[`pylint`] Improve diagnostic range for `PLC0206` (#22312)
Summary
--
This PR fixes #14900 by:
- Restricting the diagnostic range from the whole `for` loop to only the
`target in iter` part
- Adding secondary annotations to each use of the `dict[key]` accesses
- Adding a `fix_title` suggesting to use `for key in dict.items()`
I thought this approach sounded slightly nicer than the alternative of
renaming the rule to focus on each indexing operation mentioned in
https://github.com/astral-sh/ruff/issues/14900#issuecomment-2543923625,
but I don't feel too strongly. This was easy to implement with our new
diagnostic infrastructure too.
This produces an example annotation like this:
```
PLC0206 Extracting value from dictionary without calling `.items()`
--> dict_index_missing_items.py:59:5
|
58 | # A case with multiple uses of the value to show off the secondary annotations
59 | for instrument in ORCHESTRA:
| ^^^^^^^^^^^^^^^^^^^^^^^
60 | data = json.dumps(
61 | {
62 | "instrument": instrument,
63 | "section": ORCHESTRA[instrument],
| ---------------------
64 | }
65 | )
66 |
67 | print(f"saving data for {instrument} in {ORCHESTRA[instrument]}")
| ---------------------
68 |
69 | with open(f"{instrument}/{ORCHESTRA[instrument]}.txt", "w") as f:
| ---------------------
70 | f.write(data)
|
help: Use `for instrument, value in ORCHESTRA.items()` instead
```
which I think is a big improvement over:
```
PLC0206 Extracting value from dictionary without calling `.items()`
--> dict_index_missing_items.py:59:1
|
58 | # A case with multiple uses of the value to show off the secondary annotations
59 | / for instrument in ORCHESTRA:
60 | | data = json.dumps(
61 | | {
62 | | "instrument": instrument,
63 | | "section": ORCHESTRA[instrument],
64 | | }
65 | | )
66 | |
67 | | print(f"saving data for {instrument} in {ORCHESTRA[instrument]}")
68 | |
69 | | with open(f"{instrument}/{ORCHESTRA[instrument]}.txt", "w") as f:
70 | | f.write(data)
| |_____________________^
|
```
The secondary annotation feels a bit bare without a message, but I
thought it
might be too busy to include one. Something like `value extracted here`
or
`indexed here` might work if we do want to include a brief message.
To avoid collecting a `Vec` of annotation ranges, I added a `&Checker`
to the
rule's visitor to emit diagnostics as we go instead of at the end.
Test Plan
--
Existing tests, plus a new case showing off multiple secondary
annotations
