[clang] [clang] Fix elaborated keyword canonicalization (PR #135916)

[Erich Keane via cfe-commits]

================
@@ -1938,6 +1938,17 @@ TagDecl *Type::getAsTagDecl() const {
   return nullptr;
 }
 
+const TemplateSpecializationType *
+Type::getAsNonAliasTemplateSpecializationType() const {
+  for (const auto *T = this; /**/; /**/) {
+    const TemplateSpecializationType *TST =
+        T->getAs<TemplateSpecializationType>();
+    if (!TST || !TST->isTypeAlias())
+      return TST;
+    T = TST->desugar().getTypePtr();
+  }
+}
----------------
erichkeane wrote:

Oof... this is a bit of an abuse of `for` loops/pretending to be a `while`/etc.  What about:

```
const auto *TST = this->getAs<TemplateSpecializationType>();

while (TST && TST->isTypeAlias()) {
  TST = TST->desugar().getTypePTr();
}
return TST;


```

This would probably ALSO prevent any analysis based warnings of 'not all code paths return'.  A little bit of repetition which is not perfect, but perhaps LESS odd?

https://github.com/llvm/llvm-project/pull/135916