[PATCH] D153296: [AST] Stop evaluate constant expression if the condition expression which in switch statement contains errors

[Yurong via Phabricator via cfe-commits]

yronglin added inline comments.


================
Comment at: clang/lib/AST/ExprConstant.cpp:4893
+  // Stop evaluate if E is a RecoveryExpr.
+  if (isa<RecoveryExpr>(E))
+    return false;
----------------
yronglin wrote:
> erichkeane wrote:
> > I'd probably suggest `E->containsErrors()` instead, to cover cases where we're not the 'root' of a recovery expr?  So something like:
> > 
> > `switch(func_call(unknown_value))`
> > 
> > should create a dependent call expr, but would still contain errors.
> Thanks! Use `E->containsErrors()` and added into release note.
Seems check error inside `EvaluateDependentExpr` will missing diagnostic messages.

This case was introduced in D84637
```
constexpr int test5() { // expected-error {{constexpr function never produce}}
  for (;; a++); // expected-error {{use of undeclared identifier}}  \
                   expected-note {{constexpr evaluation hit maximum step limit; possible infinite loop?}}
  return 1;
}
```
```
./main.cpp:2:11: error: use of undeclared identifier 'a'
    2 |   for (;; a++); // expected-error {{use of undeclared identifier}}  \
      |           ^
1 error generated.
```
But I think the `infinite loop` diagnostic is unnecessary, should we update the test case? WDYT?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D153296/new/

https://reviews.llvm.org/D153296