[clang] [clang] Fix crash in concept deprecation (PR #98622)

[Vlad Serebrennikov via cfe-commits]

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@@ -6308,11 +6308,11 @@ TypeResult Sema::ActOnTypeName(Declarator &D) {
     CheckExtraCXXDefaultArguments(D);
   }
 
-  if (const AutoType *AutoT = T->getAs<AutoType>())
-    CheckConstrainedAuto(
-        AutoT,
-        TInfo->getTypeLoc().getContainedAutoTypeLoc().getConceptNameLoc());
-
+  if (const AutoType *AutoT = T->getAs<AutoType>()) {
+    AutoTypeLoc Loc = TInfo->getTypeLoc().getContainedAutoTypeLoc();
+    CheckConstrainedAuto(AutoT,
+                         Loc ? Loc.getConceptNameLoc() : SourceLocation());
+  }
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Endilll wrote:

Test with constrained auto in trailing return type doesn't pass otherwise:
https://github.com/llvm/llvm-project/blob/2bdcfbe62cb9a08df4b58a17d44be0a3082df053/clang/test/CXX/drs/cwg24xx.cpp#L78-L81

https://github.com/llvm/llvm-project/pull/98622