[llvm-branch-commits] [clang] release/22.x: [Clang] Check the underlying type dependency in concept checking guards (PR #184079)

[Younan Zhang via llvm-branch-commits]

https://github.com/zyn0217 created https://github.com/llvm/llvm-project/pull/184079

In the concept parameter mapping patch, we partially preserved sugar for concept checking. However, in dependent contexts there may be non-dependent aliases that still require concept checking to filter out unwanted functions.

This cherry-picks PR 183010 and PR 183226.



>From 8170467841c1d0c2a7a8e9e0a91255736207bdfe Mon Sep 17 00:00:00 2001
From: Younan Zhang <zyn7109 at gmail.com>
Date: Wed, 25 Feb 2026 08:34:35 +0800
Subject: [PATCH] [Clang] Check the underlying type dependency in concept
 checking guards

In the concept parameter mapping patch, we partially preserved sugar for
concept checking. However, in dependent contexts there may be
non-dependent aliases that still require concept checking to filter out
unwanted functions.

This cherry-picks PR 183010 and PR 183226.
---
 clang/include/clang/Sema/Template.h  |  5 +++--
 clang/lib/Sema/SemaConcept.cpp       |  2 +-
 clang/test/SemaTemplate/concepts.cpp | 20 ++++++++++++++++++++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Sema/Template.h b/clang/include/clang/Sema/Template.h
index b0170c21feb1a..0be46e69f1b6f 100644
--- a/clang/include/clang/Sema/Template.h
+++ b/clang/include/clang/Sema/Template.h
@@ -185,12 +185,13 @@ enum class TemplateSubstitutionKind : char {
       return !(*this)(Depth, Index).isNull();
     }
 
-    bool isAnyArgInstantiationDependent() const {
+    bool isAnyArgInstantiationDependent(const ASTContext &C) const {
       for (ArgumentListLevel ListLevel : TemplateArgumentLists)
         for (const TemplateArgument &TA : ListLevel.Args)
           // There might be null template arguments representing unused template
           // parameter mappings in an MLTAL during concept checking.
-          if (!TA.isNull() && TA.isInstantiationDependent())
+          if (!TA.isNull() &&
+              C.getCanonicalTemplateArgument(TA).isInstantiationDependent())
             return true;
       return false;
     }
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index f55f3a9a61ab8..38791940247cb 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -1154,7 +1154,7 @@ static bool CheckConstraintSatisfaction(
     return false;
   }
 
-  if (TemplateArgsLists.isAnyArgInstantiationDependent()) {
+  if (TemplateArgsLists.isAnyArgInstantiationDependent(S.Context)) {
     // No need to check satisfaction for dependent constraint expressions.
     Satisfaction.IsSatisfied = true;
     return false;
diff --git a/clang/test/SemaTemplate/concepts.cpp b/clang/test/SemaTemplate/concepts.cpp
index d93391baf9926..b5fedcbe0b5a7 100644
--- a/clang/test/SemaTemplate/concepts.cpp
+++ b/clang/test/SemaTemplate/concepts.cpp
@@ -1704,6 +1704,26 @@ struct ice_point : relative_point_origin<point<kelvin>> {};
 
 }
 
+namespace GH182344 {
+
+template <typename T>
+  requires true
+void f() {}
+
+template <typename T>
+  requires false
+void f() = delete;
+
+struct Bar {};
+
+template <typename T> using Foo = Bar;
+
+template <typename T> void use() {
+  f<Foo<T>>();
+}
+
+}
+
 namespace GH174667 {
 
 template<class T, class, class U>