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

[Aaron Ballman via cfe-commits]

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@@ -19959,7 +19961,10 @@ bool Sema::DiagRuntimeBehavior(SourceLocation Loc, ArrayRef<const Stmt*> Stmts,
   case ExpressionEvaluationContext::ConstantEvaluated:
   case ExpressionEvaluationContext::ImmediateFunctionContext:
     // Relevant diagnostics should be produced by constant evaluation.
-    break;
+
+    // Solution below works for warnings detected in
+    // Sema::DiagnoseBadShiftValues()
+    return DiagIfReachable(Loc, Stmts, PD);
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AaronBallman wrote:

This seems incorrect to me -- `DiagRuntimeBehavior()` is used to diagnose runtime issues, so we should not be emitting diagnostics for constant evaluations.

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