[llvm-branch-commits] [clang] release/23.x: [C++20] [Modules] Handling merging predefined decls from std (#219151) (PR #219865)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-modules

Author: llvmbot

<details>
<summary>Changes</summary>

Backport 52774473867e49b5891ab9381accf4e5a3ce0024

Requested by: @<!-- -->frederick-vs-ja

---
Full diff: https://github.com/llvm/llvm-project/pull/219865.diff


2 Files Affected:

- (modified) clang/lib/Sema/SemaDecl.cpp (+1-1) 
- (added) clang/test/Modules/pr218152.cppm (+17) 


``````````diff
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 27fe259af3717..6a25a799aa219 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -18387,7 +18387,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
   }
 
   if (getLangOpts().CPlusPlus && Name && DC && StdNamespace &&
-      DC->Equals(getStdNamespace())) {
+      DC->getRedeclContext()->Equals(getStdNamespace())) {
     if (Name->isStr("bad_alloc")) {
       // This is a declaration of or a reference to "std::bad_alloc".
       isStdBadAlloc = true;
diff --git a/clang/test/Modules/pr218152.cppm b/clang/test/Modules/pr218152.cppm
new file mode 100644
index 0000000000000..c7b82372f42d6
--- /dev/null
+++ b/clang/test/Modules/pr218152.cppm
@@ -0,0 +1,17 @@
+// RUN: %clang_cc1 -std=c++20 -fsyntax-only -verify %s
+
+// expected-no-diagnostics
+export module fake_std;
+
+extern "C++" {
+namespace std {
+  using size_t = decltype(sizeof 0);
+  export enum class align_val_t : size_t {};
+} // namespace std
+
+export void *operator new(std::size_t, std::align_val_t);
+
+namespace std {
+void foo() { align_val_t x{}; }
+} // namespace std
+} // extern "C++"

``````````

</details>


https://github.com/llvm/llvm-project/pull/219865