);
+          } else {
+            memcpy(Cp, CpConv.data(), CpConv.size());
+            *buffer_begin = *Cp;
+          }
+        }
       }
-
       ++buffer_begin;
       continue;
     }
@@ -1879,7 +1928,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
         ProcessCharEscape(TokBegin, begin, end, HadError,
                           FullSourceLoc(Loc, PP.getSourceManager()), CharWidth,
                           &PP.getDiagnostics(), PP.getLangOpts(),
-                          StringLiteralEvalMethod::Evaluated);
+                          StringLiteralEvalMethod::Evaluated, nullptr);
     *buffer_begin++ = result;
   }
 
@@ -1989,16 +2038,18 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
 ///
 StringLiteralParser::StringLiteralParser(ArrayRef<Token> StringToks,
                                          Preprocessor &PP,
-                                         StringLiteralEvalMethod EvalMethod)
+                                         StringLiteralEvalMethod EvalMethod,
+                                         ConversionAction Action)
     : SM(PP.getSourceManager()), Features(PP.getLangOpts()),
       Target(PP.getTargetInfo()), Diags(&PP.getDiagnostics()),
-      MaxTokenLength(0), SizeBound(0), CharByteWidth(0), Kind(tok::unknown),
-      ResultPtr(ResultBuf.data()), EvalMethod(EvalMethod), hadError(false),
-      Pascal(false) {
-  init(StringToks);
+      LiteralConv(&PP.getLiteralConverter()), MaxTokenLength(0), SizeBound(0),
+      CharByteWidth(0), Kind(tok::unknown), ResultPtr(ResultBuf.data()),
+      EvalMethod(EvalMethod), hadError(false), Pascal(false) {
+  init(StringToks, Action);
 }
 
-void StringLiteralParser::init(ArrayRef<Token> StringToks){
+void StringLiteralParser::init(ArrayRef<Token> StringToks,
+                               ConversionAction Action) {
   // The literal token may have come from an invalid source location (e.g. due
   // to a PCH error), in which case the token length will be 0.
   if (StringToks.empty() || StringToks[0].getLength() < 2)
@@ -2090,6 +2141,10 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks){
 
   SourceLocation UDSuffixTokLoc;
 
+  llvm::TextEncodingConverter *Converter = nullptr;
+  if (!isUTFLiteral(Kind) && LiteralConv)
+    Converter = LiteralConv->getConverter(Action);
+
   for (unsigned i = 0, e = StringToks.size(); i != e; ++i) {
     const char *ThisTokBuf = &TokenBuf[0];
     // Get the spelling of the token, which eliminates trigraphs, etc.  We know
@@ -2203,6 +2258,16 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks){
         if (CopyStringFragment(StringToks[i], ThisTokBegin, BeforeCRLF))
           hadError = true;
 
+        if (!hadError && Converter) {
+          assert(Kind != tok::wide_string_literal &&
+                 "Wide character translation not supported");
+          SmallString<256> CpConv;
+          int ResultLength = BeforeCRLF.size() * CharByteWidth;
+          char *Cp = ResultPtr - ResultLength;
+          Converter->convert(StringRef(Cp, ResultLength), CpConv);
+          memcpy(Cp, CpConv.data(), ResultLength);
+          ResultPtr = Cp + CpConv.size();
+        }
         // Point into the \n inside the \r\n sequence and operate on the
         // remaining portion of the literal.
         RemainingTokenSpan = AfterCRLF.substr(1);
@@ -2237,26 +2302,45 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks){
             ++ThisTokBuf;
           } while (ThisTokBuf != ThisTokEnd && ThisTokBuf[0] != '\\');
 
+          int Length = ThisTokBuf - InStart;
           // Copy the character span over.
           if (CopyStringFragment(StringToks[i], ThisTokBegin,
                                  StringRef(InStart, ThisTokBuf - InStart)))
             hadError = true;
+
+          if (!hadError && Converter) {
+            assert(Kind != tok::wide_string_literal &&
+                   "Wide character translation not supported");
+            SmallString<256> CpConv;
+            int ResultLength = Length * CharByteWidth;
+            char *Cp = ResultPtr - ResultLength;
+            Converter->convert(StringRef(Cp, ResultLength), CpConv);
+            memcpy(Cp, CpConv.data(), ResultLength);
+            ResultPtr = Cp + CpConv.size();
+          }
           continue;
         }
         // Is this a Universal Character Name escape?
         if (ThisTokBuf[1] == 'u' || ThisTokBuf[1] == 'U' ||
             ThisTokBuf[1] == 'N') {
-          EncodeUCNEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd,
-                          ResultPtr, hadError,
+          char *Cp = ResultPtr;
+          EncodeUCNEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd, ResultPtr,
+                          hadError,
                           FullSourceLoc(StringToks[i].getLocation(), SM),
                           CharByteWidth, Diags, Features);
+          if (!hadError && Converter) {
+            SmallString<8> CpConv;
+            Converter->convert(StringRef(Cp), CpConv);
+            memcpy(Cp, CpConv.data(), CpConv.size());
+            ResultPtr = Cp + CpConv.size();
+          }
           continue;
         }
         // Otherwise, this is a non-UCN escape character.  Process it.
-        unsigned ResultChar =
-            ProcessCharEscape(ThisTokBegin, ThisTokBuf, ThisTokEnd, hadError,
-                              FullSourceLoc(StringToks[i].getLocation(), SM),
-                              CharByteWidth * 8, Diags, Features, EvalMethod);
+        unsigned ResultChar = ProcessCharEscape(
+            ThisTokBegin, ThisTokBuf, ThisTokEnd, hadError,
+            FullSourceLoc(StringToks[i].getLocation(), SM), CharByteWidth * 8,
+            Diags, Features, EvalMethod, Converter);
 
         if (CharByteWidth == 4) {
           // FIXME: Make the type of the result buffer correct instead of
@@ -2454,7 +2538,8 @@ unsigned StringLiteralParser::getOffsetOfStringByte(const Token &Tok,
     } else {
       ProcessCharEscape(SpellingStart, SpellingPtr, SpellingEnd, HadError,
                         FullSourceLoc(Tok.getLocation(), SM), CharByteWidth * 8,
-                        Diags, Features, StringLiteralEvalMethod::Evaluated);
+                        Diags, Features, StringLiteralEvalMethod::Evaluated,
+                        nullptr);
       --ByteNo;
     }
     assert(!HadError && "This method isn't valid on erroneous strings");
diff --git a/clang/test/CodeGen/systemz-charset.c b/clang/test/CodeGen/systemz-charset.c
new file mode 100644
index 0000000000000..aab43157b1be4
--- /dev/null
+++ b/clang/test/CodeGen/systemz-charset.c
@@ -0,0 +1,35 @@
+// RUN: %clang_cc1 %s -emit-llvm -triple s390x-none-zos -fexec-charset IBM-1047 -o - | FileCheck %s
+// RUN: %clang %s -emit-llvm -S -target s390x-ibm-zos -o - | FileCheck %s
+
+const char *UpperCaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
+// CHECK: c"\C1\C2\C3\C4\C5\C6\C7\C8\C9\D1\D2\D3\D4\D5\D6\D7\D8\D9\E2\E3\E4\E5\E6\E7\E8\E9\00"
+
+const char *LowerCaseLetters = "abcdefghijklmnopqrstuvwxyz";
+//CHECK: c"\81\82\83\84\85\86\87\88\89\91\92\93\94\95\96\97\98\99\A2\A3\A4\A5\A6\A7\A8\A9\00"
+
+const char *Digits = "0123456789";
+// CHECK: c"\F0\F1\F2\F3\F4\F5\F6\F7\F8\F9\00"
+
+const char *SpecialCharacters = " .<(+|&!$*);^-/,%%_>`:#@=";
+// CHECK: c"@KLMNOPZ[\\]^_`akllmnyz{|~\00"
+
+const char *EscapeCharacters = "\a\b\f\n\r\t\v\\\'\"\?";
+//CHECK: c"/\16\0C\15\0D\05\0B\E0}\7Fo\00"
+
+const char *InvalidEscape = "\y\z";
+//CHECK: c"oo\00"
+
+const char *HexCharacters = "\x12\x13\x14";
+//CHECK: c"\12\13\14\00"
+
+const char *OctalCharacters = "\141\142\143";
+//CHECK: c"abc\00"
+
+const char singleChar = 'a';
+//CHECK: i8 -127
+
+const char *UcnCharacters = "\u00E2\u00AC\U000000DF";
+//CHECK: c"B\B0Y\00"
+
+const char *Unicode = "ÿ";
+//CHECK: c"\DF\00"
diff --git a/clang/test/CodeGen/systemz-charset.cpp b/clang/test/CodeGen/systemz-charset.cpp
new file mode 100644
index 0000000000000..7e66407fd2ff1
--- /dev/null
+++ b/clang/test/CodeGen/systemz-charset.cpp
@@ -0,0 +1,46 @@
+// RUN: %clang %s -std=c++17 -emit-llvm -S -target s390x-ibm-zos -o - | FileCheck %s
+
+const char *RawString = R"(Hello\n)";
+//CHECK: c"\C8\85\93\93\96\E0\95\00"
+
+const char *MultiLineRawString = R"(
+Hello
+There)";
+//CHECK: c"\15\C8\85\93\93\96\15\E3\88\85\99\85\00"
+
+char UnicodeChar8 = u8'1';
+//CHECK: i8 49
+char16_t UnicodeChar16 = u'1';
+//CHECK: i16 49
+char32_t UnicodeChar32 = U'1';
+//CHECK: i32 49
+
+const char *EscapeCharacters8 = u8"\a\b\f\n\r\t\v\\\'\"\?";
+//CHECK: c"\07\08\0C\0A\0D\09\0B\\'\22?\00"
+
+const char16_t *EscapeCharacters16 = u"\a\b\f\n\r\t\v\\\'\"\?";
+//CHECK: [12 x i16] [i16 7, i16 8, i16 12, i16 10, i16 13, i16 9, i16 11, i16 92, i16 39, i16 34, i16 63, i16 0]
+
+const char32_t *EscapeCharacters32 = U"\a\b\f\n\r\t\v\\\'\"\?";
+//CHECK: [12 x i32] [i32 7, i32 8, i32 12, i32 10, i32 13, i32 9, i32 11, i32 92, i32 39, i32 34, i32 63, i32 0]
+
+const char *UnicodeString8 = u8"Hello";
+//CHECK: c"Hello\00"
+const char16_t *UnicodeString16 = u"Hello";
+//CHECK: [6 x i16] [i16 72, i16 101, i16 108, i16 108, i16 111, i16 0]
+const char32_t *UnicodeString32 = U"Hello";
+//CHECK: [6 x i32] [i32 72, i32 101, i32 108, i32 108, i32 111, i32 0]
+
+const char *UnicodeRawString8 = u8R"("Hello\")";
+//CHECK: c"\22Hello\\\22\00"
+const char16_t *UnicodeRawString16 = uR"("Hello\")";
+//CHECK: [9 x i16] [i16 34, i16 72, i16 101, i16 108, i16 108, i16 111, i16 92, i16 34, i16 0]
+const char32_t *UnicodeRawString32 = UR"("Hello\")";
+//CHECK: [9 x i32] [i32 34, i32 72, i32 101, i32 108, i32 108, i32 111, i32 92, i32 34, i32 0]
+
+const char *UnicodeUCNString8 = u8"\u00E2\u00AC\U000000DF";
+//CHECK: c"\C3\A2\C2\AC\C3\9F\00"
+const char16_t *UnicodeUCNString16 = u"\u00E2\u00AC\U000000DF";
+//CHECK: [4 x i16] [i16 226, i16 172, i16 223, i16 0]
+const char32_t *UnicodeUCNString32 = U"\u00E2\u00AC\U000000DF";
+//CHECK: [4 x i32] [i32 226, i32 172, i32 223, i32 0]
diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
index 9fd3ff6326dcc..b0caab09405b3 100644
--- a/clang/test/Driver/cl-options.c
+++ b/clang/test/Driver/cl-options.c
@@ -250,10 +250,11 @@
 // RUN: not %clang_cl /source-charset:utf-16 -### -- %s 2>&1 | FileCheck -check-prefix=source-charset-utf-16 %s
 // source-charset-utf-16: invalid value 'utf-16' in '/source-charset:utf-16'
 
-// /execution-charset: should warn on everything except UTF-8.
-// RUN: not %clang_cl /execution-charset:utf-16 -### -- %s 2>&1 | FileCheck -check-prefix=execution-charset-utf-16 %s
-// execution-charset-utf-16: invalid value 'utf-16' in '/execution-charset:utf-16'
+// /execution-charset: should warn on invalid charsets.
+// RUN: %clang_cl /execution-charset:invalid-charset -### -- %s 2>&1 | FileCheck -check-prefix=execution-charset-invalid %s
+// execution-charset-invalid: invalid value 'invalid-charset' in '/execution-charset:invalid-charset'
 //
+
 // RUN: %clang_cl /Umymacro -### -- %s 2>&1 | FileCheck -check-prefix=U %s
 // RUN: %clang_cl /U mymacro -### -- %s 2>&1 | FileCheck -check-prefix=U %s
 // U: "-U" "mymacro"
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index 5871f1580d6b7..d791329b6c438 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -232,8 +232,14 @@
 // RUN: not %clang -### -S -finput-charset=iso-8859-1 -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-INPUT-CHARSET %s
 // CHECK-INVALID-INPUT-CHARSET: error: invalid value 'iso-8859-1' in '-finput-charset=iso-8859-1'
 
-// RUN: not %clang -### -S -fexec-charset=iso-8859-1 -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-EXEC-CHARSET %s
-// CHECK-INVALID-EXEC-CHARSET: error: invalid value 'iso-8859-1' in '-fexec-charset=iso-8859-1'
+// RUN: %clang -### -S -fexec-charset=invalid-charset -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-INPUT-CHARSET %s
+// CHECK-INVALID-INPUT-CHARSET: error: invalid value 'invalid-charset' in '-fexec-charset=invalid-charset'
+
+// Test that we support the following exec charsets.
+// RUN: %clang -### -S -fexec-charset=UTF-8 -o /dev/null %s 2>&1 | FileCheck --check-prefix=INVALID %s
+// RUN: %clang -### -S -fexec-charset=ISO8859-1 -o /dev/null %s 2>&1 | FileCheck --check-prefix=INVALID %s
+// RUN: %clang -### -S -fexec-charset=IBM-1047 -o /dev/null %s 2>&1 | FileCheck --check-prefix=INVALID %s
+// INVALID-NOT: error: invalid value
 
 // Test that we don't error on these.
 // RUN: not %clang -### -S -Werror                                                \
@@ -247,7 +253,7 @@
 // RUN:     -fident -fno-ident                                                \
 // RUN:     -fimplicit-templates -fno-implicit-templates                      \
 // RUN:     -finput-charset=UTF-8                                             \
-// RUN:     -fexec-charset=UTF-8                                             \
+// RUN:     -fexec-charset=UTF-8                                              \
 // RUN:     -fivopts -fno-ivopts                                              \
 // RUN:     -fnon-call-exceptions -fno-non-call-exceptions                    \
 // RUN:     -fpermissive -fno-permissive                                      \
diff --git a/clang/test/Preprocessor/init-s390x.c b/clang/test/Preprocessor/init-s390x.c
index a8fbde46cbb75..9ff122def913f 100644
--- a/clang/test/Preprocessor/init-s390x.c
+++ b/clang/test/Preprocessor/init-s390x.c
@@ -206,4 +206,5 @@
 // S390X-ZOS:       #define __TOS_390__ 1
 // S390X-ZOS:       #define __TOS_MVS__ 1
 // S390X-ZOS:       #define __XPLINK__ 1
+// S390X-ZOS:       #define __clang_literal_encoding__ IBM-1047
 // S390X-ZOS-GNUXX: #define __wchar_t 1
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index a940236c6aca4..e55f67feaf2d2 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -513,6 +513,9 @@ class Triple {
   /// For example, "fooos1.2.3" would return "1.2.3".
   LLVM_ABI StringRef getEnvironmentVersionString() const;
 
+  /// getSystemCharset - Get the system charset of the triple.
+  StringRef getSystemCharset() const;
+
   /// @}
   /// @name Convenience Predicates
   /// @{
diff --git a/llvm/lib/TargetParser/Triple.cpp b/llvm/lib/TargetParser/Triple.cpp
index 0a775fda7e542..1d7650a40f76e 100644
--- a/llvm/lib/TargetParser/Triple.cpp
+++ b/llvm/lib/TargetParser/Triple.cpp
@@ -1446,6 +1446,13 @@ StringRef Triple::getOSAndEnvironmentName() const {
   return Tmp.split('-').second;                      // Strip second component
 }
 
+// System charset on z/OS is IBM-1047 and UTF-8 otherwise
+StringRef Triple::getSystemCharset() const {
+  if (getOS() == llvm::Triple::ZOS)
+    return "IBM-1047";
+  return "UTF-8";
+}
+
 static VersionTuple parseVersionFromName(StringRef Name) {
   VersionTuple Version;
   Version.tryParse(Name);

>From 13ce473e88e176c4db03bca283d20799f2f91570 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Wed, 11 Jun 2025 11:22:40 -0400
Subject: [PATCH 02/15] replace StringMap with pointer

---
 clang/docs/LanguageExtensions.rst          |  5 +-
 clang/include/clang/Basic/LangOptions.h    |  4 +-
 clang/include/clang/Lex/LiteralConverter.h | 13 ++---
 clang/include/clang/Lex/LiteralSupport.h   |  2 +-
 clang/include/clang/Options/Options.td     |  2 +-
 clang/lib/Driver/ToolChains/Clang.cpp      |  8 +--
 clang/lib/Frontend/InitPreprocessor.cpp    |  6 +-
 clang/lib/Lex/LiteralConverter.cpp         | 66 ++++++++--------------
 clang/lib/Lex/LiteralSupport.cpp           |  2 +-
 llvm/include/llvm/TargetParser/Triple.h    |  4 +-
 llvm/lib/TargetParser/Triple.cpp           |  4 +-
 11 files changed, 50 insertions(+), 66 deletions(-)

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 16be538069a32..74f78cd57bdbf 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -421,8 +421,9 @@ Builtin Macros
 
 ``__clang_literal_encoding__``
   Defined to a narrow string literal that represents the current encoding of
-  narrow string literals, e.g., ``"hello"``. This macro typically expands to
-  the text encoding specified by -fexec-charset if specified, or the system charset.
+  narrow string literals, e.g., ``"hello"``. This macro expands to the text
+  encoding specified by ``-fexec-charset`` if any, or a system-specific default
+  otherwise: ``"IBM-1047"`` on z/OS and ``"UTF-8"`` on all other systems.
 
 ``__clang_wide_literal_encoding__``
   Defined to a narrow string literal that represents the current encoding of
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
index 9c2c79ff33366..3a1ea63972d9c 100644
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -593,8 +593,8 @@ class LangOptions : public LangOptionsBase {
   /// The allocation token mode.
   std::optional<llvm::AllocTokenMode> AllocTokenMode;
 
-  /// Name of the exec charset to convert the internal charset to.
-  std::string ExecCharset;
+  /// Name of the execution encoding to convert the internal encoding to.
+  std::string ExecEncoding;
 
   LangOptions();
 
diff --git a/clang/include/clang/Lex/LiteralConverter.h b/clang/include/clang/Lex/LiteralConverter.h
index 999b2c146930f..ee489bf6ce510 100644
--- a/clang/include/clang/Lex/LiteralConverter.h
+++ b/clang/include/clang/Lex/LiteralConverter.h
@@ -16,18 +16,17 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/TextEncoding.h"
 
-enum ConversionAction { NoConversion, ToSystemCharset, ToExecCharset };
+enum ConversionAction { NoConversion, ToSystemEncoding, ToExecEncoding };
 
 class LiteralConverter {
-  llvm::StringRef InternalCharset;
-  llvm::StringRef SystemCharset;
-  llvm::StringRef ExecCharset;
-  llvm::StringMap<llvm::TextEncodingConverter> TextEncodingConverters;
+  llvm::StringRef InternalEncoding;
+  llvm::StringRef SystemEncoding;
+  llvm::StringRef ExecEncoding;
+  llvm::TextEncodingConverter *ToSystemEncodingConverter;
+  llvm::TextEncodingConverter *ToExecEncodingConverter;
 
 public:
-  llvm::TextEncodingConverter *getConverter(const char *Codepage);
   llvm::TextEncodingConverter *getConverter(ConversionAction Action);
-  llvm::TextEncodingConverter *createAndInsertCharConverter(const char *To);
   void setConvertersFromOptions(const clang::LangOptions &Opts,
                                 const clang::TargetInfo &TInfo,
                                 clang::DiagnosticsEngine &Diags);
diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
index eaa2016c6a888..af0296912b8df 100644
--- a/clang/include/clang/Lex/LiteralSupport.h
+++ b/clang/include/clang/Lex/LiteralSupport.h
@@ -251,7 +251,7 @@ class StringLiteralParser {
   StringLiteralParser(
       ArrayRef<Token> StringToks, Preprocessor &PP,
       StringLiteralEvalMethod StringMethod = StringLiteralEvalMethod::Evaluated,
-      ConversionAction Action = ToExecCharset);
+      ConversionAction Action = ToExecEncoding);
   StringLiteralParser(ArrayRef<Token> StringToks, const SourceManager &sm,
                       const LangOptions &features, const TargetInfo &target,
                       DiagnosticsEngine *diags = nullptr)
diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td
index 63832667aeb53..183c4f824897c 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -7674,7 +7674,7 @@ def fexec_charset : Separate<["-"], "fexec-charset">, MetaVarName<"<charset>">,
   HelpText<"Set the execution <charset> for string and character literals. "
            "Supported character encodings include ISO8859-1, UTF-8, IBM-1047 "
            "and those supported by the host icu or iconv library.">,
-  MarshallingInfoString<LangOpts<"ExecCharset">>;
+  MarshallingInfoString<LangOpts<"ExecEncoding">>;
 def target_cpu : Separate<["-"], "target-cpu">,
   HelpText<"Target a specific cpu type">,
   MarshallingInfoString<TargetOpts<"CPU">>;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 2eeacc438bc2f..24d75ffc93aa2 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7567,9 +7567,9 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   // Set the default fexec-charset as the system charset.
   CmdArgs.push_back("-fexec-charset");
-  CmdArgs.push_back(Args.MakeArgString(Triple.getSystemCharset()));
-  if (Arg *execCharset = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
-    StringRef value = execCharset->getValue();
+  CmdArgs.push_back(Args.MakeArgString(Triple.getDefaultTextEncoding()));
+  if (Arg *execEncoding = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
+    StringRef value = execEncoding->getValue();
     llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
         llvm::TextEncodingConverter::create("UTF-8", value.data());
     if (ErrorOrConverter) {
@@ -7577,7 +7577,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back(Args.MakeArgString(value));
     } else {
       D.Diag(diag::err_drv_invalid_value)
-          << execCharset->getAsString(Args) << value;
+          << execEncoding->getAsString(Args) << value;
     }
   }
 
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 07c7551162cb1..dda530f286173 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -1030,11 +1030,11 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
   // Macros to help identify the narrow and wide character sets. This is set
   // to fexec-charset. If fexec-charset is not specified, the default is the
   // system charset.
-  if (!LangOpts.ExecCharset.empty())
-    Builder.defineMacro("__clang_literal_encoding__", LangOpts.ExecCharset);
+  if (!LangOpts.ExecEncoding.empty())
+    Builder.defineMacro("__clang_literal_encoding__", LangOpts.ExecEncoding);
   else
     Builder.defineMacro("__clang_literal_encoding__",
-                        TI.getTriple().getSystemCharset());
+                        TI.getTriple().getDefaultTextEncoding());
   if (TI.getTypeWidth(TI.getWCharType()) >= 32) {
     // FIXME: 32-bit wchar_t signals UTF-32. This may change
     // if -fwide-exec-charset= is ever supported.
diff --git a/clang/lib/Lex/LiteralConverter.cpp b/clang/lib/Lex/LiteralConverter.cpp
index b00f44a238ec0..e9f8981336e8e 100644
--- a/clang/lib/Lex/LiteralConverter.cpp
+++ b/clang/lib/Lex/LiteralConverter.cpp
@@ -11,59 +11,43 @@
 
 using namespace llvm;
 
-llvm::TextEncodingConverter *
-LiteralConverter::getConverter(const char *Codepage) {
-  auto Iter = TextEncodingConverters.find(Codepage);
-  if (Iter != TextEncodingConverters.end())
-    return &Iter->second;
-  return nullptr;
-}
-
 llvm::TextEncodingConverter *
 LiteralConverter::getConverter(ConversionAction Action) {
-  StringRef CodePage;
-  if (Action == ToSystemCharset)
-    CodePage = SystemCharset;
-  else if (Action == ToExecCharset)
-    CodePage = ExecCharset;
+  if (Action == ToSystemEncoding)
+    return ToSystemEncodingConverter;
+  else if (Action == ToExecEncoding)
+    return ToExecEncodingConverter;
   else
-    CodePage = InternalCharset;
-  return getConverter(CodePage.data());
-}
-
-llvm::TextEncodingConverter *
-LiteralConverter::createAndInsertCharConverter(const char *To) {
-  const char *From = InternalCharset.data();
-  llvm::TextEncodingConverter *Converter = getConverter(To);
-  if (Converter)
-    return Converter;
-
-  ErrorOr<TextEncodingConverter> ErrorOrConverter =
-      llvm::TextEncodingConverter::create(From, To);
-  if (!ErrorOrConverter)
     return nullptr;
-  TextEncodingConverters.insert_or_assign(StringRef(To),
-                                          std::move(*ErrorOrConverter));
-  return getConverter(To);
 }
 
 void LiteralConverter::setConvertersFromOptions(
     const clang::LangOptions &Opts, const clang::TargetInfo &TInfo,
     clang::DiagnosticsEngine &Diags) {
   using namespace llvm;
-  SystemCharset = TInfo.getTriple().getSystemCharset();
-  InternalCharset = "UTF-8";
-  ExecCharset = Opts.ExecCharset.empty() ? InternalCharset : Opts.ExecCharset;
-  // Create converter between internal and system charset
-  if (InternalCharset != SystemCharset)
-    createAndInsertCharConverter(SystemCharset.data());
+  InternalEncoding = "UTF-8";
+  SystemEncoding = TInfo.getTriple().getDefaultTextEncoding();
+  ExecEncoding =
+      Opts.ExecEncoding.empty() ? InternalEncoding : Opts.ExecEncoding;
+  // Create converter between internal and system encoding
+  if (InternalEncoding != SystemEncoding) {
+    ErrorOr<TextEncodingConverter> ErrorOrConverter =
+        llvm::TextEncodingConverter::create(InternalEncoding, SystemEncoding);
+    if (!ErrorOrConverter)
+      return;
+    ToSystemEncodingConverter =
+        new TextEncodingConverter(std::move(*ErrorOrConverter));
+  }
 
-  // Create converter between internal and exec charset specified
+  // Create converter between internal and exec encoding specified
   // in fexec-charset option.
-  if (InternalCharset == ExecCharset)
+  if (InternalEncoding == ExecEncoding)
     return;
-  if (!createAndInsertCharConverter(ExecCharset.data())) {
+  ErrorOr<TextEncodingConverter> ErrorOrConverter =
+      llvm::TextEncodingConverter::create(InternalEncoding, ExecEncoding);
+  if (!ErrorOrConverter)
     Diags.Report(clang::diag::err_drv_invalid_value)
-        << "-fexec-charset" << ExecCharset;
-  }
+        << "-fexec-charset" << ExecEncoding;
+  ToExecEncodingConverter =
+      new TextEncodingConverter(std::move(*ErrorOrConverter));
 }
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 600a308543292..55d9aced73ad0 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1835,7 +1835,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
 
   llvm::TextEncodingConverter *Converter = nullptr;
   if (!isUTFLiteral(Kind) && LiteralConv)
-    Converter = LiteralConv->getConverter(ToExecCharset);
+    Converter = LiteralConv->getConverter(ToExecEncoding);
 
   while (begin != end) {
     // Is this a span of non-escape characters?
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index e55f67feaf2d2..b88200eb0cf27 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -513,8 +513,8 @@ class Triple {
   /// For example, "fooos1.2.3" would return "1.2.3".
   LLVM_ABI StringRef getEnvironmentVersionString() const;
 
-  /// getSystemCharset - Get the system charset of the triple.
-  StringRef getSystemCharset() const;
+  /// getDefaultTextEncoding - Get the default encoding of the triple.
+  StringRef getDefaultTextEncoding() const;
 
   /// @}
   /// @name Convenience Predicates
diff --git a/llvm/lib/TargetParser/Triple.cpp b/llvm/lib/TargetParser/Triple.cpp
index 1d7650a40f76e..b10421dc9dfae 100644
--- a/llvm/lib/TargetParser/Triple.cpp
+++ b/llvm/lib/TargetParser/Triple.cpp
@@ -1446,8 +1446,8 @@ StringRef Triple::getOSAndEnvironmentName() const {
   return Tmp.split('-').second;                      // Strip second component
 }
 
-// System charset on z/OS is IBM-1047 and UTF-8 otherwise
-StringRef Triple::getSystemCharset() const {
+// Default encoding on z/OS is IBM-1047 and UTF-8 otherwise
+StringRef Triple::getDefaultTextEncoding() const {
   if (getOS() == llvm::Triple::ZOS)
     return "IBM-1047";
   return "UTF-8";

>From 94d0ff2f2e304e4a4701c89b354e3cd4a98938bc Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Tue, 21 Oct 2025 09:12:02 -0400
Subject: [PATCH 03/15] do not translate line/digit directives, do not
 translate filename

---
 clang/lib/Frontend/FrontendAction.cpp | 4 +++-
 clang/lib/Lex/PPDirectives.cpp        | 6 ++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Frontend/FrontendAction.cpp b/clang/lib/Frontend/FrontendAction.cpp
index 79e862f01be14..ee33e30afdfb0 100644
--- a/clang/lib/Frontend/FrontendAction.cpp
+++ b/clang/lib/Frontend/FrontendAction.cpp
@@ -525,7 +525,9 @@ static SourceLocation ReadOriginalFileName(CompilerInstance &CI,
   if (T.isAtStartOfLine() || T.getKind() != tok::string_literal)
     return SourceLocation();
 
-  StringLiteralParser Literal(T, CI.getPreprocessor());
+  StringLiteralParser Literal(T, CI.getPreprocessor(),
+                              StringLiteralEvalMethod::Evaluated,
+                              CA_NoConversion);
   if (Literal.hadError)
     return SourceLocation();
   RawLexer->LexFromRawLexer(T);
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 85edbabf09ed3..866cc7e728064 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -1646,7 +1646,8 @@ void Preprocessor::HandleLineDirective() {
     return;
   } else {
     // Parse and validate the string, converting it into a unique ID.
-    StringLiteralParser Literal(StrTok, *this);
+    StringLiteralParser Literal(
+        StrTok, *this, StringLiteralEvalMethod::Evaluated, CA_NoConversion);
     assert(Literal.isOrdinary() && "Didn't allow wide strings in");
     if (Literal.hadError) {
       DiscardUntilEndOfDirective();
@@ -1797,7 +1798,8 @@ void Preprocessor::HandleDigitDirective(Token &DigitTok) {
     return;
   } else {
     // Parse and validate the string, converting it into a unique ID.
-    StringLiteralParser Literal(StrTok, *this);
+    StringLiteralParser Literal(
+        StrTok, *this, StringLiteralEvalMethod::Evaluated, CA_NoConversion);
     assert(Literal.isOrdinary() && "Didn't allow wide strings in");
     if (Literal.hadError) {
       DiscardUntilEndOfDirective();

>From 2e5d6a00e85c487f6cdaaa5a4d2b93188fbdd92b Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Fri, 17 Oct 2025 12:14:09 -0400
Subject: [PATCH 04/15] address comments

---
 .../clang/Basic/DiagnosticFrontendKinds.td    |  3 +-
 .../include/clang/Basic/DiagnosticLexKinds.td |  2 +
 clang/include/clang/Basic/TokenKinds.h        |  7 ++-
 clang/include/clang/Lex/LiteralConverter.h    | 17 +++---
 clang/include/clang/Lex/LiteralSupport.h      |  4 +-
 clang/include/clang/Options/Options.td        | 13 +++--
 clang/lib/Driver/ToolChains/Clang.cpp         | 26 +++++----
 clang/lib/Frontend/CompilerInstance.cpp       |  5 +-
 clang/lib/Frontend/InitPreprocessor.cpp       |  2 +-
 clang/lib/Lex/LiteralConverter.cpp            | 53 +++++++++++--------
 clang/lib/Lex/LiteralSupport.cpp              | 44 ++++++++++-----
 clang/test/Driver/cl-options.c                |  2 +-
 clang/test/Driver/clang_f_opts.c              | 18 ++++---
 llvm/include/llvm/Support/TextEncoding.h      |  3 ++
 llvm/include/llvm/TargetParser/Triple.h       |  4 +-
 llvm/lib/Support/TextEncoding.cpp             |  3 +-
 llvm/lib/TargetParser/Triple.cpp              |  2 +-
 17 files changed, 131 insertions(+), 77 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 5c62bb70ebd0f..78677396eeab1 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -338,7 +338,8 @@ def err_non_default_visibility_dllimport : Error<
   "non-default visibility cannot be applied to 'dllimport' declaration">;
 def err_ifunc_resolver_return : Error<
   "ifunc resolver function must return a pointer">;
-
+def err_fe_literal_conv_config : Error<
+  "failed to configure the literal converter">;
 def warn_atomic_op_misaligned : Warning<
   "misaligned atomic operation may incur "
   "significant performance penalty"
diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index 77feea9f869e9..2d239a7880ac8 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -287,6 +287,8 @@ def ext_string_too_long : Extension<"string literal of length %0 exceeds "
   "support">, InGroup<OverlengthStrings>;
 def err_character_too_large : Error<
   "character too large for enclosing character literal type">;
+def err_exec_charset_conversion_failed : Error<
+  "conversion to execution encoding failed: '%0'">;
 def warn_c99_compat_unicode_literal : Warning<
   "unicode literals are incompatible with C99">,
   InGroup<C99Compat>, DefaultIgnore;
diff --git a/clang/include/clang/Basic/TokenKinds.h b/clang/include/clang/Basic/TokenKinds.h
index 1b2152ae518c7..a18b81c4dcc26 100644
--- a/clang/include/clang/Basic/TokenKinds.h
+++ b/clang/include/clang/Basic/TokenKinds.h
@@ -115,13 +115,18 @@ inline bool isLiteral(TokenKind K) {
   return isInLiteralRange;
 }
 
-/// Return true if this is a utf literal kind.
+/// Return true if this is a UTF literal kind.
 inline bool isUTFLiteral(TokenKind K) {
   return K == tok::utf8_char_constant || K == tok::utf8_string_literal ||
          K == tok::utf16_char_constant || K == tok::utf16_string_literal ||
          K == tok::utf32_char_constant || K == tok::utf32_string_literal;
 }
 
+/// Return true if this is a wide literal kind.
+inline bool isWideLiteral(TokenKind K) {
+  return K == tok::wide_char_constant || K == tok::wide_string_literal;
+}
+
 /// Return true if this is any of tok::annot_* kinds.
 bool isAnnotation(TokenKind K);
 
diff --git a/clang/include/clang/Lex/LiteralConverter.h b/clang/include/clang/Lex/LiteralConverter.h
index ee489bf6ce510..6a66d2d0ff707 100644
--- a/clang/include/clang/Lex/LiteralConverter.h
+++ b/clang/include/clang/Lex/LiteralConverter.h
@@ -16,20 +16,25 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/TextEncoding.h"
 
-enum ConversionAction { NoConversion, ToSystemEncoding, ToExecEncoding };
+enum ConversionAction {
+  CA_NoConversion,
+  CA_ToSystemEncoding,
+  CA_ToExecEncoding
+};
 
 class LiteralConverter {
   llvm::StringRef InternalEncoding;
   llvm::StringRef SystemEncoding;
   llvm::StringRef ExecEncoding;
-  llvm::TextEncodingConverter *ToSystemEncodingConverter;
-  llvm::TextEncodingConverter *ToExecEncodingConverter;
+  llvm::TextEncodingConverter *ToSystemEncodingConverter = nullptr;
+  llvm::TextEncodingConverter *ToExecEncodingConverter = nullptr;
 
 public:
   llvm::TextEncodingConverter *getConverter(ConversionAction Action);
-  void setConvertersFromOptions(const clang::LangOptions &Opts,
-                                const clang::TargetInfo &TInfo,
-                                clang::DiagnosticsEngine &Diags);
+  static std::error_code
+  setConvertersFromOptions(LiteralConverter &LiteralConv,
+                           const clang::LangOptions &Opts,
+                           const clang::TargetInfo &TInfo);
 };
 
 #endif
diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
index af0296912b8df..32ae829096592 100644
--- a/clang/include/clang/Lex/LiteralSupport.h
+++ b/clang/include/clang/Lex/LiteralSupport.h
@@ -251,7 +251,7 @@ class StringLiteralParser {
   StringLiteralParser(
       ArrayRef<Token> StringToks, Preprocessor &PP,
       StringLiteralEvalMethod StringMethod = StringLiteralEvalMethod::Evaluated,
-      ConversionAction Action = ToExecEncoding);
+      ConversionAction Action = CA_ToExecEncoding);
   StringLiteralParser(ArrayRef<Token> StringToks, const SourceManager &sm,
                       const LangOptions &features, const TargetInfo &target,
                       DiagnosticsEngine *diags = nullptr)
@@ -260,7 +260,7 @@ class StringLiteralParser {
         Kind(tok::unknown), ResultPtr(ResultBuf.data()),
         EvalMethod(StringLiteralEvalMethod::Evaluated), hadError(false),
         Pascal(false) {
-    init(StringToks, NoConversion);
+    init(StringToks, CA_NoConversion);
   }
 
   bool hadError;
diff --git a/clang/include/clang/Options/Options.td b/clang/include/clang/Options/Options.td
index 183c4f824897c..a343eaa32117a 100644
--- a/clang/include/clang/Options/Options.td
+++ b/clang/include/clang/Options/Options.td
@@ -3075,7 +3075,10 @@ def fexperimental_strict_floating_point : Flag<["-"], "fexperimental-strict-floa
 def finput_charset_EQ : Joined<["-"], "finput-charset=">,
   Visibility<[ClangOption, FlangOption, FC1Option]>, Group<f_Group>,
   HelpText<"Specify the default character set for source files">;
-def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>;
+def fexec_charset_EQ : Joined<["-"], "fexec-charset=">, Group<f_Group>,
+  HelpText<"Set the execution <charset> for string and character literals. "
+           "Supported character encodings include ISO-8859-1, UTF-8, IBM1047, "
+           "and possibly those supported by ICU or the host iconv library.">;
 def finstrument_functions
     : Flag<["-"], "finstrument-functions">,
       Group<f_Group>,
@@ -7672,8 +7675,8 @@ def tune_cpu : Separate<["-"], "tune-cpu">,
   MarshallingInfoString<TargetOpts<"TuneCPU">>;
 def fexec_charset : Separate<["-"], "fexec-charset">, MetaVarName<"<charset>">,
   HelpText<"Set the execution <charset> for string and character literals. "
-           "Supported character encodings include ISO8859-1, UTF-8, IBM-1047 "
-           "and those supported by the host icu or iconv library.">,
+           "Supported character encodings include ISO-8859-1, UTF-8, IBM1047, "
+           "and possibly those supported by ICU or the host iconv library.">,
   MarshallingInfoString<LangOpts<"ExecEncoding">>;
 def target_cpu : Separate<["-"], "target-cpu">,
   HelpText<"Target a specific cpu type">,
@@ -9315,7 +9318,9 @@ def _SLASH_source_charset : CLCompileJoined<"source-charset:">,
   HelpText<"Set source encoding, supports only UTF-8">,
   Alias<finput_charset_EQ>;
 def _SLASH_execution_charset : CLCompileJoined<"execution-charset:">,
-  HelpText<"Set runtime encoding, supports only UTF-8">,
+  HelpText<"Set the execution <charset> for string and character literals. "
+           "Supported character encodings include ISO-8859-1, UTF-8, IBM1047, "
+           "and possibly those supported by ICU or the host iconv library.">,
   Alias<fexec_charset_EQ>;
 def _SLASH_std : CLCompileJoined<"std:">,
   HelpText<"Set language version (c++14,c++17,c++20,c++23preview,c++latest,c11,c17)">;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 24d75ffc93aa2..631fe204cdd22 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7565,20 +7565,24 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                                           << value;
   }
 
-  // Set the default fexec-charset as the system charset.
-  CmdArgs.push_back("-fexec-charset");
-  CmdArgs.push_back(Args.MakeArgString(Triple.getDefaultTextEncoding()));
   if (Arg *execEncoding = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
     StringRef value = execEncoding->getValue();
-    llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
-        llvm::TextEncodingConverter::create("UTF-8", value.data());
-    if (ErrorOrConverter) {
-      CmdArgs.push_back("-fexec-charset");
-      CmdArgs.push_back(Args.MakeArgString(value));
-    } else {
-      D.Diag(diag::err_drv_invalid_value)
-          << execEncoding->getAsString(Args) << value;
+    bool KnownEncoding =
+        llvm::TextEncodingConverter::getKnownEncoding(value).has_value();
+    if (!KnownEncoding) {
+      llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
+          llvm::TextEncodingConverter::create("UTF-8", value.data());
+      if (!ErrorOrConverter)
+        D.Diag(diag::err_drv_invalid_value)
+            << execEncoding->getAsString(Args) << value;
     }
+    CmdArgs.push_back("-fexec-charset");
+    CmdArgs.push_back(Args.MakeArgString(value));
+  } else {
+    // Set the default fexec-charset as the system charset.
+    CmdArgs.push_back("-fexec-charset");
+    CmdArgs.push_back(
+        Args.MakeArgString(Triple.getDefaultNarrowTextEncoding()));
   }
 
   RenderDiagnosticsOptions(D, Args, CmdArgs);
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 976e9806cf680..c151d18e7e05e 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -546,8 +546,9 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
   if (GetDependencyDirectives)
     PP->setDependencyDirectivesGetter(*GetDependencyDirectives);
 
-  PP->getLiteralConverter().setConvertersFromOptions(getLangOpts(), getTarget(),
-                                                     getDiagnostics());
+  if (!LiteralConverter::setConvertersFromOptions(PP->getLiteralConverter(),
+                                                  getLangOpts(), getTarget()))
+    PP->getDiagnostics().Report(clang::diag::err_fe_literal_conv_config);
 }
 
 std::string
diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index dda530f286173..ee43c2552dc4a 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -1034,7 +1034,7 @@ static void InitializePredefinedMacros(const TargetInfo &TI,
     Builder.defineMacro("__clang_literal_encoding__", LangOpts.ExecEncoding);
   else
     Builder.defineMacro("__clang_literal_encoding__",
-                        TI.getTriple().getDefaultTextEncoding());
+                        TI.getTriple().getDefaultNarrowTextEncoding());
   if (TI.getTypeWidth(TI.getWCharType()) >= 32) {
     // FIXME: 32-bit wchar_t signals UTF-32. This may change
     // if -fwide-exec-charset= is ever supported.
diff --git a/clang/lib/Lex/LiteralConverter.cpp b/clang/lib/Lex/LiteralConverter.cpp
index e9f8981336e8e..2bd177d499b87 100644
--- a/clang/lib/Lex/LiteralConverter.cpp
+++ b/clang/lib/Lex/LiteralConverter.cpp
@@ -13,41 +13,48 @@ using namespace llvm;
 
 llvm::TextEncodingConverter *
 LiteralConverter::getConverter(ConversionAction Action) {
-  if (Action == ToSystemEncoding)
+  if (Action == CA_ToSystemEncoding)
     return ToSystemEncodingConverter;
-  else if (Action == ToExecEncoding)
+  else if (Action == CA_ToExecEncoding)
     return ToExecEncodingConverter;
   else
     return nullptr;
 }
 
-void LiteralConverter::setConvertersFromOptions(
-    const clang::LangOptions &Opts, const clang::TargetInfo &TInfo,
-    clang::DiagnosticsEngine &Diags) {
+std::error_code
+LiteralConverter::setConvertersFromOptions(LiteralConverter &LiteralConv,
+                                           const clang::LangOptions &Opts,
+                                           const clang::TargetInfo &TInfo) {
   using namespace llvm;
-  InternalEncoding = "UTF-8";
-  SystemEncoding = TInfo.getTriple().getDefaultTextEncoding();
-  ExecEncoding =
-      Opts.ExecEncoding.empty() ? InternalEncoding : Opts.ExecEncoding;
+  LiteralConv.InternalEncoding = "UTF-8";
+  LiteralConv.SystemEncoding = TInfo.getTriple().getDefaultNarrowTextEncoding();
+  LiteralConv.ExecEncoding = Opts.ExecEncoding.empty()
+                                 ? LiteralConv.InternalEncoding
+                                 : Opts.ExecEncoding;
+
   // Create converter between internal and system encoding
-  if (InternalEncoding != SystemEncoding) {
+  if (LiteralConv.InternalEncoding != LiteralConv.SystemEncoding) {
     ErrorOr<TextEncodingConverter> ErrorOrConverter =
-        llvm::TextEncodingConverter::create(InternalEncoding, SystemEncoding);
-    if (!ErrorOrConverter)
-      return;
-    ToSystemEncodingConverter =
-        new TextEncodingConverter(std::move(*ErrorOrConverter));
+        llvm::TextEncodingConverter::create(LiteralConv.InternalEncoding,
+                                            LiteralConv.SystemEncoding);
+    if (ErrorOrConverter) {
+      LiteralConv.ToSystemEncodingConverter =
+          new TextEncodingConverter(std::move(*ErrorOrConverter));
+    } else
+      return ErrorOrConverter.getError();
   }
 
   // Create converter between internal and exec encoding specified
   // in fexec-charset option.
-  if (InternalEncoding == ExecEncoding)
-    return;
+  if (LiteralConv.InternalEncoding == LiteralConv.ExecEncoding)
+    return std::error_code();
   ErrorOr<TextEncodingConverter> ErrorOrConverter =
-      llvm::TextEncodingConverter::create(InternalEncoding, ExecEncoding);
-  if (!ErrorOrConverter)
-    Diags.Report(clang::diag::err_drv_invalid_value)
-        << "-fexec-charset" << ExecEncoding;
-  ToExecEncodingConverter =
-      new TextEncodingConverter(std::move(*ErrorOrConverter));
+      llvm::TextEncodingConverter::create(LiteralConv.InternalEncoding,
+                                          LiteralConv.ExecEncoding);
+  if (ErrorOrConverter) {
+    LiteralConv.ToExecEncodingConverter =
+        new TextEncodingConverter(std::move(*ErrorOrConverter));
+  } else
+    return ErrorOrConverter.getError();
+  return std::error_code();
 }
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 55d9aced73ad0..b60369da069b3 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -147,7 +147,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
   // that would have been \", which would not have been the end of string.
   unsigned ResultChar = *ThisTokBuf++;
   char Escape = ResultChar;
-  bool Translate = true;
+  bool Transcode = true;
   bool Invalid = false;
   switch (ResultChar) {
   // These map to themselves.
@@ -189,7 +189,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
     ResultChar = 11;
     break;
   case 'x': { // Hex escape.
-    Translate = false;
+    Transcode = false;
     ResultChar = 0;
     if (ThisTokBuf != ThisTokEnd && *ThisTokBuf == '{') {
       Delimited = true;
@@ -253,7 +253,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
   case '4': case '5': case '6': case '7': {
     // Octal escapes.
     --ThisTokBuf;
-    Translate = false;
+    Transcode = false;
     ResultChar = 0;
 
     // Octal escapes are a series of octal digits with maximum length 3.
@@ -373,7 +373,7 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
     HadError = true;
   }
 
-  if (Translate && Converter) {
+  if (Transcode && Converter) {
     // Invalid escapes are written as '?' and then translated.
     char ByteChar = Invalid ? '?' : ResultChar;
     SmallString<8> ResultCharConv;
@@ -1834,8 +1834,8 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   }
 
   llvm::TextEncodingConverter *Converter = nullptr;
-  if (!isUTFLiteral(Kind) && LiteralConv)
-    Converter = LiteralConv->getConverter(ToExecEncoding);
+  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && LiteralConv)
+    Converter = LiteralConv->getConverter(CA_ToExecEncoding);
 
   while (begin != end) {
     // Is this a span of non-escape characters?
@@ -2142,7 +2142,7 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
   SourceLocation UDSuffixTokLoc;
 
   llvm::TextEncodingConverter *Converter = nullptr;
-  if (!isUTFLiteral(Kind) && LiteralConv)
+  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && LiteralConv)
     Converter = LiteralConv->getConverter(Action);
 
   for (unsigned i = 0, e = StringToks.size(); i != e; ++i) {
@@ -2264,9 +2264,18 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
           SmallString<256> CpConv;
           int ResultLength = BeforeCRLF.size() * CharByteWidth;
           char *Cp = ResultPtr - ResultLength;
-          Converter->convert(StringRef(Cp, ResultLength), CpConv);
-          memcpy(Cp, CpConv.data(), ResultLength);
-          ResultPtr = Cp + CpConv.size();
+          std::error_code EC =
+              Converter->convert(StringRef(Cp, ResultLength), CpConv);
+          if (EC) {
+            if (Diags)
+              Diags->Report(StringToks[i].getLocation(),
+                            diag::err_exec_charset_conversion_failed)
+                  << EC.message();
+            hadError = true;
+          } else {
+            memcpy(Cp, CpConv.data(), ResultLength);
+            ResultPtr = Cp + CpConv.size();
+          }
         }
         // Point into the \n inside the \r\n sequence and operate on the
         // remaining portion of the literal.
@@ -2314,9 +2323,18 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
             SmallString<256> CpConv;
             int ResultLength = Length * CharByteWidth;
             char *Cp = ResultPtr - ResultLength;
-            Converter->convert(StringRef(Cp, ResultLength), CpConv);
-            memcpy(Cp, CpConv.data(), ResultLength);
-            ResultPtr = Cp + CpConv.size();
+            std::error_code EC =
+                Converter->convert(StringRef(Cp, ResultLength), CpConv);
+            if (EC) {
+              if (Diags)
+                Diags->Report(StringToks[i].getLocation(),
+                              diag::err_exec_charset_conversion_failed)
+                    << EC.message();
+              hadError = true;
+            } else {
+              memcpy(Cp, CpConv.data(), ResultLength);
+              ResultPtr = Cp + CpConv.size();
+            }
           }
           continue;
         }
diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
index b0caab09405b3..caa370934065d 100644
--- a/clang/test/Driver/cl-options.c
+++ b/clang/test/Driver/cl-options.c
@@ -251,7 +251,7 @@
 // source-charset-utf-16: invalid value 'utf-16' in '/source-charset:utf-16'
 
 // /execution-charset: should warn on invalid charsets.
-// RUN: %clang_cl /execution-charset:invalid-charset -### -- %s 2>&1 | FileCheck -check-prefix=execution-charset-invalid %s
+// RUN: not %clang_cl /execution-charset:invalid-charset -### -- %s 2>&1 | FileCheck -check-prefix=execution-charset-invalid %s
 // execution-charset-invalid: invalid value 'invalid-charset' in '/execution-charset:invalid-charset'
 //
 
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index d791329b6c438..c9d5785783033 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -232,14 +232,16 @@
 // RUN: not %clang -### -S -finput-charset=iso-8859-1 -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-INPUT-CHARSET %s
 // CHECK-INVALID-INPUT-CHARSET: error: invalid value 'iso-8859-1' in '-finput-charset=iso-8859-1'
 
-// RUN: %clang -### -S -fexec-charset=invalid-charset -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-INPUT-CHARSET %s
-// CHECK-INVALID-INPUT-CHARSET: error: invalid value 'invalid-charset' in '-fexec-charset=invalid-charset'
-
-// Test that we support the following exec charsets.
-// RUN: %clang -### -S -fexec-charset=UTF-8 -o /dev/null %s 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: %clang -### -S -fexec-charset=ISO8859-1 -o /dev/null %s 2>&1 | FileCheck --check-prefix=INVALID %s
-// RUN: %clang -### -S -fexec-charset=IBM-1047 -o /dev/null %s 2>&1 | FileCheck --check-prefix=INVALID %s
-// INVALID-NOT: error: invalid value
+// RUN: not %clang -### -S -fexec-charset=invalid-charset -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-EXEC-CHARSET %s
+// CHECK-INVALID-EXEC-CHARSET: error: invalid value 'invalid-charset' in '-fexec-charset=invalid-charset'
+
+// Test that we support the following exec charsets. The preferred MIME name is
+// `IBM1047`, but `IBM-1047` is the name used by z/OS USS utilities such as
+// `chtag`.
+// RUN: %clang -### -S -fexec-charset=UTF-8 -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-EXEC-CHARSET-UTF-8 %s
+// RUN: %clang -### -S -fexec-charset=IBM-1047 -o /dev/null %s 2>&1 | FileCheck --check-prefix=CHECK-EXEC-CHARSET-IBM-1047 %s
+// CHECK-EXEC-CHARSET-UTF-8: "-fexec-charset" "UTF-8"
+// CHECK-EXEC-CHARSET-IBM-1047: "-fexec-charset" "IBM-1047"
 
 // Test that we don't error on these.
 // RUN: not %clang -### -S -Werror                                                \
diff --git a/llvm/include/llvm/Support/TextEncoding.h b/llvm/include/llvm/Support/TextEncoding.h
index 8a304910aa5dd..bda6f2a088eb2 100644
--- a/llvm/include/llvm/Support/TextEncoding.h
+++ b/llvm/include/llvm/Support/TextEncoding.h
@@ -135,6 +135,9 @@ class TextEncodingConverter {
       return std::string(Result);
     return EC;
   }
+
+  // Maps the encoding name to enum constant if possible.
+  static std::optional<TextEncoding> getKnownEncoding(StringRef Name);
 };
 
 } // namespace llvm
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index b88200eb0cf27..19586b7df9934 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -513,8 +513,8 @@ class Triple {
   /// For example, "fooos1.2.3" would return "1.2.3".
   LLVM_ABI StringRef getEnvironmentVersionString() const;
 
-  /// getDefaultTextEncoding - Get the default encoding of the triple.
-  StringRef getDefaultTextEncoding() const;
+  /// getDefaultNarrowTextEncoding - Get the default encoding of the triple.
+  StringRef getDefaultNarrowTextEncoding() const;
 
   /// @}
   /// @name Convenience Predicates
diff --git a/llvm/lib/Support/TextEncoding.cpp b/llvm/lib/Support/TextEncoding.cpp
index 453af6f7287bc..91bd482ea4a0c 100644
--- a/llvm/lib/Support/TextEncoding.cpp
+++ b/llvm/lib/Support/TextEncoding.cpp
@@ -44,7 +44,8 @@ static void normalizeCharSetName(StringRef CSName,
 }
 
 // Maps the encoding name to enum constant if possible.
-static std::optional<TextEncoding> getKnownEncoding(StringRef Name) {
+std::optional<TextEncoding>
+TextEncodingConverter::getKnownEncoding(StringRef Name) {
   SmallString<16> Normalized;
   normalizeCharSetName(Name, Normalized);
   if (Normalized.equals("utf8"))
diff --git a/llvm/lib/TargetParser/Triple.cpp b/llvm/lib/TargetParser/Triple.cpp
index b10421dc9dfae..9175a165e7691 100644
--- a/llvm/lib/TargetParser/Triple.cpp
+++ b/llvm/lib/TargetParser/Triple.cpp
@@ -1447,7 +1447,7 @@ StringRef Triple::getOSAndEnvironmentName() const {
 }
 
 // Default encoding on z/OS is IBM-1047 and UTF-8 otherwise
-StringRef Triple::getDefaultTextEncoding() const {
+StringRef Triple::getDefaultNarrowTextEncoding() const {
   if (getOS() == llvm::Triple::ZOS)
     return "IBM-1047";
   return "UTF-8";

>From 6930ac2086347aae08ee51d09e2078957f70abbf Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Mon, 10 Nov 2025 15:12:53 -0500
Subject: [PATCH 05/15] fix CI

---
 clang/lib/Frontend/CompilerInstance.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index c151d18e7e05e..85ac1bfd1303e 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -546,8 +546,8 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
   if (GetDependencyDirectives)
     PP->setDependencyDirectivesGetter(*GetDependencyDirectives);
 
-  if (!LiteralConverter::setConvertersFromOptions(PP->getLiteralConverter(),
-                                                  getLangOpts(), getTarget()))
+  if (LiteralConverter::setConvertersFromOptions(PP->getLiteralConverter(),
+                                                 getLangOpts(), getTarget()))
     PP->getDiagnostics().Report(clang::diag::err_fe_literal_conv_config);
 }
 

>From 45422864b078f3f4fd49ed4619e7e382dc299da4 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Wed, 12 Nov 2025 11:51:52 -0500
Subject: [PATCH 06/15] add more error handling, address comments

---
 clang/lib/Lex/LiteralSupport.cpp | 110 +++++++++++++++++++------------
 1 file changed, 68 insertions(+), 42 deletions(-)

diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index b60369da069b3..f652a41300a43 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1766,7 +1766,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   HadError = false;
 
   Kind = kind;
-  LiteralConverter *LiteralConv = &PP.getLiteralConverter();
+  LiteralConverter LiteralConv = PP.getLiteralConverter();
 
   const char *TokBegin = begin;
 
@@ -1834,8 +1834,8 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   }
 
   llvm::TextEncodingConverter *Converter = nullptr;
-  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && LiteralConv)
-    Converter = LiteralConv->getConverter(CA_ToExecEncoding);
+  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind))
+    Converter = LiteralConv.getConverter(CA_ToExecEncoding);
 
   while (begin != end) {
     // Is this a span of non-escape characters?
@@ -1902,21 +1902,29 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
           PP.Diag(Loc, diag::err_character_too_large);
         }
       } else {
-        char Cp[8];
+        char Cp[5];
         char *ResultPtr = Cp;
-        unsigned CharByteWidth = 1;
         EncodeUCNEscape(TokBegin, begin, end, ResultPtr, HadError,
                         FullSourceLoc(Loc, PP.getSourceManager()),
-                        CharByteWidth, &PP.getDiagnostics(), PP.getLangOpts());
+                        /*CharByteWidth=*/1u, &PP.getDiagnostics(),
+                        PP.getLangOpts());
+        assert(ResultPtr - Cp <= 4 &&
+               "unexpected result size for UCN escape character");
         if (!HadError) {
           SmallString<8> CpConv;
-          Converter->convert(StringRef(Cp), CpConv);
-          if (CpConv.size() > 1) {
+          StringRef ToConvert(Cp, ResultPtr - Cp);
+          std::error_code EC = Converter->convert(StringRef(Cp), CpConv);
+          if (EC) {
+            PP.Diag(Loc, diag::err_exec_charset_conversion_failed)
+                << EC.message();
             HadError = true;
-            PP.Diag(Loc, diag::err_character_too_large);
           } else {
-            memcpy(Cp, CpConv.data(), CpConv.size());
-            *buffer_begin = *Cp;
+            if (CpConv.size() > 1) {
+              HadError = true;
+              PP.Diag(Loc, diag::err_character_too_large);
+            } else {
+              *buffer_begin = CpConv[0];
+            }
           }
         }
       }
@@ -2048,6 +2056,42 @@ StringLiteralParser::StringLiteralParser(ArrayRef<Token> StringToks,
   init(StringToks, Action);
 }
 
+static char *convertCharactersInPlace(char *ResultPtr, char *ResultPtrBefore,
+                                      const unsigned CharByteWidth,
+                                      bool &hadError,
+                                      llvm::TextEncodingConverter &Converter) {
+  assert(!hadError && "Unexpected call to convertCharactersInPlace");
+
+  SmallString<256> CpConv;
+  int ResultLength = ResultPtr - ResultPtrBefore;
+  assert(ResultLength % CharByteWidth == 0 &&
+         "Unexpected span of bytes for the characters.");
+  char *Cp = ResultPtrBefore;
+  if (Converter.convert(StringRef(Cp, ResultLength / CharByteWidth), CpConv)) {
+    hadError = true;
+    return ResultPtr;
+  }
+  if (CharByteWidth == 1) {
+    memcpy(Cp, CpConv.data(), CpConv.size());
+    return Cp + CpConv.size();
+  }
+  std::string UTF8String;
+  if (CharByteWidth == 4)
+    convertUTF32ToUTF8String(ArrayRef<char>(Cp, ResultLength), UTF8String);
+  else if (CharByteWidth == 2)
+    convertUTF16ToUTF8String(ArrayRef<char>(Cp, ResultLength), UTF8String);
+  if (Converter.convert(UTF8String, CpConv)) {
+    hadError = true;
+    return ResultPtr;
+  }
+  int NewCharByteWidth = ((int)CpConv.size()) / (ResultLength / CharByteWidth);
+  unsigned EndianOffset = llvm::sys::IsBigEndianHost ? CharByteWidth - 1 : 0;
+  for (int i = 0; i < (int)CpConv.size(); i += NewCharByteWidth)
+    memcpy(Cp + EndianOffset + i * CharByteWidth, CpConv.data() + i,
+           NewCharByteWidth);
+  return Cp + CpConv.size() * CharByteWidth;
+}
+
 void StringLiteralParser::init(ArrayRef<Token> StringToks,
                                ConversionAction Action) {
   // The literal token may have come from an invalid source location (e.g. due
@@ -2254,6 +2298,7 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
         StringRef BeforeCRLF = RemainingTokenSpan.substr(0, CRLFPos);
         StringRef AfterCRLF = RemainingTokenSpan.substr(CRLFPos);
 
+        char *ResultPtrBefore = ResultPtr;
         // Copy everything before the \r\n sequence into the string literal.
         if (CopyStringFragment(StringToks[i], ThisTokBegin, BeforeCRLF))
           hadError = true;
@@ -2261,21 +2306,11 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
         if (!hadError && Converter) {
           assert(Kind != tok::wide_string_literal &&
                  "Wide character translation not supported");
-          SmallString<256> CpConv;
-          int ResultLength = BeforeCRLF.size() * CharByteWidth;
-          char *Cp = ResultPtr - ResultLength;
-          std::error_code EC =
-              Converter->convert(StringRef(Cp, ResultLength), CpConv);
-          if (EC) {
-            if (Diags)
-              Diags->Report(StringToks[i].getLocation(),
-                            diag::err_exec_charset_conversion_failed)
-                  << EC.message();
-            hadError = true;
-          } else {
-            memcpy(Cp, CpConv.data(), ResultLength);
-            ResultPtr = Cp + CpConv.size();
-          }
+          ResultPtr = convertCharactersInPlace(
+              ResultPtr, ResultPtrBefore, CharByteWidth, hadError, *Converter);
+          if (hadError && Diags)
+            Diags->Report(StringToks[i].getLocation(),
+                          diag::err_exec_charset_conversion_failed);
         }
         // Point into the \n inside the \r\n sequence and operate on the
         // remaining portion of the literal.
@@ -2311,7 +2346,7 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
             ++ThisTokBuf;
           } while (ThisTokBuf != ThisTokEnd && ThisTokBuf[0] != '\\');
 
-          int Length = ThisTokBuf - InStart;
+          char *ResultPtrBefore = ResultPtr;
           // Copy the character span over.
           if (CopyStringFragment(StringToks[i], ThisTokBegin,
                                  StringRef(InStart, ThisTokBuf - InStart)))
@@ -2320,21 +2355,12 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
           if (!hadError && Converter) {
             assert(Kind != tok::wide_string_literal &&
                    "Wide character translation not supported");
-            SmallString<256> CpConv;
-            int ResultLength = Length * CharByteWidth;
-            char *Cp = ResultPtr - ResultLength;
-            std::error_code EC =
-                Converter->convert(StringRef(Cp, ResultLength), CpConv);
-            if (EC) {
-              if (Diags)
-                Diags->Report(StringToks[i].getLocation(),
-                              diag::err_exec_charset_conversion_failed)
-                    << EC.message();
-              hadError = true;
-            } else {
-              memcpy(Cp, CpConv.data(), ResultLength);
-              ResultPtr = Cp + CpConv.size();
-            }
+            ResultPtr =
+                convertCharactersInPlace(ResultPtr, ResultPtrBefore,
+                                         CharByteWidth, hadError, *Converter);
+            if (hadError && Diags)
+              Diags->Report(StringToks[i].getLocation(),
+                            diag::err_exec_charset_conversion_failed);
           }
           continue;
         }

>From 123048c74b572233e2e9c8f8d47b11a83c3c8566 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Mon, 15 Dec 2025 11:39:03 -0500
Subject: [PATCH 07/15] add proper diagnostics for char conversion

---
 .../include/clang/Basic/DiagnosticLexKinds.td |  2 ++
 clang/lib/Lex/LiteralSupport.cpp              | 34 ++++++++++++++-----
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticLexKinds.td b/clang/include/clang/Basic/DiagnosticLexKinds.td
index 2d239a7880ac8..1af3e5d20f99a 100644
--- a/clang/include/clang/Basic/DiagnosticLexKinds.td
+++ b/clang/include/clang/Basic/DiagnosticLexKinds.td
@@ -289,6 +289,8 @@ def err_character_too_large : Error<
   "character too large for enclosing character literal type">;
 def err_exec_charset_conversion_failed : Error<
   "conversion to execution encoding failed: '%0'">;
+def err_char_size_increased_after_conversion
+    : Error<"character size of '%0' increased after conversion">;
 def warn_c99_compat_unicode_literal : Warning<
   "unicode literals are incompatible with C99">,
   InGroup<C99Compat>, DefaultIgnore;
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index f652a41300a43..73e119139a80b 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -377,10 +377,20 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
     // Invalid escapes are written as '?' and then translated.
     char ByteChar = Invalid ? '?' : ResultChar;
     SmallString<8> ResultCharConv;
-    Converter->convert(StringRef(&ByteChar, 1), ResultCharConv);
-    assert(ResultCharConv.size() == 1 &&
-           "Char size increased after translation");
-    ResultChar = ResultCharConv[0];
+    std::error_code EC =
+        Converter->convert(StringRef(&ByteChar, 1), ResultCharConv);
+    if (EC) {
+      Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
+           diag::err_exec_charset_conversion_failed)
+          << EC.message();
+      HadError = true;
+    } else {
+      if (ResultCharConv.size() > 1)
+        Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
+             diag::err_char_size_increased_after_conversion)
+            << ByteChar;
+      ResultChar = ResultCharConv[0];
+    }
   }
   return ResultChar;
 }
@@ -1879,10 +1889,18 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
                    "Wide character translation not supported");
             char ByteChar = *tmp_out_start;
             SmallString<1> ConvertedChar;
-            Converter->convert(StringRef(&ByteChar, 1), ConvertedChar);
-            assert(ConvertedChar.size() == 1 &&
-                   "Char size increased after translation");
-            *tmp_out_start = ConvertedChar[0];
+            std::error_code EC =
+                Converter->convert(StringRef(&ByteChar, 1), ConvertedChar);
+            if (EC) {
+              PP.Diag(Loc, diag::err_exec_charset_conversion_failed)
+                  << EC.message();
+              HadError = true;
+            } else {
+              if (ConvertedChar.size() > 1)
+                PP.Diag(Loc, diag::err_char_size_increased_after_conversion)
+                    << ByteChar;
+              *tmp_out_start = ConvertedChar[0];
+            }
           }
         }
       }

>From b3bc569c8dace6105d2f8e8bb84c978f141a9478 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Tue, 16 Dec 2025 09:02:22 -0500
Subject: [PATCH 08/15] rename LiteralConverter to TextEncodingConfig

---
 clang/include/clang/Lex/LiteralSupport.h      | 10 ++---
 clang/include/clang/Lex/Preprocessor.h        |  6 +--
 ...iteralConverter.h => TextEncodingConfig.h} |  6 +--
 clang/lib/Frontend/CompilerInstance.cpp       |  6 +--
 clang/lib/Lex/CMakeLists.txt                  |  2 +-
 clang/lib/Lex/LiteralSupport.cpp              | 10 ++---
 ...alConverter.cpp => TextEncodingConfig.cpp} | 37 +++++++++----------
 7 files changed, 38 insertions(+), 39 deletions(-)
 rename clang/include/clang/Lex/{LiteralConverter.h => TextEncodingConfig.h} (88%)
 rename clang/lib/Lex/{LiteralConverter.cpp => TextEncodingConfig.cpp} (50%)

diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
index 32ae829096592..b4defac24bf7c 100644
--- a/clang/include/clang/Lex/LiteralSupport.h
+++ b/clang/include/clang/Lex/LiteralSupport.h
@@ -17,7 +17,7 @@
 #include "clang/Basic/CharInfo.h"
 #include "clang/Basic/LLVM.h"
 #include "clang/Basic/TokenKinds.h"
-#include "clang/Lex/LiteralConverter.h"
+#include "clang/Lex/TextEncodingConfig.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallString.h"
@@ -234,7 +234,7 @@ class StringLiteralParser {
   const LangOptions &Features;
   const TargetInfo &Target;
   DiagnosticsEngine *Diags;
-  LiteralConverter *LiteralConv;
+  TextEncodingConfig *TEC;
 
   unsigned MaxTokenLength;
   unsigned SizeBound;
@@ -255,9 +255,9 @@ class StringLiteralParser {
   StringLiteralParser(ArrayRef<Token> StringToks, const SourceManager &sm,
                       const LangOptions &features, const TargetInfo &target,
                       DiagnosticsEngine *diags = nullptr)
-      : SM(sm), Features(features), Target(target), Diags(diags),
-        LiteralConv(nullptr), MaxTokenLength(0), SizeBound(0), CharByteWidth(0),
-        Kind(tok::unknown), ResultPtr(ResultBuf.data()),
+      : SM(sm), Features(features), Target(target), Diags(diags), TEC(nullptr),
+        MaxTokenLength(0), SizeBound(0), CharByteWidth(0), Kind(tok::unknown),
+        ResultPtr(ResultBuf.data()),
         EvalMethod(StringLiteralEvalMethod::Evaluated), hadError(false),
         Pascal(false) {
     init(StringToks, CA_NoConversion);
diff --git a/clang/include/clang/Lex/Preprocessor.h b/clang/include/clang/Lex/Preprocessor.h
index 62a65d4127947..b5c6970e4f64f 100644
--- a/clang/include/clang/Lex/Preprocessor.h
+++ b/clang/include/clang/Lex/Preprocessor.h
@@ -25,12 +25,12 @@
 #include "clang/Basic/TokenKinds.h"
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/Lexer.h"
-#include "clang/Lex/LiteralConverter.h"
 #include "clang/Lex/MacroInfo.h"
 #include "clang/Lex/ModuleLoader.h"
 #include "clang/Lex/ModuleMap.h"
 #include "clang/Lex/PPCallbacks.h"
 #include "clang/Lex/PPEmbedParameters.h"
+#include "clang/Lex/TextEncodingConfig.h"
 #include "clang/Lex/Token.h"
 #include "clang/Lex/TokenLexer.h"
 #include "clang/Support/Compiler.h"
@@ -223,7 +223,7 @@ class Preprocessor {
   std::unique_ptr<ScratchBuffer> ScratchBuf;
   HeaderSearch      &HeaderInfo;
   ModuleLoader      &TheModuleLoader;
-  LiteralConverter LiteralConv;
+  TextEncodingConfig TEC;
 
   /// External source of macros.
   ExternalPreprocessorSource *ExternalSource;
@@ -1301,7 +1301,7 @@ class Preprocessor {
   SelectorTable &getSelectorTable() { return Selectors; }
   Builtin::Context &getBuiltinInfo() { return *BuiltinInfo; }
   llvm::BumpPtrAllocator &getPreprocessorAllocator() { return BP; }
-  LiteralConverter &getLiteralConverter() { return LiteralConv; }
+  TextEncodingConfig &getTextEncodingConfig() { return TEC; }
 
   void setExternalSource(ExternalPreprocessorSource *Source) {
     ExternalSource = Source;
diff --git a/clang/include/clang/Lex/LiteralConverter.h b/clang/include/clang/Lex/TextEncodingConfig.h
similarity index 88%
rename from clang/include/clang/Lex/LiteralConverter.h
rename to clang/include/clang/Lex/TextEncodingConfig.h
index 6a66d2d0ff707..43933801ca00d 100644
--- a/clang/include/clang/Lex/LiteralConverter.h
+++ b/clang/include/clang/Lex/TextEncodingConfig.h
@@ -1,4 +1,4 @@
-//===--- clang/Lex/LiteralConverter.h - Translator for Literals -*- C++ -*-===//
+//===-- clang/Lex/TextEncodingConfig.h - Text Conversion Config -*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -22,7 +22,7 @@ enum ConversionAction {
   CA_ToExecEncoding
 };
 
-class LiteralConverter {
+class TextEncodingConfig {
   llvm::StringRef InternalEncoding;
   llvm::StringRef SystemEncoding;
   llvm::StringRef ExecEncoding;
@@ -32,7 +32,7 @@ class LiteralConverter {
 public:
   llvm::TextEncodingConverter *getConverter(ConversionAction Action);
   static std::error_code
-  setConvertersFromOptions(LiteralConverter &LiteralConv,
+  setConvertersFromOptions(TextEncodingConfig &TEC,
                            const clang::LangOptions &Opts,
                            const clang::TargetInfo &TInfo);
 };
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 85ac1bfd1303e..6a35e1c1b234b 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -32,9 +32,9 @@
 #include "clang/Frontend/Utils.h"
 #include "clang/Frontend/VerifyDiagnosticConsumer.h"
 #include "clang/Lex/HeaderSearch.h"
-#include "clang/Lex/LiteralConverter.h"
 #include "clang/Lex/Preprocessor.h"
 #include "clang/Lex/PreprocessorOptions.h"
+#include "clang/Lex/TextEncodingConfig.h"
 #include "clang/Sema/CodeCompleteConsumer.h"
 #include "clang/Sema/ParsedAttr.h"
 #include "clang/Sema/Sema.h"
@@ -546,8 +546,8 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
   if (GetDependencyDirectives)
     PP->setDependencyDirectivesGetter(*GetDependencyDirectives);
 
-  if (LiteralConverter::setConvertersFromOptions(PP->getLiteralConverter(),
-                                                 getLangOpts(), getTarget()))
+  if (TextEncodingConfig::setConvertersFromOptions(PP->getTextEncodingConfig(),
+                                                   getLangOpts(), getTarget()))
     PP->getDiagnostics().Report(clang::diag::err_fe_literal_conv_config);
 }
 
diff --git a/clang/lib/Lex/CMakeLists.txt b/clang/lib/Lex/CMakeLists.txt
index 9e38a1b8fbb44..106a5d3b126be 100644
--- a/clang/lib/Lex/CMakeLists.txt
+++ b/clang/lib/Lex/CMakeLists.txt
@@ -12,7 +12,6 @@ add_clang_library(clangLex
   InitHeaderSearch.cpp
   Lexer.cpp
   LexHLSLRootSignature.cpp
-  LiteralConverter.cpp
   LiteralSupport.cpp
   MacroArgs.cpp
   MacroInfo.cpp
@@ -30,6 +29,7 @@ add_clang_library(clangLex
   Preprocessor.cpp
   PreprocessorLexer.cpp
   ScratchBuffer.cpp
+  TextEncodingConfig.cpp
   TokenConcatenation.cpp
   TokenLexer.cpp
 
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index 73e119139a80b..e57b5a8b48c43 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1776,7 +1776,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   HadError = false;
 
   Kind = kind;
-  LiteralConverter LiteralConv = PP.getLiteralConverter();
+  TextEncodingConfig TEC = PP.getTextEncodingConfig();
 
   const char *TokBegin = begin;
 
@@ -1845,7 +1845,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
 
   llvm::TextEncodingConverter *Converter = nullptr;
   if (!isUTFLiteral(Kind) && !isWideLiteral(Kind))
-    Converter = LiteralConv.getConverter(CA_ToExecEncoding);
+    Converter = TEC.getConverter(CA_ToExecEncoding);
 
   while (begin != end) {
     // Is this a span of non-escape characters?
@@ -2068,7 +2068,7 @@ StringLiteralParser::StringLiteralParser(ArrayRef<Token> StringToks,
                                          ConversionAction Action)
     : SM(PP.getSourceManager()), Features(PP.getLangOpts()),
       Target(PP.getTargetInfo()), Diags(&PP.getDiagnostics()),
-      LiteralConv(&PP.getLiteralConverter()), MaxTokenLength(0), SizeBound(0),
+      TEC(&PP.getTextEncodingConfig()), MaxTokenLength(0), SizeBound(0),
       CharByteWidth(0), Kind(tok::unknown), ResultPtr(ResultBuf.data()),
       EvalMethod(EvalMethod), hadError(false), Pascal(false) {
   init(StringToks, Action);
@@ -2204,8 +2204,8 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
   SourceLocation UDSuffixTokLoc;
 
   llvm::TextEncodingConverter *Converter = nullptr;
-  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && LiteralConv)
-    Converter = LiteralConv->getConverter(Action);
+  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && TEC)
+    Converter = TEC->getConverter(Action);
 
   for (unsigned i = 0, e = StringToks.size(); i != e; ++i) {
     const char *ThisTokBuf = &TokenBuf[0];
diff --git a/clang/lib/Lex/LiteralConverter.cpp b/clang/lib/Lex/TextEncodingConfig.cpp
similarity index 50%
rename from clang/lib/Lex/LiteralConverter.cpp
rename to clang/lib/Lex/TextEncodingConfig.cpp
index 2bd177d499b87..7fcaabdeb4b88 100644
--- a/clang/lib/Lex/LiteralConverter.cpp
+++ b/clang/lib/Lex/TextEncodingConfig.cpp
@@ -1,4 +1,4 @@
-//===--- LiteralConverter.cpp - Translator for String Literals -----------===//
+//===--- TextEncodingConfig.cpp -------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -6,13 +6,13 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "clang/Lex/LiteralConverter.h"
+#include "clang/Lex/TextEncodingConfig.h"
 #include "clang/Basic/DiagnosticDriver.h"
 
 using namespace llvm;
 
 llvm::TextEncodingConverter *
-LiteralConverter::getConverter(ConversionAction Action) {
+TextEncodingConfig::getConverter(ConversionAction Action) {
   if (Action == CA_ToSystemEncoding)
     return ToSystemEncodingConverter;
   else if (Action == CA_ToExecEncoding)
@@ -22,23 +22,22 @@ LiteralConverter::getConverter(ConversionAction Action) {
 }
 
 std::error_code
-LiteralConverter::setConvertersFromOptions(LiteralConverter &LiteralConv,
-                                           const clang::LangOptions &Opts,
-                                           const clang::TargetInfo &TInfo) {
+TextEncodingConfig::setConvertersFromOptions(TextEncodingConfig &TEC,
+                                             const clang::LangOptions &Opts,
+                                             const clang::TargetInfo &TInfo) {
   using namespace llvm;
-  LiteralConv.InternalEncoding = "UTF-8";
-  LiteralConv.SystemEncoding = TInfo.getTriple().getDefaultNarrowTextEncoding();
-  LiteralConv.ExecEncoding = Opts.ExecEncoding.empty()
-                                 ? LiteralConv.InternalEncoding
-                                 : Opts.ExecEncoding;
+  TEC.InternalEncoding = "UTF-8";
+  TEC.SystemEncoding = TInfo.getTriple().getDefaultNarrowTextEncoding();
+  TEC.ExecEncoding =
+      Opts.ExecEncoding.empty() ? TEC.InternalEncoding : Opts.ExecEncoding;
 
   // Create converter between internal and system encoding
-  if (LiteralConv.InternalEncoding != LiteralConv.SystemEncoding) {
+  if (TEC.InternalEncoding != TEC.SystemEncoding) {
     ErrorOr<TextEncodingConverter> ErrorOrConverter =
-        llvm::TextEncodingConverter::create(LiteralConv.InternalEncoding,
-                                            LiteralConv.SystemEncoding);
+        llvm::TextEncodingConverter::create(TEC.InternalEncoding,
+                                            TEC.SystemEncoding);
     if (ErrorOrConverter) {
-      LiteralConv.ToSystemEncodingConverter =
+      TEC.ToSystemEncodingConverter =
           new TextEncodingConverter(std::move(*ErrorOrConverter));
     } else
       return ErrorOrConverter.getError();
@@ -46,13 +45,13 @@ LiteralConverter::setConvertersFromOptions(LiteralConverter &LiteralConv,
 
   // Create converter between internal and exec encoding specified
   // in fexec-charset option.
-  if (LiteralConv.InternalEncoding == LiteralConv.ExecEncoding)
+  if (TEC.InternalEncoding == TEC.ExecEncoding)
     return std::error_code();
   ErrorOr<TextEncodingConverter> ErrorOrConverter =
-      llvm::TextEncodingConverter::create(LiteralConv.InternalEncoding,
-                                          LiteralConv.ExecEncoding);
+      llvm::TextEncodingConverter::create(TEC.InternalEncoding,
+                                          TEC.ExecEncoding);
   if (ErrorOrConverter) {
-    LiteralConv.ToExecEncodingConverter =
+    TEC.ToExecEncodingConverter =
         new TextEncodingConverter(std::move(*ErrorOrConverter));
   } else
     return ErrorOrConverter.getError();

>From f3448bfc65c6e70a4b6f0f655158e4132ac33ca0 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Tue, 16 Dec 2025 15:09:39 -0500
Subject: [PATCH 09/15] improve testcase

---
 .../clang/Basic/DiagnosticFrontendKinds.td     |  4 ++--
 clang/lib/Frontend/CompilerInstance.cpp        |  2 +-
 clang/test/CodeGen/systemz-charset.c           | 18 +++++++++++++++---
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 78677396eeab1..33bc20bfb4cc0 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -338,8 +338,8 @@ def err_non_default_visibility_dllimport : Error<
   "non-default visibility cannot be applied to 'dllimport' declaration">;
 def err_ifunc_resolver_return : Error<
   "ifunc resolver function must return a pointer">;
-def err_fe_literal_conv_config : Error<
-  "failed to configure the literal converter">;
+def err_fe_text_encoding_config
+    : Error<"failed to configure the text encoding config">;
 def warn_atomic_op_misaligned : Warning<
   "misaligned atomic operation may incur "
   "significant performance penalty"
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 6a35e1c1b234b..9d523d096f47d 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -548,7 +548,7 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
 
   if (TextEncodingConfig::setConvertersFromOptions(PP->getTextEncodingConfig(),
                                                    getLangOpts(), getTarget()))
-    PP->getDiagnostics().Report(clang::diag::err_fe_literal_conv_config);
+    PP->getDiagnostics().Report(clang::diag::err_fe_text_encoding_config);
 }
 
 std::string
diff --git a/clang/test/CodeGen/systemz-charset.c b/clang/test/CodeGen/systemz-charset.c
index aab43157b1be4..c68c58219c2af 100644
--- a/clang/test/CodeGen/systemz-charset.c
+++ b/clang/test/CodeGen/systemz-charset.c
@@ -1,35 +1,47 @@
 // RUN: %clang_cc1 %s -emit-llvm -triple s390x-none-zos -fexec-charset IBM-1047 -o - | FileCheck %s
 // RUN: %clang %s -emit-llvm -S -target s390x-ibm-zos -o - | FileCheck %s
+// RUN: %clang_cc1 %s -emit-llvm -triple s390x-none-zos -fexec-charset UTF-8 -o - | FileCheck %s --check-prefix=CHECK-UTF8
 
 const char *UpperCaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
-// CHECK: c"\C1\C2\C3\C4\C5\C6\C7\C8\C9\D1\D2\D3\D4\D5\D6\D7\D8\D9\E2\E3\E4\E5\E6\E7\E8\E9\00"
+//CHECK: c"\C1\C2\C3\C4\C5\C6\C7\C8\C9\D1\D2\D3\D4\D5\D6\D7\D8\D9\E2\E3\E4\E5\E6\E7\E8\E9\00"
+//CHECK-UTF8: c"ABCDEFGHIJKLMNOPQRSTUVWXYZ\00"
 
 const char *LowerCaseLetters = "abcdefghijklmnopqrstuvwxyz";
 //CHECK: c"\81\82\83\84\85\86\87\88\89\91\92\93\94\95\96\97\98\99\A2\A3\A4\A5\A6\A7\A8\A9\00"
+//CHECK-UTF8: c"abcdefghijklmnopqrstuvwxyz\00"
 
 const char *Digits = "0123456789";
-// CHECK: c"\F0\F1\F2\F3\F4\F5\F6\F7\F8\F9\00"
+//CHECK: c"\F0\F1\F2\F3\F4\F5\F6\F7\F8\F9\00"
+//CHECK-UTF8: c"0123456789\00"
 
 const char *SpecialCharacters = " .<(+|&!$*);^-/,%%_>`:#@=";
-// CHECK: c"@KLMNOPZ[\\]^_`akllmnyz{|~\00"
+//CHECK: c"@KLMNOPZ[\\]^_`akllmnyz{|~\00"
+//CHECK-UTF8: c" .<(+|&!$*);^-/,%%_>`:#@=\00"
 
 const char *EscapeCharacters = "\a\b\f\n\r\t\v\\\'\"\?";
 //CHECK: c"/\16\0C\15\0D\05\0B\E0}\7Fo\00"
+//CHECK-UTF8: c"\07\08\0C\0A\0D\09\0B\\'\22?\00"
 
 const char *InvalidEscape = "\y\z";
 //CHECK: c"oo\00"
+//CHECK-UTF8: c"yz\00"
 
 const char *HexCharacters = "\x12\x13\x14";
 //CHECK: c"\12\13\14\00"
+//CHECK-UTF8: c"\12\13\14\00"
 
 const char *OctalCharacters = "\141\142\143";
 //CHECK: c"abc\00"
+//CHECK-UTF8: c"abc\00"
 
 const char singleChar = 'a';
 //CHECK: i8 -127
+//CHECK-UTF8: 97
 
 const char *UcnCharacters = "\u00E2\u00AC\U000000DF";
 //CHECK: c"B\B0Y\00"
+//CHECK-UTF8: c"\C3\A2\C2\AC\C3\9F\00"
 
 const char *Unicode = "ÿ";
 //CHECK: c"\DF\00"
+//CHECK-UTF8: c"\C3\BF\00"

>From 96bf61e3e27af1caeca58208855a63a7ac1556db Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Mon, 12 Jan 2026 14:24:09 -0500
Subject: [PATCH 10/15] address comments

---
 clang/include/clang/Lex/LiteralSupport.h     |  1 +
 clang/include/clang/Lex/TextEncodingConfig.h |  6 +++---
 clang/lib/Driver/ToolChains/Clang.cpp        | 12 ++++++------
 clang/lib/Lex/LiteralSupport.cpp             |  6 +++---
 clang/lib/Lex/TextEncodingConfig.cpp         | 10 ++++++----
 llvm/include/llvm/TargetParser/Triple.h      |  3 ++-
 6 files changed, 21 insertions(+), 17 deletions(-)

diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
index b4defac24bf7c..4af60814668e6 100644
--- a/clang/include/clang/Lex/LiteralSupport.h
+++ b/clang/include/clang/Lex/LiteralSupport.h
@@ -24,6 +24,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/TextEncoding.h"
+
 namespace clang {
 
 class DiagnosticsEngine;
diff --git a/clang/include/clang/Lex/TextEncodingConfig.h b/clang/include/clang/Lex/TextEncodingConfig.h
index 43933801ca00d..492551571ae70 100644
--- a/clang/include/clang/Lex/TextEncodingConfig.h
+++ b/clang/include/clang/Lex/TextEncodingConfig.h
@@ -6,8 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-#ifndef LLVM_CLANG_LEX_LITERALCONVERTER_H
-#define LLVM_CLANG_LEX_LITERALCONVERTER_H
+#ifndef LLVM_CLANG_LEX_TEXTENCODINGCONFIG_H
+#define LLVM_CLANG_LEX_TEXTENCODINGCONFIG_H
 
 #include "clang/Basic/Diagnostic.h"
 #include "clang/Basic/LangOptions.h"
@@ -30,7 +30,7 @@ class TextEncodingConfig {
   llvm::TextEncodingConverter *ToExecEncodingConverter = nullptr;
 
 public:
-  llvm::TextEncodingConverter *getConverter(ConversionAction Action);
+  llvm::TextEncodingConverter *getConverter(ConversionAction Action) const;
   static std::error_code
   setConvertersFromOptions(TextEncodingConfig &TEC,
                            const clang::LangOptions &Opts,
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 631fe204cdd22..e0b863d0598cc 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7565,19 +7565,19 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
                                           << value;
   }
 
-  if (Arg *execEncoding = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
-    StringRef value = execEncoding->getValue();
+  if (Arg *ExecEncoding = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
+    StringRef Value = ExecEncoding->getValue();
     bool KnownEncoding =
-        llvm::TextEncodingConverter::getKnownEncoding(value).has_value();
+        llvm::TextEncodingConverter::getKnownEncoding(Value).has_value();
     if (!KnownEncoding) {
       llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
-          llvm::TextEncodingConverter::create("UTF-8", value.data());
+          llvm::TextEncodingConverter::create("UTF-8", Value.data());
       if (!ErrorOrConverter)
         D.Diag(diag::err_drv_invalid_value)
-            << execEncoding->getAsString(Args) << value;
+            << ExecEncoding->getAsString(Args) << Value;
     }
     CmdArgs.push_back("-fexec-charset");
-    CmdArgs.push_back(Args.MakeArgString(value));
+    CmdArgs.push_back(Args.MakeArgString(Value));
   } else {
     // Set the default fexec-charset as the system charset.
     CmdArgs.push_back("-fexec-charset");
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index e57b5a8b48c43..ce5030240e133 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1776,7 +1776,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   HadError = false;
 
   Kind = kind;
-  TextEncodingConfig TEC = PP.getTextEncodingConfig();
+  const TextEncodingConfig TEC = PP.getTextEncodingConfig();
 
   const char *TokBegin = begin;
 
@@ -1844,7 +1844,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   }
 
   llvm::TextEncodingConverter *Converter = nullptr;
-  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind))
+  if (isOrdinary())
     Converter = TEC.getConverter(CA_ToExecEncoding);
 
   while (begin != end) {
@@ -2204,7 +2204,7 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
   SourceLocation UDSuffixTokLoc;
 
   llvm::TextEncodingConverter *Converter = nullptr;
-  if (!isUTFLiteral(Kind) && !isWideLiteral(Kind) && TEC)
+  if (isOrdinary() && TEC)
     Converter = TEC->getConverter(Action);
 
   for (unsigned i = 0, e = StringToks.size(); i != e; ++i) {
diff --git a/clang/lib/Lex/TextEncodingConfig.cpp b/clang/lib/Lex/TextEncodingConfig.cpp
index 7fcaabdeb4b88..b8e5109241128 100644
--- a/clang/lib/Lex/TextEncodingConfig.cpp
+++ b/clang/lib/Lex/TextEncodingConfig.cpp
@@ -12,13 +12,15 @@
 using namespace llvm;
 
 llvm::TextEncodingConverter *
-TextEncodingConfig::getConverter(ConversionAction Action) {
-  if (Action == CA_ToSystemEncoding)
+TextEncodingConfig::getConverter(ConversionAction Action) const {
+  switch (Action) {
+  case CA_ToSystemEncoding:
     return ToSystemEncodingConverter;
-  else if (Action == CA_ToExecEncoding)
+  case CA_ToExecEncoding:
     return ToExecEncodingConverter;
-  else
+  default:
     return nullptr;
+  }
 }
 
 std::error_code
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index 19586b7df9934..192647977db76 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -513,7 +513,8 @@ class Triple {
   /// For example, "fooos1.2.3" would return "1.2.3".
   LLVM_ABI StringRef getEnvironmentVersionString() const;
 
-  /// getDefaultNarrowTextEncoding - Get the default encoding of the triple.
+  /// Get the default system encoding of the triple.
+  /// For example, "IBM-1047" for z/OS, "UTF-8" for others
   StringRef getDefaultNarrowTextEncoding() const;
 
   /// @}

>From 4ca764cf7ebb174151cdc71768af122c0aca930b Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Tue, 13 Jan 2026 09:13:42 -0500
Subject: [PATCH 11/15] remove implementation details from driver, use const
 reference

---
 clang/lib/Driver/ToolChains/Clang.cpp    | 16 ++++++----------
 clang/lib/Lex/LiteralSupport.cpp         |  2 +-
 llvm/include/llvm/Support/TextEncoding.h |  3 +--
 llvm/include/llvm/TargetParser/Triple.h  |  2 +-
 llvm/lib/Support/TextEncoding.cpp        | 13 +++++++++++--
 5 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index e0b863d0598cc..e2de73313f42e 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7567,17 +7567,13 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
 
   if (Arg *ExecEncoding = Args.getLastArg(options::OPT_fexec_charset_EQ)) {
     StringRef Value = ExecEncoding->getValue();
-    bool KnownEncoding =
-        llvm::TextEncodingConverter::getKnownEncoding(Value).has_value();
-    if (!KnownEncoding) {
-      llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
-          llvm::TextEncodingConverter::create("UTF-8", Value.data());
-      if (!ErrorOrConverter)
-        D.Diag(diag::err_drv_invalid_value)
-            << ExecEncoding->getAsString(Args) << Value;
+    if (llvm::TextEncodingConverter::isEncodingSupported(Value)) {
+      CmdArgs.push_back("-fexec-charset");
+      CmdArgs.push_back(Args.MakeArgString(Value));
+    } else {
+      D.Diag(diag::err_drv_invalid_value)
+          << ExecEncoding->getAsString(Args) << Value;
     }
-    CmdArgs.push_back("-fexec-charset");
-    CmdArgs.push_back(Args.MakeArgString(Value));
   } else {
     // Set the default fexec-charset as the system charset.
     CmdArgs.push_back("-fexec-charset");
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index ce5030240e133..d0f6b79500fe0 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1776,7 +1776,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   HadError = false;
 
   Kind = kind;
-  const TextEncodingConfig TEC = PP.getTextEncodingConfig();
+  const TextEncodingConfig &TEC = PP.getTextEncodingConfig();
 
   const char *TokBegin = begin;
 
diff --git a/llvm/include/llvm/Support/TextEncoding.h b/llvm/include/llvm/Support/TextEncoding.h
index bda6f2a088eb2..3d31505c5bc6b 100644
--- a/llvm/include/llvm/Support/TextEncoding.h
+++ b/llvm/include/llvm/Support/TextEncoding.h
@@ -136,8 +136,7 @@ class TextEncodingConverter {
     return EC;
   }
 
-  // Maps the encoding name to enum constant if possible.
-  static std::optional<TextEncoding> getKnownEncoding(StringRef Name);
+  LLVM_ABI static bool isEncodingSupported(StringRef Name);
 };
 
 } // namespace llvm
diff --git a/llvm/include/llvm/TargetParser/Triple.h b/llvm/include/llvm/TargetParser/Triple.h
index 192647977db76..b23dde01ee4e2 100644
--- a/llvm/include/llvm/TargetParser/Triple.h
+++ b/llvm/include/llvm/TargetParser/Triple.h
@@ -515,7 +515,7 @@ class Triple {
 
   /// Get the default system encoding of the triple.
   /// For example, "IBM-1047" for z/OS, "UTF-8" for others
-  StringRef getDefaultNarrowTextEncoding() const;
+  LLVM_ABI StringRef getDefaultNarrowTextEncoding() const;
 
   /// @}
   /// @name Convenience Predicates
diff --git a/llvm/lib/Support/TextEncoding.cpp b/llvm/lib/Support/TextEncoding.cpp
index 91bd482ea4a0c..8b98ae373370d 100644
--- a/llvm/lib/Support/TextEncoding.cpp
+++ b/llvm/lib/Support/TextEncoding.cpp
@@ -44,8 +44,7 @@ static void normalizeCharSetName(StringRef CSName,
 }
 
 // Maps the encoding name to enum constant if possible.
-std::optional<TextEncoding>
-TextEncodingConverter::getKnownEncoding(StringRef Name) {
+static std::optional<TextEncoding> getKnownEncoding(StringRef Name) {
   SmallString<16> Normalized;
   normalizeCharSetName(Name, Normalized);
   if (Normalized.equals("utf8"))
@@ -55,6 +54,16 @@ TextEncodingConverter::getKnownEncoding(StringRef Name) {
   return std::nullopt;
 }
 
+bool TextEncodingConverter::isEncodingSupported(StringRef Name) {
+  if (getKnownEncoding(Name))
+    return true;
+  llvm::ErrorOr<llvm::TextEncodingConverter> ErrorOrConverter =
+      llvm::TextEncodingConverter::create("UTF-8", Name.data());
+  if (ErrorOrConverter)
+    return true;
+  return false;
+}
+
 [[maybe_unused]] static void HandleOverflow(size_t &Capacity, char *&Output,
                                             size_t &OutputLength,
                                             SmallVectorImpl<char> &Result) {

>From 84b3a1d8435c06cc3ab6f3a1ff2fb99f616aee09 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Thu, 5 Feb 2026 10:34:49 -0500
Subject: [PATCH 12/15] translate typeinfo to default encoding, address other
 comments

---
 clang/include/clang/Basic/TokenKinds.h | 7 -------
 clang/lib/Lex/TextEncodingConfig.cpp   | 8 ++++----
 2 files changed, 4 insertions(+), 11 deletions(-)

diff --git a/clang/include/clang/Basic/TokenKinds.h b/clang/include/clang/Basic/TokenKinds.h
index a18b81c4dcc26..ace510278186b 100644
--- a/clang/include/clang/Basic/TokenKinds.h
+++ b/clang/include/clang/Basic/TokenKinds.h
@@ -115,13 +115,6 @@ inline bool isLiteral(TokenKind K) {
   return isInLiteralRange;
 }
 
-/// Return true if this is a UTF literal kind.
-inline bool isUTFLiteral(TokenKind K) {
-  return K == tok::utf8_char_constant || K == tok::utf8_string_literal ||
-         K == tok::utf16_char_constant || K == tok::utf16_string_literal ||
-         K == tok::utf32_char_constant || K == tok::utf32_string_literal;
-}
-
 /// Return true if this is a wide literal kind.
 inline bool isWideLiteral(TokenKind K) {
   return K == tok::wide_char_constant || K == tok::wide_string_literal;
diff --git a/clang/lib/Lex/TextEncodingConfig.cpp b/clang/lib/Lex/TextEncodingConfig.cpp
index b8e5109241128..4a1fc477c4ade 100644
--- a/clang/lib/Lex/TextEncodingConfig.cpp
+++ b/clang/lib/Lex/TextEncodingConfig.cpp
@@ -38,10 +38,10 @@ TextEncodingConfig::setConvertersFromOptions(TextEncodingConfig &TEC,
     ErrorOr<TextEncodingConverter> ErrorOrConverter =
         llvm::TextEncodingConverter::create(TEC.InternalEncoding,
                                             TEC.SystemEncoding);
-    if (ErrorOrConverter) {
+    if (ErrorOrConverter)
       TEC.ToSystemEncodingConverter =
           new TextEncodingConverter(std::move(*ErrorOrConverter));
-    } else
+    else
       return ErrorOrConverter.getError();
   }
 
@@ -52,10 +52,10 @@ TextEncodingConfig::setConvertersFromOptions(TextEncodingConfig &TEC,
   ErrorOr<TextEncodingConverter> ErrorOrConverter =
       llvm::TextEncodingConverter::create(TEC.InternalEncoding,
                                           TEC.ExecEncoding);
-  if (ErrorOrConverter) {
+  if (ErrorOrConverter)
     TEC.ToExecEncodingConverter =
         new TextEncodingConverter(std::move(*ErrorOrConverter));
-  } else
+  else
     return ErrorOrConverter.getError();
   return std::error_code();
 }

>From 3715ec00258784ea664c7b3b1ffd4a7a83afa3a7 Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Wed, 11 Feb 2026 14:01:19 -0500
Subject: [PATCH 13/15] remove ToSystemEncodingConverter, support translating
 multibyte characters to single byte in the exec encoding

---
 clang/include/clang/Lex/TextEncodingConfig.h |  7 +------
 clang/lib/Lex/LiteralSupport.cpp             | 19 ++++++++++---------
 clang/lib/Lex/TextEncodingConfig.cpp         | 14 --------------
 clang/test/CodeGen/systemz-charset.c         | 10 +++++++++-
 4 files changed, 20 insertions(+), 30 deletions(-)

diff --git a/clang/include/clang/Lex/TextEncodingConfig.h b/clang/include/clang/Lex/TextEncodingConfig.h
index 492551571ae70..8a10122e9bb37 100644
--- a/clang/include/clang/Lex/TextEncodingConfig.h
+++ b/clang/include/clang/Lex/TextEncodingConfig.h
@@ -16,17 +16,12 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/TextEncoding.h"
 
-enum ConversionAction {
-  CA_NoConversion,
-  CA_ToSystemEncoding,
-  CA_ToExecEncoding
-};
+enum ConversionAction { CA_NoConversion, CA_ToExecEncoding };
 
 class TextEncodingConfig {
   llvm::StringRef InternalEncoding;
   llvm::StringRef SystemEncoding;
   llvm::StringRef ExecEncoding;
-  llvm::TextEncodingConverter *ToSystemEncodingConverter = nullptr;
   llvm::TextEncodingConverter *ToExecEncodingConverter = nullptr;
 
 public:
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index d0f6b79500fe0..e5dd72cf4e143 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -1826,6 +1826,10 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   uint32_t *buffer_begin = &codepoint_buffer.front();
   uint32_t *buffer_end = buffer_begin + codepoint_buffer.size();
 
+  llvm::TextEncodingConverter *Converter = nullptr;
+  if (isOrdinary())
+    Converter = TEC.getConverter(CA_ToExecEncoding);
+
   // Unicode escapes representing characters that cannot be correctly
   // represented in a single code unit are disallowed in character literals
   // by this implementation.
@@ -1840,13 +1844,9 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
   } else if (tok::utf32_char_constant == Kind) {
     largest_character_for_kind = 0x10FFFF;
   } else {
-    largest_character_for_kind = 0x7Fu;
+    largest_character_for_kind = (Converter == nullptr) ? 0x7Fu : 0xFFu;
   }
 
-  llvm::TextEncodingConverter *Converter = nullptr;
-  if (isOrdinary())
-    Converter = TEC.getConverter(CA_ToExecEncoding);
-
   while (begin != end) {
     // Is this a span of non-escape characters?
     if (begin[0] != '\\') {
@@ -1887,10 +1887,11 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
           if (!HadError && Converter) {
             assert(Kind != tok::wide_char_constant &&
                    "Wide character translation not supported");
-            char ByteChar = *tmp_out_start;
+            std::string UTF8String;
+            convertUTF32ToUTF8String(
+                ArrayRef<char>((const char *)tmp_out_start, 4), UTF8String);
             SmallString<1> ConvertedChar;
-            std::error_code EC =
-                Converter->convert(StringRef(&ByteChar, 1), ConvertedChar);
+            std::error_code EC = Converter->convert(UTF8String, ConvertedChar);
             if (EC) {
               PP.Diag(Loc, diag::err_exec_charset_conversion_failed)
                   << EC.message();
@@ -1898,7 +1899,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
             } else {
               if (ConvertedChar.size() > 1)
                 PP.Diag(Loc, diag::err_char_size_increased_after_conversion)
-                    << ByteChar;
+                    << UTF8String;
               *tmp_out_start = ConvertedChar[0];
             }
           }
diff --git a/clang/lib/Lex/TextEncodingConfig.cpp b/clang/lib/Lex/TextEncodingConfig.cpp
index 4a1fc477c4ade..8dff4063fe481 100644
--- a/clang/lib/Lex/TextEncodingConfig.cpp
+++ b/clang/lib/Lex/TextEncodingConfig.cpp
@@ -14,8 +14,6 @@ using namespace llvm;
 llvm::TextEncodingConverter *
 TextEncodingConfig::getConverter(ConversionAction Action) const {
   switch (Action) {
-  case CA_ToSystemEncoding:
-    return ToSystemEncodingConverter;
   case CA_ToExecEncoding:
     return ToExecEncodingConverter;
   default:
@@ -33,18 +31,6 @@ TextEncodingConfig::setConvertersFromOptions(TextEncodingConfig &TEC,
   TEC.ExecEncoding =
       Opts.ExecEncoding.empty() ? TEC.InternalEncoding : Opts.ExecEncoding;
 
-  // Create converter between internal and system encoding
-  if (TEC.InternalEncoding != TEC.SystemEncoding) {
-    ErrorOr<TextEncodingConverter> ErrorOrConverter =
-        llvm::TextEncodingConverter::create(TEC.InternalEncoding,
-                                            TEC.SystemEncoding);
-    if (ErrorOrConverter)
-      TEC.ToSystemEncodingConverter =
-          new TextEncodingConverter(std::move(*ErrorOrConverter));
-    else
-      return ErrorOrConverter.getError();
-  }
-
   // Create converter between internal and exec encoding specified
   // in fexec-charset option.
   if (TEC.InternalEncoding == TEC.ExecEncoding)
diff --git a/clang/test/CodeGen/systemz-charset.c b/clang/test/CodeGen/systemz-charset.c
index c68c58219c2af..33d9ec32d533e 100644
--- a/clang/test/CodeGen/systemz-charset.c
+++ b/clang/test/CodeGen/systemz-charset.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 %s -emit-llvm -triple s390x-none-zos -fexec-charset IBM-1047 -o - | FileCheck %s
 // RUN: %clang %s -emit-llvm -S -target s390x-ibm-zos -o - | FileCheck %s
-// RUN: %clang_cc1 %s -emit-llvm -triple s390x-none-zos -fexec-charset UTF-8 -o - | FileCheck %s --check-prefix=CHECK-UTF8
+// RUN: %clang_cc1 %s -emit-llvm -triple s390x-none-zos -fexec-charset UTF-8 -DIBM1047_ONLY=1 -o - | FileCheck %s --check-prefix=CHECK-UTF8
 
 const char *UpperCaseLetters = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
 //CHECK: c"\C1\C2\C3\C4\C5\C6\C7\C8\C9\D1\D2\D3\D4\D5\D6\D7\D8\D9\E2\E3\E4\E5\E6\E7\E8\E9\00"
@@ -38,6 +38,14 @@ const char singleChar = 'a';
 //CHECK: i8 -127
 //CHECK-UTF8: 97
 
+#ifndef IBM1047_ONLY
+const char cent = '¢';
+//CHECK: i8 74
+
+const char currency = '¤';
+//CHECK: i8 -97
+#endif
+
 const char *UcnCharacters = "\u00E2\u00AC\U000000DF";
 //CHECK: c"B\B0Y\00"
 //CHECK-UTF8: c"\C3\A2\C2\AC\C3\9F\00"

>From 2755287cda7e4a11160c77b151cf682dc356c3ef Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Wed, 11 Feb 2026 14:22:51 -0500
Subject: [PATCH 14/15] add test for cc1 error

---
 clang/test/CodeGen/systemz-charset.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/clang/test/CodeGen/systemz-charset.c b/clang/test/CodeGen/systemz-charset.c
index 33d9ec32d533e..3bfe0890f0b4a 100644
--- a/clang/test/CodeGen/systemz-charset.c
+++ b/clang/test/CodeGen/systemz-charset.c
@@ -53,3 +53,7 @@ const char *UcnCharacters = "\u00E2\u00AC\U000000DF";
 const char *Unicode = "ÿ";
 //CHECK: c"\DF\00"
 //CHECK-UTF8: c"\C3\BF\00"
+
+// RUN: not %clang_cc1 -fexec-charset invalid %s 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
+// CHECK-ERROR: error: failed to configure the text encoding config
+

>From a8be1dec0937e1fceccac8085af68270a19d745a Mon Sep 17 00:00:00 2001
From: Abhina Sreeskantharajan <Abhina.Sreeskantharajan at ibm.com>
Date: Fri, 27 Feb 2026 09:00:13 -0500
Subject: [PATCH 15/15] address comments

---
 .../clang/Basic/DiagnosticDriverKinds.td      |   2 +
 .../clang/Basic/DiagnosticFrontendKinds.td    |   3 +-
 clang/include/clang/Lex/LiteralSupport.h      |   3 +-
 clang/include/clang/Lex/TextEncodingConfig.h  |   4 +-
 clang/lib/Driver/ToolChains/Clang.cpp         |   4 +-
 clang/lib/Frontend/CompilerInstance.cpp       |   7 +-
 clang/lib/Lex/LiteralSupport.cpp              | 143 +++++++-----------
 clang/lib/Lex/TextEncodingConfig.cpp          |  11 +-
 clang/test/CodeGen/systemz-charset.c          |   2 +-
 clang/test/Driver/cl-options.c                |   2 +-
 clang/test/Driver/clang_f_opts.c              |   2 +-
 11 files changed, 73 insertions(+), 110 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 90a92b1602231..e3736e99a9c57 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -149,6 +149,8 @@ def warn_drv_unsupported_option_part_for_target : Warning<
   InGroup<OptionIgnored>;
 def err_drv_unsupported_option_part_for_target : Error<
   "'%0' in '%1' option is not currently supported for target '%2'">;
+def err_drv_unsupported_encoding_for_target
+    : Error<"'%0' is not a supported encoding in target '%1'">;
 def warn_drv_invalid_argument_for_flang : Warning<
   "'%0' is not valid for Fortran">,
   InGroup<OptionIgnored>;
diff --git a/clang/include/clang/Basic/DiagnosticFrontendKinds.td b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
index 33bc20bfb4cc0..e7c6a52a8284e 100644
--- a/clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ b/clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -338,8 +338,7 @@ def err_non_default_visibility_dllimport : Error<
   "non-default visibility cannot be applied to 'dllimport' declaration">;
 def err_ifunc_resolver_return : Error<
   "ifunc resolver function must return a pointer">;
-def err_fe_text_encoding_config
-    : Error<"failed to configure the text encoding config">;
+def err_fe_text_encoding_config : Error<"failed to set fexec-charset to '%0'">;
 def warn_atomic_op_misaligned : Warning<
   "misaligned atomic operation may incur "
   "significant performance penalty"
diff --git a/clang/include/clang/Lex/LiteralSupport.h b/clang/include/clang/Lex/LiteralSupport.h
index 4af60814668e6..6b404403ed95f 100644
--- a/clang/include/clang/Lex/LiteralSupport.h
+++ b/clang/include/clang/Lex/LiteralSupport.h
@@ -311,7 +311,8 @@ class StringLiteralParser {
 private:
   void init(ArrayRef<Token> StringToks, ConversionAction Action);
   bool CopyStringFragment(const Token &Tok, const char *TokBegin,
-                          StringRef Fragment);
+                          StringRef Fragment,
+                          llvm::TextEncodingConverter *Converter);
   void DiagnoseLexingError(SourceLocation Loc);
 };
 
diff --git a/clang/include/clang/Lex/TextEncodingConfig.h b/clang/include/clang/Lex/TextEncodingConfig.h
index 8a10122e9bb37..a785edea923de 100644
--- a/clang/include/clang/Lex/TextEncodingConfig.h
+++ b/clang/include/clang/Lex/TextEncodingConfig.h
@@ -19,8 +19,6 @@
 enum ConversionAction { CA_NoConversion, CA_ToExecEncoding };
 
 class TextEncodingConfig {
-  llvm::StringRef InternalEncoding;
-  llvm::StringRef SystemEncoding;
   llvm::StringRef ExecEncoding;
   llvm::TextEncodingConverter *ToExecEncodingConverter = nullptr;
 
@@ -30,6 +28,8 @@ class TextEncodingConfig {
   setConvertersFromOptions(TextEncodingConfig &TEC,
                            const clang::LangOptions &Opts,
                            const clang::TargetInfo &TInfo);
+
+  llvm::StringRef getExecEncoding() { return ExecEncoding; }
 };
 
 #endif
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index e2de73313f42e..8873d3735d0c9 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -7571,8 +7571,8 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back("-fexec-charset");
       CmdArgs.push_back(Args.MakeArgString(Value));
     } else {
-      D.Diag(diag::err_drv_invalid_value)
-          << ExecEncoding->getAsString(Args) << Value;
+      D.Diag(diag::err_drv_unsupported_encoding_for_target)
+          << Value << Triple.getTriple();
     }
   } else {
     // Set the default fexec-charset as the system charset.
diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 9d523d096f47d..b6cc6c8c60a05 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -546,9 +546,10 @@ void CompilerInstance::createPreprocessor(TranslationUnitKind TUKind) {
   if (GetDependencyDirectives)
     PP->setDependencyDirectivesGetter(*GetDependencyDirectives);
 
-  if (TextEncodingConfig::setConvertersFromOptions(PP->getTextEncodingConfig(),
-                                                   getLangOpts(), getTarget()))
-    PP->getDiagnostics().Report(clang::diag::err_fe_text_encoding_config);
+  if (auto EC = TextEncodingConfig::setConvertersFromOptions(
+          PP->getTextEncodingConfig(), getLangOpts(), getTarget()))
+    PP->getDiagnostics().Report(clang::diag::err_fe_text_encoding_config)
+        << PP->getTextEncodingConfig().getExecEncoding();
 }
 
 std::string
diff --git a/clang/lib/Lex/LiteralSupport.cpp b/clang/lib/Lex/LiteralSupport.cpp
index e5dd72cf4e143..3838d42d9482b 100644
--- a/clang/lib/Lex/LiteralSupport.cpp
+++ b/clang/lib/Lex/LiteralSupport.cpp
@@ -126,6 +126,17 @@ static bool IsEscapeValidInUnevaluatedStringLiteral(char Escape) {
   return false;
 }
 
+static llvm::ErrorOr<char>
+convertCharacter(StringRef Char, llvm::TextEncodingConverter *Converter) {
+  SmallString<8> ResultCharConv;
+  std::error_code EC = Converter->convert(Char, ResultCharConv);
+  if (EC)
+    return EC;
+  else if (ResultCharConv.size() > 1)
+    return std::error_code(E2BIG, std::generic_category());
+  return ResultCharConv[0];
+}
+
 /// ProcessCharEscape - Parse a standard C escape sequence, which can occur in
 /// either a character or a string literal.
 static unsigned ProcessCharEscape(const char *ThisTokBegin,
@@ -376,20 +387,14 @@ static unsigned ProcessCharEscape(const char *ThisTokBegin,
   if (Transcode && Converter) {
     // Invalid escapes are written as '?' and then translated.
     char ByteChar = Invalid ? '?' : ResultChar;
-    SmallString<8> ResultCharConv;
-    std::error_code EC =
-        Converter->convert(StringRef(&ByteChar, 1), ResultCharConv);
-    if (EC) {
+    auto ErrorOrChar = convertCharacter(StringRef(&ByteChar, 1), Converter);
+    if (ErrorOrChar)
+      ResultChar = *ErrorOrChar;
+    else {
       Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
            diag::err_exec_charset_conversion_failed)
-          << EC.message();
+          << ErrorOrChar.getError().message();
       HadError = true;
-    } else {
-      if (ResultCharConv.size() > 1)
-        Diag(Diags, Features, Loc, ThisTokBegin, EscapeBegin, ThisTokBuf,
-             diag::err_char_size_increased_after_conversion)
-            << ByteChar;
-      ResultChar = ResultCharConv[0];
     }
   }
   return ResultChar;
@@ -1885,8 +1890,7 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
             PP.Diag(Loc, diag::err_character_too_large);
           }
           if (!HadError && Converter) {
-            assert(Kind != tok::wide_char_constant &&
-                   "Wide character translation not supported");
+            assert(isOrdinary() && "Only ordinary characters are supported");
             std::string UTF8String;
             convertUTF32ToUTF8String(
                 ArrayRef<char>((const char *)tmp_out_start, 4), UTF8String);
@@ -1897,9 +1901,11 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
                   << EC.message();
               HadError = true;
             } else {
-              if (ConvertedChar.size() > 1)
+              if (ConvertedChar.size() > 1) {
+                HadError = true;
                 PP.Diag(Loc, diag::err_char_size_increased_after_conversion)
                     << UTF8String;
+              }
               *tmp_out_start = ConvertedChar[0];
             }
           }
@@ -1930,20 +1936,14 @@ CharLiteralParser::CharLiteralParser(const char *begin, const char *end,
         assert(ResultPtr - Cp <= 4 &&
                "unexpected result size for UCN escape character");
         if (!HadError) {
-          SmallString<8> CpConv;
-          StringRef ToConvert(Cp, ResultPtr - Cp);
-          std::error_code EC = Converter->convert(StringRef(Cp), CpConv);
-          if (EC) {
+          auto ErrorOrChar =
+              convertCharacter(StringRef(Cp, ResultPtr - Cp), Converter);
+          if (ErrorOrChar)
+            *buffer_begin = *ErrorOrChar;
+          else {
             PP.Diag(Loc, diag::err_exec_charset_conversion_failed)
-                << EC.message();
+                << ErrorOrChar.getError().message();
             HadError = true;
-          } else {
-            if (CpConv.size() > 1) {
-              HadError = true;
-              PP.Diag(Loc, diag::err_character_too_large);
-            } else {
-              *buffer_begin = CpConv[0];
-            }
           }
         }
       }
@@ -2075,42 +2075,6 @@ StringLiteralParser::StringLiteralParser(ArrayRef<Token> StringToks,
   init(StringToks, Action);
 }
 
-static char *convertCharactersInPlace(char *ResultPtr, char *ResultPtrBefore,
-                                      const unsigned CharByteWidth,
-                                      bool &hadError,
-                                      llvm::TextEncodingConverter &Converter) {
-  assert(!hadError && "Unexpected call to convertCharactersInPlace");
-
-  SmallString<256> CpConv;
-  int ResultLength = ResultPtr - ResultPtrBefore;
-  assert(ResultLength % CharByteWidth == 0 &&
-         "Unexpected span of bytes for the characters.");
-  char *Cp = ResultPtrBefore;
-  if (Converter.convert(StringRef(Cp, ResultLength / CharByteWidth), CpConv)) {
-    hadError = true;
-    return ResultPtr;
-  }
-  if (CharByteWidth == 1) {
-    memcpy(Cp, CpConv.data(), CpConv.size());
-    return Cp + CpConv.size();
-  }
-  std::string UTF8String;
-  if (CharByteWidth == 4)
-    convertUTF32ToUTF8String(ArrayRef<char>(Cp, ResultLength), UTF8String);
-  else if (CharByteWidth == 2)
-    convertUTF16ToUTF8String(ArrayRef<char>(Cp, ResultLength), UTF8String);
-  if (Converter.convert(UTF8String, CpConv)) {
-    hadError = true;
-    return ResultPtr;
-  }
-  int NewCharByteWidth = ((int)CpConv.size()) / (ResultLength / CharByteWidth);
-  unsigned EndianOffset = llvm::sys::IsBigEndianHost ? CharByteWidth - 1 : 0;
-  for (int i = 0; i < (int)CpConv.size(); i += NewCharByteWidth)
-    memcpy(Cp + EndianOffset + i * CharByteWidth, CpConv.data() + i,
-           NewCharByteWidth);
-  return Cp + CpConv.size() * CharByteWidth;
-}
-
 void StringLiteralParser::init(ArrayRef<Token> StringToks,
                                ConversionAction Action) {
   // The literal token may have come from an invalid source location (e.g. due
@@ -2317,20 +2281,11 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
         StringRef BeforeCRLF = RemainingTokenSpan.substr(0, CRLFPos);
         StringRef AfterCRLF = RemainingTokenSpan.substr(CRLFPos);
 
-        char *ResultPtrBefore = ResultPtr;
         // Copy everything before the \r\n sequence into the string literal.
-        if (CopyStringFragment(StringToks[i], ThisTokBegin, BeforeCRLF))
+        if (CopyStringFragment(StringToks[i], ThisTokBegin, BeforeCRLF,
+                               Converter))
           hadError = true;
 
-        if (!hadError && Converter) {
-          assert(Kind != tok::wide_string_literal &&
-                 "Wide character translation not supported");
-          ResultPtr = convertCharactersInPlace(
-              ResultPtr, ResultPtrBefore, CharByteWidth, hadError, *Converter);
-          if (hadError && Diags)
-            Diags->Report(StringToks[i].getLocation(),
-                          diag::err_exec_charset_conversion_failed);
-        }
         // Point into the \n inside the \r\n sequence and operate on the
         // remaining portion of the literal.
         RemainingTokenSpan = AfterCRLF.substr(1);
@@ -2365,22 +2320,11 @@ void StringLiteralParser::init(ArrayRef<Token> StringToks,
             ++ThisTokBuf;
           } while (ThisTokBuf != ThisTokEnd && ThisTokBuf[0] != '\\');
 
-          char *ResultPtrBefore = ResultPtr;
           // Copy the character span over.
           if (CopyStringFragment(StringToks[i], ThisTokBegin,
-                                 StringRef(InStart, ThisTokBuf - InStart)))
+                                 StringRef(InStart, ThisTokBuf - InStart),
+                                 Converter))
             hadError = true;
-
-          if (!hadError && Converter) {
-            assert(Kind != tok::wide_string_literal &&
-                   "Wide character translation not supported");
-            ResultPtr =
-                convertCharactersInPlace(ResultPtr, ResultPtrBefore,
-                                         CharByteWidth, hadError, *Converter);
-            if (hadError && Diags)
-              Diags->Report(StringToks[i].getLocation(),
-                            diag::err_exec_charset_conversion_failed);
-          }
           continue;
         }
         // Is this a Universal Character Name escape?
@@ -2479,12 +2423,29 @@ static const char *resyncUTF8(const char *Err, const char *End) {
 /// This function copies from Fragment, which is a sequence of bytes
 /// within Tok's contents (which begin at TokBegin) into ResultPtr.
 /// Performs widening for multi-byte characters.
-bool StringLiteralParser::CopyStringFragment(const Token &Tok,
-                                             const char *TokBegin,
-                                             StringRef Fragment) {
+bool StringLiteralParser::CopyStringFragment(
+    const Token &Tok, const char *TokBegin, StringRef Fragment,
+    llvm::TextEncodingConverter *Converter) {
+
   const llvm::UTF8 *ErrorPtrTmp;
-  if (ConvertUTF8toWide(CharByteWidth, Fragment, ResultPtr, ErrorPtrTmp))
+  if (ConvertUTF8toWide(CharByteWidth, Fragment, ResultPtr, ErrorPtrTmp)) {
+    if (Converter) {
+      assert(isOrdinary() && "Only ordinary literals are supported");
+      SmallString<64> CpConv;
+      char *Cp = ResultPtr - Fragment.size();
+      auto EC = Converter->convert(Fragment, CpConv);
+      if (!EC) {
+        memcpy(Cp, CpConv.data(), CpConv.size());
+        ResultPtr = Cp + CpConv.size();
+      } else { // there was a conversion error
+        if (Diags)
+          Diags->Report(Tok.getLocation(),
+                        diag::err_exec_charset_conversion_failed)
+              << EC.message();
+      }
+    }
     return false;
+  }
 
   // If we see bad encoding for unprefixed string literals, warn and
   // simply copy the byte values, for compatibility with gcc and older
@@ -2602,7 +2563,7 @@ unsigned StringLiteralParser::getOffsetOfStringByte(const Token &Tok,
       ProcessCharEscape(SpellingStart, SpellingPtr, SpellingEnd, HadError,
                         FullSourceLoc(Tok.getLocation(), SM), CharByteWidth * 8,
                         Diags, Features, StringLiteralEvalMethod::Evaluated,
-                        nullptr);
+                        /*TextEncodingConfig=*/nullptr);
       --ByteNo;
     }
     assert(!HadError && "This method isn't valid on erroneous strings");
diff --git a/clang/lib/Lex/TextEncodingConfig.cpp b/clang/lib/Lex/TextEncodingConfig.cpp
index 8dff4063fe481..f511b22f3906f 100644
--- a/clang/lib/Lex/TextEncodingConfig.cpp
+++ b/clang/lib/Lex/TextEncodingConfig.cpp
@@ -26,18 +26,17 @@ TextEncodingConfig::setConvertersFromOptions(TextEncodingConfig &TEC,
                                              const clang::LangOptions &Opts,
                                              const clang::TargetInfo &TInfo) {
   using namespace llvm;
-  TEC.InternalEncoding = "UTF-8";
-  TEC.SystemEncoding = TInfo.getTriple().getDefaultNarrowTextEncoding();
+
+  const char *UTF8 = "UTF-8";
   TEC.ExecEncoding =
-      Opts.ExecEncoding.empty() ? TEC.InternalEncoding : Opts.ExecEncoding;
+      Opts.ExecEncoding.empty() ? UTF8 : Opts.ExecEncoding.c_str();
 
   // Create converter between internal and exec encoding specified
   // in fexec-charset option.
-  if (TEC.InternalEncoding == TEC.ExecEncoding)
+  if (TEC.ExecEncoding == UTF8)
     return std::error_code();
   ErrorOr<TextEncodingConverter> ErrorOrConverter =
-      llvm::TextEncodingConverter::create(TEC.InternalEncoding,
-                                          TEC.ExecEncoding);
+      llvm::TextEncodingConverter::create(UTF8, TEC.ExecEncoding);
   if (ErrorOrConverter)
     TEC.ToExecEncodingConverter =
         new TextEncodingConverter(std::move(*ErrorOrConverter));
diff --git a/clang/test/CodeGen/systemz-charset.c b/clang/test/CodeGen/systemz-charset.c
index 3bfe0890f0b4a..fa5c2ea5ef8d5 100644
--- a/clang/test/CodeGen/systemz-charset.c
+++ b/clang/test/CodeGen/systemz-charset.c
@@ -55,5 +55,5 @@ const char *Unicode = "ÿ";
 //CHECK-UTF8: c"\C3\BF\00"
 
 // RUN: not %clang_cc1 -fexec-charset invalid %s 2>&1 | FileCheck %s --check-prefix=CHECK-ERROR
-// CHECK-ERROR: error: failed to configure the text encoding config
+// CHECK-ERROR: error: failed to set fexec-charset to 'invalid'
 
diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
index caa370934065d..3d48aa6b7f804 100644
--- a/clang/test/Driver/cl-options.c
+++ b/clang/test/Driver/cl-options.c
@@ -252,7 +252,7 @@
 
 // /execution-charset: should warn on invalid charsets.
 // RUN: not %clang_cl /execution-charset:invalid-charset -### -- %s 2>&1 | FileCheck -check-prefix=execution-charset-invalid %s
-// execution-charset-invalid: invalid value 'invalid-charset' in '/execution-charset:invalid-charset'
+// execution-charset-invalid: 'invalid-charset' is not a supported encoding in target
 //
 
 // RUN: %clang_cl /Umymacro -### -- %s 2>&1 | FileCheck -check-prefix=U %s
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index c9d5785783033..5eadf355de367 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -233,7 +233,7 @@
 // CHECK-INVALID-INPUT-CHARSET: error: invalid value 'iso-8859-1' in '-finput-charset=iso-8859-1'
 
 // RUN: not %clang -### -S -fexec-charset=invalid-charset -o /dev/null %s 2>&1 | FileCheck -check-prefix=CHECK-INVALID-EXEC-CHARSET %s
-// CHECK-INVALID-EXEC-CHARSET: error: invalid value 'invalid-charset' in '-fexec-charset=invalid-charset'
+// CHECK-INVALID-EXEC-CHARSET: error: 'invalid-charset' is not a supported encoding in target
 
 // Test that we support the following exec charsets. The preferred MIME name is
 // `IBM1047`, but `IBM-1047` is the name used by z/OS USS utilities such as



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