[clang] [clang][Sema] Fix assertion crash on invalid concept template parameter (#225792) (PR #235408)

[Younan Zhang via cfe-commits]

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@@ -1540,7 +1538,36 @@ namespace {
         Designator.setInvalid();
         return;
       }
+
+      if(Base){
+        // Mark invalid and return early if Base points to an invalid decl
+        if(const auto *VD = Base.dyn_cast<const ValueDecl *>()){
+          if(VD->isInvalidDecl()){
+            Designator.setInvalid();
+            return;
+          }
+        }
+        // Mark invalid and return early if Base points to an invalid type
+        QualType BaseTy = getType(Base).getNonReferenceType();
+        if(BaseTy.isNull() || BaseTy->containsErrors() || (!BaseTy->isPointerType() && !BaseTy->isArrayType())){
+          Designator.setInvalid();
+          return;
+        }
+      }
+
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zyn0217 wrote:

Are they relevant to the issue you claim to fix?

https://github.com/llvm/llvm-project/pull/235408