[cfe] Excessive error if enum and another declaration have the same names

[sgrekhov]

enum E {e1;} // CFE: Error: Couldn't find constructor 'E'. Analyzer: Ok

int E = 1; // CFE: Error: 'E' is already declared in this scope. Analyzer: The name 'E' is already defined

Why CFE reports an error on the enum declaration? There is nothing wrong with it. No this issue if to replace an enum by some class declaration (CFE reports an error for the second declaration only if the first declaration is a class).

Dart SDK version: 3.7.0-183.0.dev (dev) (Fri Nov 22 20:03:46 2024 -0800) on "windows_x64"

[lrhn]

The actual error reported for the enum here does look spurious, as if the enum declaration can't find itself. That's not useful.

I would want an error at both declarations - they're both declarations with conflicted names and one being declared before the other doesn't change that. We don't know which one is wrong (or if it's both), but we do know that neither is valid because there is another declaration with the same name.
(That said, all the spec requires is "a compile-time error", meaning that we refuse to let the program run. Anything else is usability, not speciification.)