After F821 (Undefined name) for "Literal", fix for PYI020 (QuotedAnnotationInStub) is undesirable

[pajod]

Summary

When combined with some other formatting fix, this one is still consistent .. but hardly ever helpful:

ruff check --diff --no-fix --fix --isolated --stdin-filename="r.pyi" --select=PYI020,F821 -- <<<'v: Literal["return", "0o7", "0*3", "int", "foo"]'
--- r.pyi
+++ r.pyi
@@ -1 +1 @@
-v: Literal["return", "0o7", "0*3", "int", "foo"]
+v: Literal["return", 0o7, 0*3, int, foo]

Would fix 4 errors.

NB: Selected F821 only to showcase what is going on. Nothing special about that, just happens to match one case where PYI020 cannot be positively confirmed to be safe to apply.

• Ruff unconditionally assumes any string in a type parameter is a forward annotation #11378

[ntBre]

Is the undesirable part that "return" is still quoted? I also tried this without selecting F821, and I think I got the same result, but I might be missing something there. I'm assuming that return is skipped since it's a keyword. If you omit --diff and --fix, you can see that diagnostics are only emitted for the other entries:

> ruff check --preview --no-fix --isolated --stdin-filename="r.pyi" --select=PYI020 - <<<'v: Literal["return", "0o7", "0*3", "int", "foo"]'
PYI020 [*] Quoted annotations should not be included in stubs
 --> r.pyi:1:22
  |
1 | v: Literal["return", "0o7", "0*3", "int", "foo"]
  |                      ^^^^^
  |
help: Remove quotes
  - v: Literal["return", "0o7", "0*3", "int", "foo"]
1 + v: Literal["return", 0o7, "0*3", "int", "foo"]

PYI020 [*] Quoted annotations should not be included in stubs
 --> r.pyi:1:29
  |
1 | v: Literal["return", "0o7", "0*3", "int", "foo"]
  |                             ^^^^^
  |
help: Remove quotes
  - v: Literal["return", "0o7", "0*3", "int", "foo"]
1 + v: Literal["return", "0o7", 0*3, "int", "foo"]

PYI020 [*] Quoted annotations should not be included in stubs
 --> r.pyi:1:36
  |
1 | v: Literal["return", "0o7", "0*3", "int", "foo"]
  |                                    ^^^^^
  |
help: Remove quotes
  - v: Literal["return", "0o7", "0*3", "int", "foo"]
1 + v: Literal["return", "0o7", "0*3", int, "foo"]

PYI020 [*] Quoted annotations should not be included in stubs
 --> r.pyi:1:43
  |
1 | v: Literal["return", "0o7", "0*3", "int", "foo"]
  |                                           ^^^^^
  |
help: Remove quotes
  - v: Literal["return", "0o7", "0*3", "int", "foo"]
1 + v: Literal["return", "0o7", "0*3", "int", foo]

Found 4 errors.
[*] 4 fixable with the `--fix` option.

[pajod]

Quoted annotations should not be included in stubs

Slightly exaggerated verbosity for the edge case:

Quoted annotations should not be included in stubs, except when expressing string literals, such as with typing.Literal. I know that I have no way of determining if this Literal thing is typing.Literal, but lets assume the common case: it is not. I tested my assumption on the first element and unambiguously failed. So this fix is not safe here, probably because my assumption about what kind of subscript I am dealing with was incorrect. I could stop here, but where is the fun in that? I am going to try the same "fix" on all the other occurrences and their sub-elements. Possibly, some of them are going to produce valid syntax, yet change meaning in less obvious ways. There is never a bad day for users to learn about the --show-traceback option in mypy!

Suggested extra output, conditional on simple identifier name matching (whether actual behavior is changed or not):

hint: Did you mean: `typing.Literal` here?
 --> a.pyi:1:4
1 | v: Literal[3e+9999, "0o8", int, "int" "", .0^.0]
  |    ^^^^^^^