[clang] ca2351d - [C++20] [Modules] Skip checking ODR for merged context in GMF

[Chuanqi Xu via cfe-commits]

Author: Chuanqi Xu
Date: 2024-08-30T11:45:01+08:00
New Revision: ca2351dd142bac574021f48f135a9f9383c41128

URL: https://github.com/llvm/llvm-project/commit/ca2351dd142bac574021f48f135a9f9383c41128
DIFF: https://github.com/llvm/llvm-project/commit/ca2351dd142bac574021f48f135a9f9383c41128.diff

LOG: [C++20] [Modules] Skip checking ODR for merged context in GMF

Solve https://github.com/clangd/clangd/issues/2094

Due clangd will enable PCH automatically, the previous mechanism to skip
ODR check in GMF may be invalid. This patch fixes this for a case.

Added: 
    clang/test/Modules/skip-func-def-odr-with-pch.cppm

Modified: 
    clang/lib/Serialization/ASTReaderDecl.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index d1b77358d0cde4..9272e23c7da3fc 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -3505,7 +3505,8 @@ ASTDeclReader::FindExistingResult ASTDeclReader::findExisting(NamedDecl *D) {
   // same template specialization into the same CXXRecordDecl.
   auto MergedDCIt = Reader.MergedDeclContexts.find(D->getLexicalDeclContext());
   if (MergedDCIt != Reader.MergedDeclContexts.end() &&
-      !shouldSkipCheckingODR(D) && MergedDCIt->second == D->getDeclContext())
+      !shouldSkipCheckingODR(D) && MergedDCIt->second == D->getDeclContext() &&
+      !shouldSkipCheckingODR(cast<Decl>(D->getDeclContext())))
     Reader.PendingOdrMergeChecks.push_back(D);
 
   return FindExistingResult(Reader, D, /*Existing=*/nullptr,

diff  --git a/clang/test/Modules/skip-func-def-odr-with-pch.cppm b/clang/test/Modules/skip-func-def-odr-with-pch.cppm
new file mode 100644
index 00000000000000..7fb5227d7c61e9
--- /dev/null
+++ b/clang/test/Modules/skip-func-def-odr-with-pch.cppm
@@ -0,0 +1,44 @@
+// RUN: rm -rf %t
+// RUN: mkdir %t
+// RUN: split-file %s %t
+//
+// Testing the behavior of `-fskip-odr-check-in-gmf`
+// RUN: %clang_cc1 -std=c++20 -DDIFFERENT -fskip-odr-check-in-gmf %t/A.cppm -emit-module-interface -o %t/A.pcm
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf -x c++-header %t/foo.h -emit-pch -o %t/foo.pch
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf -include-pch %t/foo.pch %t/B.cppm -emit-module-interface -o %t/B.pcm
+// RUN: %clang_cc1 -std=c++20 -fskip-odr-check-in-gmf -fprebuilt-module-path=%t  \
+// RUN:    %t/C.cpp -verify -fsyntax-only
+
+//--- foo.h
+#ifndef FOO_H
+#define FOO_H
+class A {
+public:
+#ifndef DIFFERENT
+  void func() {
+
+  }
+#endif
+};
+#endif
+
+//--- A.cppm
+module;
+#include "foo.h"
+export module A;
+export using ::A;
+
+//--- B.cppm
+module;
+#include "foo.h"
+export module B;
+export using ::A;
+
+//--- C.cpp
+import A;
+import B;
+// expected-no-diagnostics
+void C() {
+  A a;
+  a.func();
+}