[clang] d087d80 - clang-cl: Accept /std:c11, /std:c17 flags

[Nico Weber via cfe-commits]

Author: Nico Weber
Date: 2021-01-29T09:59:00-05:00
New Revision: d087d805acb664e885e9c31a916f6cfa5dbc2186

URL: https://github.com/llvm/llvm-project/commit/d087d805acb664e885e9c31a916f6cfa5dbc2186
DIFF: https://github.com/llvm/llvm-project/commit/d087d805acb664e885e9c31a916f6cfa5dbc2186.diff

LOG: clang-cl: Accept /std:c11, /std:c17 flags

clang-cl already defaults to C17 for .c files, but no harm
in accepting these flags. Fixes PR48185.

Differential Revision: https://reviews.llvm.org/D95575

Added: 
    

Modified: 
    clang/include/clang/Driver/Options.td
    clang/lib/Driver/ToolChains/Clang.cpp
    clang/test/Driver/cl-options.c

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 845f5be55ae7..a13a83eba6d5 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -5604,7 +5604,7 @@ def _SLASH_execution_charset : CLCompileJoined<"execution-charset:">,
   HelpText<"Set runtime encoding, supports only UTF-8">,
   Alias<fexec_charset_EQ>;
 def _SLASH_std : CLCompileJoined<"std:">,
-  HelpText<"Set C++ version (c++14,c++17,c++latest)">;
+  HelpText<"Set language version (c++14,c++17,c++latest,c11,c17)">;
 def _SLASH_U : CLJoinedOrSeparate<"U">, HelpText<"Undefine macro">,
   MetaVarName<"<macro>">, Alias<U>;
 def _SLASH_validate_charset : CLFlag<"validate-charset">,

diff  --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index fdb8a58cd1b3..7bac2b1df17d 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -5204,6 +5204,7 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
   //
   // If a std is supplied, only add -trigraphs if it follows the
   // option.
+  bool ImplyVCPPCVer = false;
   bool ImplyVCPPCXXVer = false;
   const Arg *Std = Args.getLastArg(options::OPT_std_EQ, options::OPT_ansi);
   if (Std) {
@@ -5228,9 +5229,13 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     // doesn't match. For the time being just ignore this for C++ inputs;
     // eventually we want to do all the standard defaulting here instead of
     // splitting it between the driver and clang -cc1.
-    if (!types::isCXX(InputType))
-      Args.AddAllArgsTranslated(CmdArgs, options::OPT_std_default_EQ, "-std=",
-                                /*Joined=*/true);
+    if (!types::isCXX(InputType)) {
+      if (!Args.hasArg(options::OPT__SLASH_std)) {
+        Args.AddAllArgsTranslated(CmdArgs, options::OPT_std_default_EQ, "-std=",
+                                  /*Joined=*/true);
+      } else
+        ImplyVCPPCVer = true;
+    }
     else if (IsWindowsMSVC)
       ImplyVCPPCXXVer = true;
 
@@ -5848,6 +5853,20 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
         Args.MakeArgString("-fms-compatibility-version=" + MSVT.getAsString()));
 
   bool IsMSVC2015Compatible = MSVT.getMajor() >= 19;
+  if (ImplyVCPPCVer) {
+    StringRef LanguageStandard;
+    if (const Arg *StdArg = Args.getLastArg(options::OPT__SLASH_std)) {
+      Std = StdArg;
+      LanguageStandard = llvm::StringSwitch<StringRef>(StdArg->getValue())
+                             .Case("c11", "-std=c11")
+                             .Case("c17", "-std=c17")
+                             .Default("");
+      if (LanguageStandard.empty())
+        D.Diag(clang::diag::warn_drv_unused_argument)
+            << StdArg->getAsString(Args);
+    }
+    CmdArgs.push_back(LanguageStandard.data());
+  }
   if (ImplyVCPPCXXVer) {
     StringRef LanguageStandard;
     if (const Arg *StdArg = Args.getLastArg(options::OPT__SLASH_std)) {

diff  --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
index 73f7026c65e6..226dc446028f 100644
--- a/clang/test/Driver/cl-options.c
+++ b/clang/test/Driver/cl-options.c
@@ -337,6 +337,9 @@
 // RUN: %clang_cl -c -### /Zc:char8_t- -- %s 2>&1 | FileCheck -check-prefix CHECK-CHAR8_T_ %s
 // CHECK-CHAR8_T_: "-fno-char8_t"
 
+// RUN: %clang_cl -c -### /std:c11 -- %s 2>&1 | FileCheck -check-prefix CHECK-C11 %s
+// CHECK-C11: -std=c11
+
 // For some warning ids, we can map from MSVC warning to Clang warning.
 // RUN: %clang_cl -wd4005 -wd4100 -wd4910 -wd4996 -### -- %s 2>&1 | FileCheck -check-prefix=Wno %s
 // Wno: "-cc1"