[clang] 3609e09 - [clang] member pointer class qualification fix (#142081)

[via cfe-commits]

Author: Matheus Izvekov
Date: 2025-05-30T02:25:21-03:00
New Revision: 3609e09aa7ee03ee529e1c4cba0931027d674d8c

URL: https://github.com/llvm/llvm-project/commit/3609e09aa7ee03ee529e1c4cba0931027d674d8c
DIFF: https://github.com/llvm/llvm-project/commit/3609e09aa7ee03ee529e1c4cba0931027d674d8c.diff

LOG: [clang] member pointer class qualification fix (#142081)

This fixes a regression introduced in
https://github.com/llvm/llvm-project/pull/130537,
which was reported here:
https://github.com/llvm/llvm-project/pull/132401#issuecomment-2839690599

When deducing member pointers class, ignore top level qualifiers on the
argument side, since the class portion of a member pointer is a
nested-name-specifier, and these just nominate an entity.

Qualifiers on the parameter side are fine since deduction allows the
parameter side to be more qualified, and these qualifiers won't be part
of the result.

Since this regression was never released, there are no release notes.

Added: 
    

Modified: 
    clang/lib/Sema/SemaTemplateDeduction.cpp
    clang/test/SemaCXX/member-pointer.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
index 51bfca9da4231..5566057cccef8 100644
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -2127,7 +2127,7 @@ static TemplateDeductionResult DeduceTemplateArgumentsByTypeMatch(
         TA = S.Context.getTypeDeclType(MPA->getMostRecentCXXRecordDecl());
       } else {
         NestedNameSpecifier *QA = MPA->getQualifier();
-        TA = QualType(QA->translateToType(S.Context), 0);
+        TA = QualType(QA->translateToType(S.Context), 0).getUnqualifiedType();
       }
       assert(!TA.isNull() && "member pointer with non-type class");
       return DeduceTemplateArgumentsByTypeMatch(

diff  --git a/clang/test/SemaCXX/member-pointer.cpp b/clang/test/SemaCXX/member-pointer.cpp
index c94c26fbcbb28..6bb0686be7403 100644
--- a/clang/test/SemaCXX/member-pointer.cpp
+++ b/clang/test/SemaCXX/member-pointer.cpp
@@ -408,3 +408,25 @@ namespace deduction2 {
     void i() { e(&C::h); }
   };
 } // namespace deduction2
+
+namespace deduction_qualifiers {
+  struct A {
+    int v;
+  };
+  using CA = const A;
+
+  template <class T> void g(const T&, int T::*);
+  template <class T> void h(const T&, int CA::*);
+
+  void test(const A a, A b) {
+    g(a, &A::v);
+    g(a, &CA::v);
+    h(a, &A::v);
+    h(a, &CA::v);
+
+    g(b, &A::v);
+    g(b, &CA::v);
+    h(b, &A::v);
+    h(b, &CA::v);
+  }
+} // namespace deduction_qualifiers