[clang] [clang][Modules] Add explicit PrivateModuleFragmentDecl AST node (PR #223044)

Mahmoud Ahmed via cfe-commits cfe-commits at lists.llvm.org
Sat Sep 12 02:11:38 PDT 2026


https://github.com/anondeveg updated https://github.com/llvm/llvm-project/pull/223044

>From 2c6f6f86046d21125e5b935a1f42175c6be43591 Mon Sep 17 00:00:00 2001
From: Anondev <anondeveg at gmail.com>
Date: Fri, 11 Sep 2026 22:51:40 +0300
Subject: [PATCH] [clang][Modules] Add explicit PrivateModuleFragmentDecl AST
 node

---
 clang/include/clang/AST/Decl.h                | 32 +++++++++++++++++++
 clang/include/clang/AST/RecursiveASTVisitor.h |  1 +
 clang/include/clang/AST/TextNodeDumper.h      |  1 +
 clang/include/clang/Basic/DeclNodes.td        |  1 +
 clang/include/clang/Sema/Template.h           |  5 +--
 .../include/clang/Serialization/ASTBitCodes.h |  5 ++-
 clang/lib/AST/Decl.cpp                        |  9 ++++++
 clang/lib/AST/DeclBase.cpp                    |  1 +
 clang/lib/AST/DeclPrinter.cpp                 |  5 +++
 clang/lib/AST/TextNodeDumper.cpp              |  5 +++
 clang/lib/CodeGen/CGDecl.cpp                  |  1 +
 clang/lib/Parse/Parser.cpp                    |  6 +++-
 clang/lib/Sema/SemaModule.cpp                 |  6 ++--
 clang/lib/Serialization/ASTCommon.cpp         |  1 +
 clang/lib/Serialization/ASTReaderDecl.cpp     | 11 +++++++
 clang/lib/Serialization/ASTWriterDecl.cpp     |  8 +++++
 .../mismatched_global_module_state.cppm       |  5 +++
 17 files changed, 97 insertions(+), 6 deletions(-)
 create mode 100644 clang/test/Modules/mismatched_global_module_state.cppm

diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
index 92050d635e2e0..adbbf75111b08 100644
--- a/clang/include/clang/AST/Decl.h
+++ b/clang/include/clang/AST/Decl.h
@@ -5309,6 +5309,38 @@ class ExportDecl final : public Decl, public DeclContext {
   }
 };
 
+class PrivateModuleFragmentDecl final : public Decl {
+  PrivateModuleFragmentDecl(DeclContext *DC, SourceLocation ModuleLoc,
+                            SourceLocation PrivateLoc, Module *Fragment)
+      : Decl(PrivateModuleFragment, DC, ModuleLoc), Fragment(Fragment),
+        PrivateLoc(PrivateLoc) {}
+  PrivateModuleFragmentDecl(EmptyShell Empty)
+      : Decl(PrivateModuleFragment, Empty) {}
+
+public:
+  Module *Fragment;
+  SourceLocation PrivateLoc;
+
+  static PrivateModuleFragmentDecl *Create(ASTContext &C, DeclContext *DC,
+                                           SourceLocation ModuleLoc,
+                                           SourceLocation PrivateLoc,
+                                           Module *Fragment) {
+    return new (C, DC)
+        PrivateModuleFragmentDecl(DC, ModuleLoc, PrivateLoc, Fragment);
+  }
+  static PrivateModuleFragmentDecl *CreateDeserialized(ASTContext &C,
+                                                       GlobalDeclID ID);
+
+  Module *getFragment() const { return Fragment; }
+  SourceLocation getPrivateLoc() const { return PrivateLoc; }
+  SourceRange getSourceRange() const override LLVM_READONLY {
+    return SourceRange(getLocation(), PrivateLoc);
+  }
+  static bool classof(const Decl *D) {
+    return D->getKind() == Decl::PrivateModuleFragment;
+  }
+};
+
 /// Represents an empty-declaration.
 class EmptyDecl : public Decl {
   EmptyDecl(DeclContext *DC, SourceLocation L) : Decl(Empty, DC, L) {}
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 1f7c8d762e1b5..24371d148a0a6 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -1723,6 +1723,7 @@ DEF_TRAVERSE_DECL(FileScopeAsmDecl,
 DEF_TRAVERSE_DECL(TopLevelStmtDecl, { TRY_TO(TraverseStmt(D->getStmt())); })
 
 DEF_TRAVERSE_DECL(ImportDecl, {})
+DEF_TRAVERSE_DECL(PrivateModuleFragmentDecl, {})
 
 DEF_TRAVERSE_DECL(FriendDecl, {
   // Friend is either decl or a type.
diff --git a/clang/include/clang/AST/TextNodeDumper.h b/clang/include/clang/AST/TextNodeDumper.h
index 1cdd8c37c7fc6..d0c97326f85f0 100644
--- a/clang/include/clang/AST/TextNodeDumper.h
+++ b/clang/include/clang/AST/TextNodeDumper.h
@@ -373,6 +373,7 @@ class TextNodeDumper
   void VisitBindingDecl(const BindingDecl *D);
   void VisitCapturedDecl(const CapturedDecl *D);
   void VisitImportDecl(const ImportDecl *D);
+  void VisitPrivateModuleFragmentDecl(const PrivateModuleFragmentDecl *D);
   void VisitPragmaCommentDecl(const PragmaCommentDecl *D);
   void VisitPragmaDetectMismatchDecl(const PragmaDetectMismatchDecl *D);
   void VisitOMPExecutableDirective(const OMPExecutableDirective *D);
diff --git a/clang/include/clang/Basic/DeclNodes.td b/clang/include/clang/Basic/DeclNodes.td
index 114c6ae5282ef..0e81a32d19d25 100644
--- a/clang/include/clang/Basic/DeclNodes.td
+++ b/clang/include/clang/Basic/DeclNodes.td
@@ -107,6 +107,7 @@ def Block : DeclNode<Decl, "blocks">, DeclContext;
 def OutlinedFunction : DeclNode<Decl>, DeclContext;
 def Captured : DeclNode<Decl>, DeclContext;
 def Import : DeclNode<Decl>;
+def PrivateModuleFragment : DeclNode<Decl>;
 def OMPThreadPrivate : DeclNode<Decl>;
 def OMPGroupPrivate : DeclNode<Decl>;
 def OMPAllocate : DeclNode<Decl>;
diff --git a/clang/include/clang/Sema/Template.h b/clang/include/clang/Sema/Template.h
index 50e950e56c6ca..06ca2f1f368a1 100644
--- a/clang/include/clang/Sema/Template.h
+++ b/clang/include/clang/Sema/Template.h
@@ -634,6 +634,7 @@ enum class TemplateSubstitutionKind : char {
 #define FILESCOPEASM(DERIVED, BASE)
 #define TOPLEVELSTMT(DERIVED, BASE)
 #define IMPORT(DERIVED, BASE)
+#define PRIVATEMODULEFRAGMENT(DERIVED, BASE)
 #define EXPORT(DERIVED, BASE)
 #define LINKAGESPEC(DERIVED, BASE)
 #define OBJCCOMPATIBLEALIAS(DERIVED, BASE)
@@ -645,10 +646,10 @@ enum class TemplateSubstitutionKind : char {
 #define EMPTY(DERIVED, BASE)
 #define LIFETIMEEXTENDEDTEMPORARY(DERIVED, BASE)
 
-// Decls which never appear inside a template.
+    // Decls which never appear inside a template.
 #define OUTLINEDFUNCTION(DERIVED, BASE)
 
-// Decls which use special-case instantiation code.
+    // Decls which use special-case instantiation code.
 #define BLOCK(DERIVED, BASE)
 #define CAPTURED(DERIVED, BASE)
 #define IMPLICITPARAM(DERIVED, BASE)
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 6a52a9e4fa780..722bca1975e40 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -1492,7 +1492,10 @@ enum DeclCode {
   /// An ImportDecl recording a module import.
   DECL_IMPORT,
 
-  /// An OMPThreadPrivateDecl record.
+  /// A PrivateModuleFragmentDecl record.
+  DECL_PRIVATE_MODULE_FRAGMENT,
+
+  /// An OMPThreadPrivateDecl Record.
   DECL_OMP_THREADPRIVATE,
 
   /// An OMPRequiresDecl record.
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 0894097333d73..01af3f08e418f 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -6192,3 +6192,12 @@ bool clang::hasArmZT0State(const FunctionDecl *FD) {
                    FunctionType::ARM_None) ||
          (FD->hasAttr<ArmNewAttr>() && FD->getAttr<ArmNewAttr>()->isNewZT0());
 }
+
+//===----------------------------------------------------------------------===//
+// PrivateModuleFragmentDecl Implementation
+//===----------------------------------------------------------------------===//
+
+PrivateModuleFragmentDecl *
+PrivateModuleFragmentDecl::CreateDeserialized(ASTContext &C, GlobalDeclID ID) {
+  return new (C, ID) PrivateModuleFragmentDecl(EmptyShell());
+}
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 70f61fa57a682..e89ee3e0f3170 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -986,6 +986,7 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
     case Friend:
     case FriendTemplate:
     case AccessSpec:
+    case PrivateModuleFragment:
     case LinkageSpec:
     case Export:
     case FileScopeAsm:
diff --git a/clang/lib/AST/DeclPrinter.cpp b/clang/lib/AST/DeclPrinter.cpp
index 1312ffd080342..3e0ab4b41797c 100644
--- a/clang/lib/AST/DeclPrinter.cpp
+++ b/clang/lib/AST/DeclPrinter.cpp
@@ -78,6 +78,7 @@ namespace {
     void VisitFileScopeAsmDecl(FileScopeAsmDecl *D);
     void VisitTopLevelStmtDecl(TopLevelStmtDecl *D);
     void VisitImportDecl(ImportDecl *D);
+    void VisitPrivateModuleFragmentDecl(PrivateModuleFragmentDecl *D);
     void VisitStaticAssertDecl(StaticAssertDecl *D);
     void VisitNamespaceDecl(NamespaceDecl *D);
     void VisitUsingDirectiveDecl(UsingDirectiveDecl *D);
@@ -1065,6 +1066,10 @@ void DeclPrinter::VisitImportDecl(ImportDecl *D) {
       << ";\n";
 }
 
+void DeclPrinter::VisitPrivateModuleFragmentDecl(PrivateModuleFragmentDecl *D) {
+  Out << "module :private;\n";
+}
+
 void DeclPrinter::VisitStaticAssertDecl(StaticAssertDecl *D) {
   Out << "static_assert(";
   D->getAssertExpr()->printPretty(Out, nullptr, Policy, Indentation, "\n",
diff --git a/clang/lib/AST/TextNodeDumper.cpp b/clang/lib/AST/TextNodeDumper.cpp
index f58cc4f5761b7..60312419fa559 100644
--- a/clang/lib/AST/TextNodeDumper.cpp
+++ b/clang/lib/AST/TextNodeDumper.cpp
@@ -2643,6 +2643,11 @@ void TextNodeDumper::VisitImportDecl(const ImportDecl *D) {
     dumpDeclRef(InitD, "initializer");
 }
 
+void TextNodeDumper::VisitPrivateModuleFragmentDecl(
+    const PrivateModuleFragmentDecl *D) {
+  OS << ' ' << D->getFragment()->getFullModuleName();
+}
+
 void TextNodeDumper::VisitPragmaCommentDecl(const PragmaCommentDecl *D) {
   OS << ' ';
   switch (D->getCommentKind()) {
diff --git a/clang/lib/CodeGen/CGDecl.cpp b/clang/lib/CodeGen/CGDecl.cpp
index b8fae352d41d7..b5a8f9db06de0 100644
--- a/clang/lib/CodeGen/CGDecl.cpp
+++ b/clang/lib/CodeGen/CGDecl.cpp
@@ -128,6 +128,7 @@ void CodeGenFunction::EmitDecl(const Decl &D, bool EvaluateConditionDecl) {
   case Decl::ExplicitInstantiation:
   case Decl::Label:        // __label__ x;
   case Decl::Import:
+  case Decl::PrivateModuleFragment:
   case Decl::MSGuid:    // __declspec(uuid("..."))
   case Decl::UnnamedGlobalConstant:
   case Decl::TemplateParamObject:
diff --git a/clang/lib/Parse/Parser.cpp b/clang/lib/Parse/Parser.cpp
index bad81ea92cd2d..7e7efa0df7cfe 100644
--- a/clang/lib/Parse/Parser.cpp
+++ b/clang/lib/Parse/Parser.cpp
@@ -2360,10 +2360,14 @@ Parser::ParseModuleDecl(Sema::ModuleImportState &ImportState) {
     SourceLocation PrivateLoc = ConsumeToken();
     DiagnoseAndSkipCXX11Attributes();
     ExpectAndConsumeSemi(diag::err_private_module_fragment_expected_semi);
+    auto Result = Actions.ActOnPrivateModuleFragmentDecl(ModuleLoc, PrivateLoc);
+
+    if (!Result)
+      return nullptr;
     ImportState = ImportState == Sema::ModuleImportState::ImportAllowed
                       ? Sema::ModuleImportState::PrivateFragmentImportAllowed
                       : Sema::ModuleImportState::PrivateFragmentImportFinished;
-    return Actions.ActOnPrivateModuleFragmentDecl(ModuleLoc, PrivateLoc);
+    return Result;
   }
 
   SmallVector<IdentifierLoc, 2> Path;
diff --git a/clang/lib/Sema/SemaModule.cpp b/clang/lib/Sema/SemaModule.cpp
index d7a182fe5654c..91983e4dcbb2b 100644
--- a/clang/lib/Sema/SemaModule.cpp
+++ b/clang/lib/Sema/SemaModule.cpp
@@ -565,8 +565,10 @@ Sema::ActOnPrivateModuleFragmentDecl(SourceLocation ModuleLoc,
   TU->setModuleOwnershipKind(Decl::ModuleOwnershipKind::ModulePrivate);
   TU->setLocalOwningModule(PrivateModuleFragment);
 
-  // FIXME: Consider creating an explicit representation of this declaration.
-  return nullptr;
+  auto *PMF = PrivateModuleFragmentDecl::Create(
+      Context, CurContext, ModuleLoc, PrivateLoc, PrivateModuleFragment);
+  CurContext->addDecl(PMF);
+  return ConvertDeclToDeclGroup(PMF);
 }
 
 DeclResult Sema::ActOnModuleImport(SourceLocation StartLoc,
diff --git a/clang/lib/Serialization/ASTCommon.cpp b/clang/lib/Serialization/ASTCommon.cpp
index ca7993adb7d2c..9b2eed7d74b65 100644
--- a/clang/lib/Serialization/ASTCommon.cpp
+++ b/clang/lib/Serialization/ASTCommon.cpp
@@ -446,6 +446,7 @@ bool serialization::isRedeclarableDeclKind(unsigned Kind) {
   case Decl::OutlinedFunction:
   case Decl::Captured:
   case Decl::Import:
+  case Decl::PrivateModuleFragment:
   case Decl::OMPThreadPrivate:
   case Decl::OMPGroupPrivate:
   case Decl::OMPAllocate:
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index e973b7ae71954..00032bd11e790 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -402,6 +402,7 @@ class ASTDeclReader : public DeclVisitor<ASTDeclReader, void> {
   void VisitTopLevelStmtDecl(TopLevelStmtDecl *D);
   void VisitImportDecl(ImportDecl *D);
   void VisitAccessSpecDecl(AccessSpecDecl *D);
+  void VisitPrivateModuleFragmentDecl(PrivateModuleFragmentDecl *D);
   void VisitFriendDecl(FriendDecl *D);
   void VisitFriendTemplateDecl(FriendTemplateDecl *D);
   void VisitStaticAssertDecl(StaticAssertDecl *D);
@@ -2397,6 +2398,13 @@ void ASTDeclReader::VisitImportDecl(ImportDecl *D) {
   Record.skipInts(1); // The number of stored source locations.
 }
 
+void ASTDeclReader::VisitPrivateModuleFragmentDecl(
+    PrivateModuleFragmentDecl *D) {
+  VisitDecl(D);
+  D->Fragment = readModule();
+  D->PrivateLoc = readSourceLocation();
+}
+
 void ASTDeclReader::VisitAccessSpecDecl(AccessSpecDecl *D) {
   VisitDecl(D);
   D->setColonLoc(readSourceLocation());
@@ -4278,6 +4286,9 @@ Decl *ASTReader::ReadDeclRecord(GlobalDeclID ID) {
     // locations.
     D = ImportDecl::CreateDeserialized(Context, ID, Record.back());
     break;
+  case DECL_PRIVATE_MODULE_FRAGMENT:
+    D = PrivateModuleFragmentDecl::CreateDeserialized(Context, ID);
+    break;
   case DECL_OMP_THREADPRIVATE: {
     Record.skipInts(1);
     unsigned NumChildren = Record.readInt();
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index 6f67acf9a6e7e..d75eebf24a287 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -140,6 +140,7 @@ namespace clang {
     void VisitFileScopeAsmDecl(FileScopeAsmDecl *D);
     void VisitTopLevelStmtDecl(TopLevelStmtDecl *D);
     void VisitImportDecl(ImportDecl *D);
+    void VisitPrivateModuleFragmentDecl(PrivateModuleFragmentDecl *D);
     void VisitAccessSpecDecl(AccessSpecDecl *D);
     void VisitFriendDecl(FriendDecl *D);
     void VisitFriendTemplateDecl(FriendTemplateDecl *D);
@@ -1829,6 +1830,13 @@ void ASTDeclWriter::VisitAccessSpecDecl(AccessSpecDecl *D) {
   Record.AddSourceLocation(D->getColonLoc());
   Code = serialization::DECL_ACCESS_SPEC;
 }
+void ASTDeclWriter::VisitPrivateModuleFragmentDecl(
+    PrivateModuleFragmentDecl *D) {
+  VisitDecl(D);
+  Record.push_back(Writer.getSubmoduleID(D->getFragment()));
+  Record.AddSourceLocation(D->getPrivateLoc());
+  Code = serialization::DECL_PRIVATE_MODULE_FRAGMENT;
+}
 
 void ASTDeclWriter::VisitFriendDecl(FriendDecl *D) {
   VisitDecl(D);
diff --git a/clang/test/Modules/mismatched_global_module_state.cppm b/clang/test/Modules/mismatched_global_module_state.cppm
new file mode 100644
index 0000000000000..11cfeca5a96b4
--- /dev/null
+++ b/clang/test/Modules/mismatched_global_module_state.cppm
@@ -0,0 +1,5 @@
+// RUN: %clang_cc1 --std=c++23 -fsyntax-only -verify %s
+// see ISSUE 219950 and PR 223044
+module;
+module :private; // expected-error {{private module fragment declaration with no preceding module declaration}}
+export module Foo;



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