Improve error messages for except* (B025, B029, B030, B904) #14791

[smokyabdulrahman]

Improves error message for except* (Rules: B025, B029, B030, B904)

Example python snippet:

try:
    a = 1
except* ValueError:
    a = 2
except* ValueError:
    a = 2

try:
    pass
except* ():
    pass

try:
    pass
except* 1:  # error
    pass

try:
    raise ValueError
except* ValueError:
    raise UserWarning

Error messages
Before:

$ ruff check --select=B foo.py
foo.py:6:9: B025 try-except block with duplicate exception `ValueError`
foo.py:11:1: B029 Using `except ():` with an empty tuple does not catch anything; add exceptions to handle
foo.py:16:9: B030 `except` handlers should only be exception classes or tuples of exception classes
foo.py:22:5: B904 Within an `except` clause, raise exceptions with `raise ... from err` or `raise ... from None` to distinguish them from errors in exception handling
Found 4 errors.

After:

$ ruff check --select=B foo.py
foo.py:6:9: B025 try-except* block with duplicate exception `ValueError`
foo.py:11:1: B029 Using `except* ():` with an empty tuple does not catch anything; add exceptions to handle
foo.py:16:9: B030 `except*` handlers should only be exception classes or tuples of exception classes
foo.py:22:5: B904 Within an `except*` clause, raise exceptions with `raise ... from err` or `raise ... from None` to distinguish them from errors in exception handling
Found 4 errors.

Closes #14791

[charliermarsh]

If you're able, can you run cargo test -p ruff_linter --lib and then cargo insta accept to update the checked-in snapshots? You'll need to run cargo install cargo-insta first.

[smokyabdulrahman]

If you're able, can you run cargo test -p ruff_linter --lib and then cargo insta accept to update the checked-in snapshots? You'll need to run cargo install cargo-insta first.

Yes, sure thing. I've ran the tests locally before committing. However, I didn't know how to accept my test modifications.

Thank you 👌 I will be doing that with in the next commit.

[smokyabdulrahman]

BTW @charliermarsh

Since I am going to fix a couple more rules also. (B025, B029, B030, B904)

Does it make sense to do the following change in the statement parser:

            ExceptHandler::ExceptHandler(ast::ExceptHandlerExceptHandler {
                type_,
                name,
                body: except_body,
                range: self.node_range(start),
                in_trystar: block_kind.is_star(), <---- `try` block kind
            }),

so that in_trystar is accessible in all the rules handlers.
or is that an overkill?

[charliermarsh]

@smokyabdulrahman -- I'd prefer not to change the parser / AST, if possible.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[MichaReiser]

Thank you!

[smokyabdulrahman]

Just for learning purposes. @MichaReiser
Why was this moved inside the diagnostic-branch?

I thought calculating it outside the loop once would be better.