[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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@@ -1527,20 +1527,20 @@ struct DeclaratorChunk {
 
     /// Retrieve the location of the 'const' qualifier.
     SourceLocation getConstQualifierLoc() const {
-      assert(MethodQualifiers);
-      return MethodQualifiers->getConstSpecLoc();
+      return MethodQualifiers ? MethodQualifiers->getConstSpecLoc()
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AaronBallman wrote:

`DeclSpec.h` is basically used only to gather information from the parser, and so from that perspective, I think the `assert` makes sense. If the caller is asking for the location of the `const` qualifier and one wasn't written in source, the caller is doing something out of the ordinary.

I think the fix-it code should be guarded by a call to `hasMethodTypeQualifiers()` instead.

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