error message: move star prefix to Argument

[reka]

Move * or ** prefix from argument type to "Argument".

Example

Before:

Argument 1 to "g" has incompatible type "**Dict[str, object]"

After:

**Argument 1 to "g" has incompatible type "Dict[str, object]"

Description

This is the 1st step to fix #8874 :

Move * or ** prefix from argument type to "Argument".

Further possible steps:

1. Include the kwargs variable name (if any) in the error message

test.py:6: error: **Argument 2 ("json_kwargs") to "dumps" has incompatible type "Dict[str, int]"; expected "bool"

2. Include the expected argument's name

test.py:6: error: **Argument 2 to "dumps" has incompatible type "Dict[str, int]"; expected "bool" for "skipkeys"

3. Squash all error messages related to the same argument into one error message.

4. Add a note with possible fixes:

...: note: Consider using a TypedDict type or "Dict[str, Any]" for the ** argument

Test Plan

• No new tests added.
• Updated existing tests.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

vision (https://github.com/pytorch/vision)
- torchvision/datasets/utils.py:71: error: Argument 1 to "md5" has incompatible type "**Dict[str, bool]"; expected "Union[bytes, Union[bytearray, memoryview, array[Any], mmap, _CData, PickleBuffer]]"  [arg-type]
+ torchvision/datasets/utils.py:71: error: **Argument 1 to "md5" has incompatible type "Dict[str, bool]"; expected "Union[bytes, Union[bytearray, memoryview, array[Any], mmap, _CData, PickleBuffer]]"  [arg-type]

pyppeteer (https://github.com/pyppeteer/pyppeteer)
- pyppeteer/launcher.py:149: error: Argument 2 to "Popen" has incompatible type "**Dict[str, Optional[Any]]"; expected "int"
+ pyppeteer/launcher.py:149: error: **Argument 2 to "Popen" has incompatible type "Dict[str, Optional[Any]]"; expected "int"
- pyppeteer/launcher.py:149: error: Argument 2 to "Popen" has incompatible type "**Dict[str, Optional[Any]]"; expected "bool"
+ pyppeteer/launcher.py:149: error: **Argument 2 to "Popen" has incompatible type "Dict[str, Optional[Any]]"; expected "bool"
- pyppeteer/launcher.py:149: error: Argument 2 to "Popen" has incompatible type "**Dict[str, Optional[Any]]"; expected "str"
+ pyppeteer/launcher.py:149: error: **Argument 2 to "Popen" has incompatible type "Dict[str, Optional[Any]]"; expected "str"

discord.py (https://github.com/Rapptz/discord.py)
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "str"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "str"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Iterable[str]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Iterable[str]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "float"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "float"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[float]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[float]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "bool"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "bool"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[BasicAuth]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[BasicAuth]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[str]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[str]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[Mapping[str, str]]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[Mapping[str, str]]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Union[Mapping[Union[str, istr], str], CIMultiDict[str], CIMultiDictProxy[str], None]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Union[Mapping[Union[str, istr], str], CIMultiDict[str], CIMultiDictProxy[str], None]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Union[str, URL, None]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Union[str, URL, None]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Union[SSLContext, bool, Fingerprint, None]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Union[SSLContext, bool, Fingerprint, None]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[bool]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[bool]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[bytes]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[bytes]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[SSLContext]"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "Optional[SSLContext]"
- discord/http.py:376: error: Argument 2 to "ws_connect" of "ClientSession" has incompatible type "**Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "int"
+ discord/http.py:376: error: **Argument 2 to "ws_connect" of "ClientSession" has incompatible type "Dict[str, Union[Dict[str, str], float, BasicAuth, None, str]]"; expected "int"
- discord/client.py:666: error: Argument 2 to "from_client" of "DiscordWebSocket" has incompatible type "**Dict[str, Optional[int]]"; expected "bool"
+ discord/client.py:666: error: **Argument 2 to "from_client" of "DiscordWebSocket" has incompatible type "Dict[str, Optional[int]]"; expected "bool"
- discord/client.py:666: error: Argument 2 to "from_client" of "DiscordWebSocket" has incompatible type "**Dict[str, Optional[int]]"; expected "Optional[str]"
+ discord/client.py:666: error: **Argument 2 to "from_client" of "DiscordWebSocket" has incompatible type "Dict[str, Optional[int]]"; expected "Optional[str]"

[JukkaL]

Thanks for the PR! I think that the error message would be a little clearer like this:

Unpacked argument 1 to "g" has incompatible type "Dict[str, object]"

We can use this message for both *args and **kwargs. What do you think?