Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters
This comment has been minimized.
This comment has been minimized.
The test suite currently fails due to a previous merge conflict that will be resolved by #19118. The Mypy primer differences are only due to different union item orders. @ilevkivskyi: Would you like to review this simple change? It is a small extension of one of your code sections. |
This comment has been minimized.
This comment has been minimized.
mypy/meet.py Outdated
| narrow_declared_type(x, narrowed) | ||
| for x in declared.relevant_items() | ||
| narrow_declared_type(d, n) | ||
| for d, n in product( |
There was a problem hiding this comment.
This looks like the correct way of doing that, despite higher comp complexity. What's more mypyc-friendly - itertools.product or a plain listcomp with two for clauses?
There was a problem hiding this comment.
I feel like plain listcomp would be faster (we're consuming all the items anyways), but I would be surprised if this is a hot path because there's an is_subtype check -- surely that's somewhat slow!
There was a problem hiding this comment.
Thanks for the feedback!
I have no experience with Mypyc, so I can only guess, and would agree with @A5rocks that the possible overhead of itertools.product (if it exists) should be negligible compared to the cost of the additional calls to narrow_declared_type, is_overlapping_types, and is_subtype.
There was a problem hiding this comment.
itertools.product may not be a significant bottleneck here, but I'd like to avoid it so that new code is less likely to follow the example and add usages in locations where it will be a bottleneck. Also it might slow things down measurably in very simple cases at least, e.g. union of 2 items. I'd prefer to write this using list comprehensions for these reasons.
There was a problem hiding this comment.
Okay, I removed itertools.product. The second-best readable solution that came to mind. No list comprehensions; I hope that's fine.
A5rocks approved these changes Jun 10, 2025
mypy/meet.py Outdated
| narrow_declared_type(x, narrowed) | ||
| for x in declared.relevant_items() | ||
| narrow_declared_type(d, n) | ||
| for d, n in product( |
There was a problem hiding this comment.
I feel like plain listcomp would be faster (we're consuming all the items anyways), but I would be surprised if this is a hot path because there's an is_subtype check -- surely that's somewhat slow!
This comment has been minimized.
This comment has been minimized.
Diff from mypy_primer, showing the effect of this PR on open source code: ibis (https://.com/ibis-project/ibis)
- ibis/backends/mssql/__init__.py:691: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/mssql/__init__.py:691: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/mssql/__init__.py:738: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]"; expected "Schema" [arg-type]
+ ibis/backends/mssql/__init__.py:691: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/mssql/__init__.py:691: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/mssql/__init__.py:738: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any"; expected "Schema" [arg-type]
- ibis/backends/databricks/__init__.py:215: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | None" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/databricks/__init__.py:215: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | None" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/databricks/__init__.py:215: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any | None" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/databricks/__init__.py:215: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any | None" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/databricks/__init__.py:215: error: Item "None" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | None" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/databricks/__init__.py:215: error: Item "None" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any | None" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/risingwave/__init__.py:564: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/risingwave/__init__.py:564: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/risingwave/__init__.py:602: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]"; expected "Schema" [arg-type]
+ ibis/backends/risingwave/__init__.py:564: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/risingwave/__init__.py:564: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/risingwave/__init__.py:602: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any"; expected "Schema" [arg-type]
- ibis/backends/postgres/__init__.py:646: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/postgres/__init__.py:646: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/postgres/__init__.py:678: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]"; expected "Schema" [arg-type]
+ ibis/backends/postgres/__init__.py:646: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/postgres/__init__.py:646: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/postgres/__init__.py:678: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any"; expected "Schema" [arg-type]
- ibis/backends/mysql/__init__.py:411: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/mysql/__init__.py:411: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/mysql/__init__.py:438: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]"; expected "Schema" [arg-type]
+ ibis/backends/mysql/__init__.py:411: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/mysql/__init__.py:411: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/mysql/__init__.py:438: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any"; expected "Schema" [arg-type]
- ibis/backends/exasol/__init__.py:385: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/exasol/__init__.py:385: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/exasol/__init__.py:410: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]"; expected "Schema" [arg-type]
+ ibis/backends/exasol/__init__.py:385: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/exasol/__init__.py:385: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/exasol/__init__.py:410: error: Argument "schema" to "DatabaseTable" has incompatible type "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any"; expected "Schema" [arg-type]
- ibis/backends/duckdb/__init__.py:190: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "null_fields" [union-attr]
- ibis/backends/duckdb/__init__.py:190: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "null_fields" [union-attr]
- ibis/backends/duckdb/__init__.py:203: error: Item "Mapping[str, str | DataType]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
- ibis/backends/duckdb/__init__.py:203: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Any | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]]" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/duckdb/__init__.py:190: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "null_fields" [union-attr]
+ ibis/backends/duckdb/__init__.py:190: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "null_fields" [union-attr]
+ ibis/backends/duckdb/__init__.py:203: error: Item "Mapping[str, str | DataType]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
+ ibis/backends/duckdb/__init__.py:203: error: Item "Iterable[tuple[str, str | DataType]]" of "Schema | Mapping[str, str | DataType] | Iterable[tuple[str, str | DataType]] | Any" has no attribute "to_sqlglot" [union-attr]
pandas (https://.com/pandas-dev/pandas)
- pandas/core/arrays/_mixins.py:150: error: Argument "dtype" to "view" of "ndarray" has incompatible type "ExtensionDtype | dtype[Any]"; expected "dtype[Any] | _HasDType[dtype[Any]]" [arg-type]
+ pandas/core/arrays/_mixins.py:150: error: Argument "dtype" to "view" of "ndarray" has incompatible type "dtype[Any] | ExtensionDtype"; expected "dtype[Any] | _HasDType[dtype[Any]]" [arg-type]
|
Sign up for free to join this conversation on . Already have an account? Sign in to comment
Add this suggestion to a batch that can be applied as a single commit. This suggestion is invalid because no changes were made to the code. Suggestions cannot be applied while the pull request is closed. Suggestions cannot be applied while viewing a subset of changes. Only one suggestion per line can be applied in a batch. Add this suggestion to a batch that can be applied as a single commit. Applying suggestions on deleted lines is not supported. You must change the existing code in this line in order to create a valid suggestion. Outdated suggestions cannot be applied. This suggestion has been applied or marked resolved. Suggestions cannot be applied from pending reviews. Suggestions cannot be applied on multi-line comments. Suggestions cannot be applied while the pull request is queued to merge. Suggestion cannot be applied right now. Please check back later.
Fixes #14987
I was puzzled as to why my previous attempts to avoid false
unreachablewarnings for loops failed for issue #14987. After some debugging, I realised that the underlying problem is that type narrowing does not work with promotions if both the declared type and the constraining type are unions:The fix seems straightforward (but let's see what the Mypy primer says) and is checked by the test cases
testNarrowPromotionsInsideUnions1andtestNarrowPromotionsInsideUnions2.