https://github.com/dmpolukhin created
https://github.com/llvm/llvm-project/pull/132214
Changes in #111992 was too broad. This change reduces scope of previous fix.
Unfortunately in clang there is no way to know when redeclaration was craeted
artificially due to AST mergse and when it was the case in the original code.
I'm not sure that this fix covers all cases but at least it should fix
regression in clang-20. The ideas how to fix it better are very wellcome.
>From 91e057bf990e2c454b897982ed0b4e823bb3faba Mon Sep 17 00:00:00 2001
From: Dmitry Polukhin <dmitry.poluk...@gmail.com>
Date: Thu, 20 Mar 2025 06:51:46 -0700
Subject: [PATCH] [clang] Fix for regression #130917
Changes in #111992 was too broad. This change reduces scope of previous
fix. Unfortunately in clang there is no way to know when redeclaration
was craeted artificially due to AST mergse and when it was the case in
the original code.
---
.../lib/Sema/SemaTemplateInstantiateDecl.cpp | 2 +-
.../SemaCXX/friend-default-parameters.cpp | 21 +++++++++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)
create mode 100644 clang/test/SemaCXX/friend-default-parameters.cpp
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 539c2fdb83797..eda5d1151ab19 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2572,7 +2572,7 @@ Decl *TemplateDeclInstantiator::VisitFunctionDecl(
// Friend function defined withing class template may stop being function
// definition during AST merges from different modules, in this case decl
// with function body should be used for instantiation.
- if (isFriend) {
+ if (isFriend && D->hasOwningModule()) {
const FunctionDecl *Defn = nullptr;
if (D->hasBody(Defn)) {
D = const_cast<FunctionDecl *>(Defn);
diff --git a/clang/test/SemaCXX/friend-default-parameters.cpp
b/clang/test/SemaCXX/friend-default-parameters.cpp
new file mode 100644
index 0000000000000..7190477ac496a
--- /dev/null
+++ b/clang/test/SemaCXX/friend-default-parameters.cpp
@@ -0,0 +1,21 @@
+// RUN: %clang_cc1 -std=c++20 -verify -emit-llvm-only %s
+
+template <int>
+void Create(const void* = nullptr);
+
+template <int>
+struct ObjImpl {
+ template <int>
+ friend void ::Create(const void*);
+};
+
+template <int I>
+void Create(const void*) {
+ (void) ObjImpl<I>{};
+}
+
+int main() {
+ Create<42>();
+}
+
+// expected-no-diagnostics
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