[clang] member pointer class qualification fix

[mizvekov]

This fixes a regression introduced in #130537,
which was reported here: #132401 (comment)

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.

[llvmbot]

@llvm/pr-subscribers-clang

Author: Matheus Izvekov (mizvekov)

Changes

This fixes a regression introduced in #130537,
which was reported here: #132401 (comment)

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.

---

Full diff: https://github.com/llvm/llvm-project/pull/142081.diff

2 Files Affected:

• (modified) clang/lib/Sema/SemaTemplateDeduction.cpp (+1-1)
• (modified) clang/test/SemaCXX/member-pointer.cpp (+22)

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