Disallow no-args generic aliases when using PEP 613 explicit aliases by brianschubert · Pull Request #18173 · python/mypy (original) (raw)
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Per the type system conformance tests, this is ok:
ListAlias = list x = ListAliasint # OK
While this is not:
ListAlias: TypeAlias = list x: ListAlias[int] # E: already specialized
Mypy currently permits both. This PR makes mypy reject the latter case, improving conformance.
As part of this, no-args PEP 613 explicit aliases are no longer eagerly expanded.
(Also removed a stale comment referencing TypeAliasExpr.no_args, which was removed in #15924)
Conformance results diff for this PR (aliases_explicit now passes):
diff --git a/conformance/results/mypy/aliases_explicit.toml b/conformance/results/mypy/aliases_explicit.toml index ee05762..f07e7ad 100644 --- a/conformance/results/mypy/aliases_explicit.toml +++ b/conformance/results/mypy/aliases_explicit.toml @@ -24,11 +24,11 @@ aliases_explicit.py:89: error: Invalid type: try using Literal[1] instead? [val aliases_explicit.py:90: error: Invalid type alias: expression is not a valid type [valid-type] aliases_explicit.py:90: error: Function "list" could always be true in boolean context [truthy-function] aliases_explicit.py:91: error: Invalid type alias: expression is not a valid type [valid-type] +aliases_explicit.py💯 error: Bad number of arguments for type alias, expected 0, given 1 [type-arg] aliases_explicit.py:101: error: "UnionType[list[Any], set[Any]]" not callable [operator] aliases_explicit.py:102: error: Bad number of arguments for type alias, expected 0, given 1 [type-arg] """ -conformance_automated = "Fail" +conformance_automated = "Pass" errors_diff = """ -Line 100: Expected 1 errors """ ignore_errors = ["Function "list" could always be true in boolean context"] diff --git a/conformance/results/mypy/version.toml b/conformance/results/mypy/version.toml index 699a899..1d9b711 100644 --- a/conformance/results/mypy/version.toml +++ b/conformance/results/mypy/version.toml @@ -1,2 +1,2 @@ -version = "mypy 1.14.0+dev.21587f01045246a9ecb54a054a5ba03e20cbbd19" -test_duration = 4.5 +version = "mypy 1.14.0+dev.6563c362fd5ee8e1fbf17775eab5dcad5a0a7459" +test_duration = 5.1
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The psycopg hits are true positives from aliases of the form _GQueue: TypeAlias = queue.Queue inside if TYPE_CHECKING blocks. Pyright already rejects these. It should be simple for them to migrate these to explicit generic aliases a la _GQueue: TypeAlias = queue.Queue[T].
Diff from mypy_primer, showing the effect of this PR on open source code:
psycopg (https://github.com/psycopg/psycopg)
- psycopg/psycopg/_acompat.py:43: error: Bad number of arguments for type alias, expected 0, given 1 [type-arg]
- psycopg/psycopg/_acompat.py:52: error: Returning Any from function declared to return "T" [no-any-return]
- psycopg/psycopg/_acompat.py:55: error: Bad number of arguments for type alias, expected 0, given 1 [type-arg]
- psycopg_pool/psycopg_pool/_acompat.py:63: error: Bad number of arguments for type alias, expected 0, given 1 [type-arg]
- psycopg_pool/psycopg_pool/_acompat.py:72: error: Returning Any from function declared to return "T" [no-any-return]
- psycopg_pool/psycopg_pool/_acompat.py:105: error: Bad number of arguments for type alias, expected 0, given 1 [type-arg]
hauntsaninja added a commit to hauntsaninja/mypy that referenced this pull request
hauntsaninja added a commit that referenced this pull request
This is a partial revert of #18173 to unblock the 1.15 release
Fixes #18488
wesleywright pushed a commit that referenced this pull request
This is a partial revert of #18173 to unblock the 1.15 release
Fixes #18488
x612skm pushed a commit to x612skm/mypy-dev that referenced this pull request
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