[clang] [Clang][Sema] Fix crash when diagnosing near-match for 'constexpr' redeclaration in C++11 (PR #92452)

[Aaron Ballman via cfe-commits]

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@@ -9203,15 +9203,15 @@ static NamedDecl *DiagnoseInvalidRedeclaration(
         << Idx << FDParam->getType()
         << NewFD->getParamDecl(Idx - 1)->getType();
     } else if (FDisConst != NewFDisConst) {
-      SemaRef.Diag(FD->getLocation(), diag::note_member_def_close_const_match)
-          << NewFDisConst << FD->getSourceRange().getEnd()
-          << (NewFDisConst
-                  ? FixItHint::CreateRemoval(ExtraArgs.D.getFunctionTypeInfo()
-                                                 .getConstQualifierLoc())
-                  : FixItHint::CreateInsertion(ExtraArgs.D.getFunctionTypeInfo()
-                                                   .getRParenLoc()
-                                                   .getLocWithOffset(1),
-                                               " const"));
+      auto DB = SemaRef.Diag(FD->getLocation(),
+                             diag::note_member_def_close_const_match)
+                << NewFDisConst << FD->getSourceRange().getEnd();
+      if (const auto &FTI = ExtraArgs.D.getFunctionTypeInfo(); !NewFDisConst)
+        DB << FixItHint::CreateInsertion(FTI.getRParenLoc().getLocWithOffset(1),
+                                         " const");
+      else if (SourceLocation ConstLoc = FTI.getConstQualifierLoc();
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AaronBallman wrote:

I think that hides subtle issues; the caller should really know the difference between "const qualifier as written" and "semantically const".

https://github.com/llvm/llvm-project/pull/92452