[clang] [clang] Emit bad shift warnings (PR #70307)

[Aaron Ballman via cfe-commits]

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@@ -277,7 +277,9 @@ void dr258(void) {
 void dr261(void) {
   /* This is still an integer constant expression despite the overflow. */
   enum e1 {
-    ex1 = __INT_MAX__ + 1  /* expected-warning {{overflow in expression; result is -2'147'483'648 with type 'int'}} */
+    ex1 = __INT_MAX__ + 1  /* expected-warning {{overflow in expression; result is -2'147'483'648 with type 'int'}}
+                              c89only-error {{expression is not an integer constant expression}}
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AaronBallman wrote:

Same question here as to why this is an error in C89.

https://github.com/llvm/llvm-project/pull/70307