[Clang] Fix handling of qualified id-expressions in unevaluated contexts (#99807)

In #89713, we made qualified, parenthesized id-expression ill-formed in
and address of expressions.

The expected behavior should instead be to form a pointer (rather than a
pointer to member)

The fix has been suggested by @zwuis and the tests by
@hubert-reinterpretcast.

It is worth pointing out that some of these tests seem rejected by all
compilers, however the tests do seem correct.

Fixes #89713
Fixes #40906

---------

Co-authored-by: YanzuoLiu <zwuis@outlook.com>

1 files changed, 8 insertions, 17 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 8d24e34..1a441d9 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -14117,7 +14117,14 @@ QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
       // Okay: we can take the address of a field.
       // Could be a pointer to member, though, if there is an explicit
       // scope qualifier for the class.
-      if (isa<DeclRefExpr>(op) && cast<DeclRefExpr>(op)->getQualifier()) {
+
+      // [C++26] [expr.prim.id.general]
+      // If an id-expression E denotes a non-static non-type member
+      // of some class C [...] and if E is a qualified-id, E is
+      // not the un-parenthesized operand of the unary & operator [...]
+      // the id-expression is transformed into a class member access expression.
+      if (isa<DeclRefExpr>(op) && cast<DeclRefExpr>(op)->getQualifier() &&
+          !isa<ParenExpr>(OrigOp.get())) {
         DeclContext *Ctx = dcl->getDeclContext();
         if (Ctx && Ctx->isRecord()) {
           if (dcl->getType()->isReferenceType()) {
@@ -14127,22 +14134,6 @@ QualType Sema::CheckAddressOfOperand(ExprResult &OrigOp, SourceLocation OpLoc) {
             return QualType();
           }
 
-          // C++11 [expr.unary.op] p4:
-          // A pointer to member is only formed when an explicit & is used and
-          // its operand is a qualified-id not enclosed in parentheses.
-          if (isa<ParenExpr>(OrigOp.get())) {
-            SourceLocation LeftParenLoc = OrigOp.get()->getBeginLoc(),
-                           RightParenLoc = OrigOp.get()->getEndLoc();
-
-            Diag(LeftParenLoc,
-                 diag::err_form_ptr_to_member_from_parenthesized_expr)
-                << SourceRange(OpLoc, RightParenLoc)
-                << FixItHint::CreateRemoval(LeftParenLoc)
-                << FixItHint::CreateRemoval(RightParenLoc);
-
-            // Continuing might lead to better error recovery.
-          }
-
           while (cast<RecordDecl>(Ctx)->isAnonymousStructOrUnion())
             Ctx = Ctx->getParent();