From c7b2fde04d708279fcd9a82fd59eb84290a8955a Mon Sep 17 00:00:00 2001
From: Younan Zhang <zyn7109@gmail.com>
Date: Tue, 20 May 2025 13:48:28 +0800
Subject: [PATCH 1/2] Reapply "[Clang] Profile singly-resolved
 UnresolvedLookupExpr with the declaration" (#140655)

This reverts commit 383e5f3e2da5c11ecbf1482eb0c39df38ac84e59.
---
 clang/docs/ReleaseNotes.rst                       |  1 +
 clang/lib/AST/StmtProfile.cpp                     |  5 ++++-
 .../SemaTemplate/concepts-out-of-line-def.cpp     | 15 +++++++++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index f04cb7b91788c..4c839303f3621 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -741,6 +741,7 @@ Bug Fixes to C++ Support
 - Fixed the handling of pack indexing types in the constraints of a member function redeclaration. (#GH138255)
 - Clang now correctly parses arbitrary order of ``[[]]``, ``__attribute__`` and ``alignas`` attributes for declarations (#GH133107)
 - Fixed a crash when forming an invalid function type in a dependent context. (#GH138657) (#GH115725) (#GH68852)
+- Fixed a function declaration mismatch that caused inconsistencies between concepts and variable template declarations. (#GH139476)
 - Clang no longer segfaults when there is a configuration mismatch between modules and their users (http://crbug.com/400353616).
 - Fix an incorrect deduction when calling an explicit object member function template through an overload set address.
 - Fixed bug in constant evaluation that would allow using the value of a
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index f7d1655f67ed1..19db338f760ba 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -2189,7 +2189,10 @@ StmtProfiler::VisitCXXPseudoDestructorExpr(const CXXPseudoDestructorExpr *S) {
 
 void StmtProfiler::VisitOverloadExpr(const OverloadExpr *S) {
   VisitExpr(S);
-  VisitNestedNameSpecifier(S->getQualifier());
+  if (S->getNumDecls() == 1)
+    VisitDecl(*S->decls_begin());
+  else
+    VisitNestedNameSpecifier(S->getQualifier());
   VisitName(S->getName(), /*TreatAsDecl*/ true);
   ID.AddBoolean(S->hasExplicitTemplateArgs());
   if (S->hasExplicitTemplateArgs())
diff --git a/clang/test/SemaTemplate/concepts-out-of-line-def.cpp b/clang/test/SemaTemplate/concepts-out-of-line-def.cpp
index e5d00491d3fb8..bf505dec0ca14 100644
--- a/clang/test/SemaTemplate/concepts-out-of-line-def.cpp
+++ b/clang/test/SemaTemplate/concepts-out-of-line-def.cpp
@@ -853,3 +853,18 @@ template <int... Ts>
 requires C<Ts...[0]>
 auto TplClass<int>::buggy() -> void {}
 }
+
+namespace GH139476 {
+
+namespace moo {
+  template <typename T>
+  constexpr bool baa = true;
+
+  template <typename T> requires baa<T>
+  void caw();
+}
+
+template <typename T> requires moo::baa<T>
+void moo::caw() {}
+
+}

From a450de85c4a70dbe1bc168d5b7f0c5f603104fa7 Mon Sep 17 00:00:00 2001
From: Younan Zhang <zyn7109@gmail.com>
Date: Tue, 20 May 2025 13:48:50 +0800
Subject: [PATCH 2/2] Only profile Decls for dependent VarTemplates

---
 clang/lib/AST/StmtProfile.cpp         |  9 ++++++---
 clang/test/SemaCXX/exception-spec.cpp | 21 +++++++++++++++++++++
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 19db338f760ba..2f1dec434c30b 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -2189,11 +2189,14 @@ StmtProfiler::VisitCXXPseudoDestructorExpr(const CXXPseudoDestructorExpr *S) {
 
 void StmtProfiler::VisitOverloadExpr(const OverloadExpr *S) {
   VisitExpr(S);
-  if (S->getNumDecls() == 1)
+  bool DescribingDependentVarTemplate =
+      S->getNumDecls() == 1 && isa<VarTemplateDecl>(*S->decls_begin());
+  if (DescribingDependentVarTemplate) {
     VisitDecl(*S->decls_begin());
-  else
+  } else {
     VisitNestedNameSpecifier(S->getQualifier());
-  VisitName(S->getName(), /*TreatAsDecl*/ true);
+    VisitName(S->getName(), /*TreatAsDecl*/ true);
+  }
   ID.AddBoolean(S->hasExplicitTemplateArgs());
   if (S->hasExplicitTemplateArgs())
     VisitTemplateArguments(S->getTemplateArgs(), S->getNumTemplateArgs());
diff --git a/clang/test/SemaCXX/exception-spec.cpp b/clang/test/SemaCXX/exception-spec.cpp
index 6ad19aab397bd..31c691b28da4b 100644
--- a/clang/test/SemaCXX/exception-spec.cpp
+++ b/clang/test/SemaCXX/exception-spec.cpp
@@ -52,3 +52,24 @@ namespace AssignmentOp {
     D2 &operator=(const D2&); // expected-error {{more lax}}
   };
 }
+
+namespace OverloadedFunctions {
+
+template <typename T>
+void f(T&) noexcept;
+
+template <typename T, int N>
+void f(T (&arr)[N]) noexcept(noexcept(f(*arr)));
+
+template <typename T>
+inline void f(T&) noexcept {}
+
+template <typename T, int N>
+inline void f(T (&arr)[N]) noexcept(noexcept(f(*arr))) {}
+
+void g() {
+    int x[1];
+    f(x);
+}
+
+}