[clang] [clang] implement current direction of CWG2765 for string literal comparisons in constant evaluation (PR #109208)

[Timm Baeder via cfe-commits]

================
@@ -2061,15 +2063,21 @@ static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
   return true;
 }
 
-/// Should this call expression be treated as a no-op?
-static bool IsNoOpCall(const CallExpr *E) {
+/// Should this call expression be treated as forming an opaque constant?
+static bool IsOpaqueConstantCall(const CallExpr *E) {
   unsigned Builtin = E->getBuiltinCallee();
   return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
           Builtin == Builtin::BI__builtin___NSStringMakeConstantString ||
           Builtin == Builtin::BI__builtin_ptrauth_sign_constant ||
           Builtin == Builtin::BI__builtin_function_start);
 }
 
+static bool IsOpaqueConstantCall(const LValue &LVal) {
+  auto *BaseExpr =
+      llvm::dyn_cast_or_null<CallExpr>(LVal.Base.dyn_cast<const Expr *>());
----------------
tbaederr wrote:

```suggestion
  const auto *BaseExpr =
      llvm::dyn_cast_if_present<CallExpr>(LVal.Base.dyn_cast<const Expr *>());
```

https://github.com/llvm/llvm-project/pull/109208