[llvm-branch-commits] [clang] ac97cff - [C++20] [Modules] Don't diagnose duplicated declarations in different modules which is not in file scope

[Tom Stellard via llvm-branch-commits]

Author: Chuanqi Xu
Date: 2025-02-11T14:05:14-08:00
New Revision: ac97cff5a3684be98f4863191f0006cdf0fa89b4

URL: https://github.com/llvm/llvm-project/commit/ac97cff5a3684be98f4863191f0006cdf0fa89b4
DIFF: https://github.com/llvm/llvm-project/commit/ac97cff5a3684be98f4863191f0006cdf0fa89b4.diff

LOG: [C++20] [Modules] Don't diagnose duplicated declarations in different modules which is not in file scope

Close https://github.com/llvm/llvm-project/issues/126373

Although the root problems should be we shouldn't place the friend
declaration to the incorrect module, let's avoid bleeding the edge by
stoping diagnosing declarations not in file scope.

(cherry picked from commit 569e94f8f1c3e6998860e2b2ff577870433bdac9)

Added: 
    clang/test/Modules/pr126373.cppm

Modified: 
    clang/lib/Serialization/ASTReaderDecl.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 1aa94d5a22abe..8fbb0a8d3edd8 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -3751,6 +3751,13 @@ void ASTDeclReader::checkMultipleDefinitionInNamedModules(ASTReader &Reader,
   if (D->getFriendObjectKind() || Previous->getFriendObjectKind())
     return;
 
+  // Skip diagnosing in-class declarations.
+  if (!Previous->getLexicalDeclContext()
+           ->getNonTransparentContext()
+           ->isFileContext() ||
+      !D->getLexicalDeclContext()->getNonTransparentContext()->isFileContext())
+    return;
+
   Module *M = Previous->getOwningModule();
   if (!M)
     return;

diff  --git a/clang/test/Modules/pr126373.cppm b/clang/test/Modules/pr126373.cppm
new file mode 100644
index 0000000000000..f176a587b51ce
--- /dev/null
+++ b/clang/test/Modules/pr126373.cppm
@@ -0,0 +1,34 @@
+// RUN: rm -rf %t
+// RUN: mkdir -p %t
+// RUN: split-file %s %t
+//
+// RUN: %clang_cc1 -std=c++20 %t/module1.cppm -emit-module-interface -o %t/module1.pcm
+// RUN: %clang_cc1 -std=c++20 -fmodule-file=module1=%t/module1.pcm  %t/module2.cppm \
+// RUN:     -emit-module-interface -o %t/module2.pcm
+// RUN: %clang_cc1 -std=c++20 %t/module2.pcm -fmodule-file=module1=%t/module1.pcm \
+// RUN:     -emit-llvm -o - | FileCheck %t/module2.cppm
+
+//--- test.h
+template<typename T>
+struct Test {
+  template<typename U>
+  friend class Test;
+};
+
+//--- module1.cppm
+module;
+#include "test.h"
+export module module1;
+export void f1(Test<int>) {}
+
+//--- module2.cppm
+module;
+#include "test.h"
+export module module2;
+import module1;
+export void f2(Test<float>) {}
+
+extern "C" void func() {}
+
+// Fine enough to check the IR is emitted correctly.
+// CHECK: define{{.*}}@func