Avoid introducing new parentheses in annotated assignments (#8233)

## Summary We decided to avoid changing this in #7315, but it's been reported multiple times (e.g., in #8226, also on Discord). I suggest we change it to improve compatibility. In general, it also seems to lend itself to better code style. Closes #8188 Closes #8226 ## Test Plan Shows improvements for CPython, home-assistant, Poetry, and typeshed. Before: | project | similarity index | total files | changed files | |----------------|------------------:|------------------:|------------------:| | cpython | 0.75803 | 1799 | 1647 | | django | 0.99983 | 2772 | 34 | | home-assistant | 0.99953 | 10596 | 186 | | poetry | 0.99891 | 317 | 17 | | transformers | 0.99966 | 2657 | 330 | | twine | 1.00000 | 33 | 0 | | typeshed | 0.99978 | 3669 | 20 | | warehouse | 0.99977 | 654 | 13 | | zulip | 0.99970 | 1459 | 22 | After: | project | similarity index | total files | changed files | |----------------|------------------:|------------------:|------------------:| | cpython | 0.75804 | 1799 | 1647 | | django | 0.99983 | 2772 | 34 | | home-assistant | 0.99960 | 10596 | 156 | | poetry | 0.99897 | 317 | 17 | | transformers | 0.99966 | 2657 | 330 | | twine | 1.00000 | 33 | 0 | | typeshed | 0.99980 | 3669 | 18 | | warehouse | 0.99977 | 654 | 13 | | zulip | 0.99970 | 1459 | 22 |
astral-sh · Oct 26, 2023 · 88c8b47 · 88c8b47
1 parent 133a745
commit 88c8b47
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diff --git a/crates/ruff_python_formatter/README.md b/crates/ruff_python_formatter/README.md
@@ -537,28 +537,6 @@ def update_emission_strength():
     value = self.emission_strength * 2
 ```
 
-#### Type annotations may be parenthesized when expanded ([#7315](https://github.com/astral-sh/ruff/issues/7315))
-
-Black will avoid parenthesizing type annotations in an annotated assignment, while Ruff will insert
-parentheses in some cases.
-
-For example:
-
-```python
-# Black
-StartElementHandler: Callable[[str, dict[str, str]], Any] | Callable[[str, list[str]], Any] | Callable[
-    [str, dict[str, str], list[str]], Any
-] | None
-
-# Ruff
-StartElementHandler: (
-    Callable[[str, dict[str, str]], Any]
-    | Callable[[str, list[str]], Any]
-    | Callable[[str, dict[str, str], list[str]], Any]
-    | None
-)
-```
-
 #### Call chain calls break differently ([#7051](https://github.com/astral-sh/ruff/issues/7051))
 
 Black occasionally breaks call chains differently than Ruff; in particular, Black occasionally

diff --git a/crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/ann_assign.py b/crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/ann_assign.py
@@ -1,6 +1,21 @@
 # Regression test: Don't forget the parentheses in the value when breaking
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: int = a + 1 * a
 
+bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb: Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb()
+)
+
+bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb: (
+    Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+)= Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb()
+
+JSONSerializable: TypeAlias = (
+    "str | int | float | bool | None | list | tuple | JSONMapping"
+)
+
+JSONSerializable: str | int | float | bool | None | list | tuple | JSONMapping = {1, 2, 3, 4}
+
+JSONSerializable: str | int | float | bool | None | list | tuple | JSONMapping = aaaaaaaaaaaaaaaa
 
 # Regression test: Don't forget the parentheses in the annotation when breaking
 class DefaultRunner:

diff --git a/crates/ruff_python_formatter/src/statement/stmt_ann_assign.rs b/crates/ruff_python_formatter/src/statement/stmt_ann_assign.rs
@@ -21,12 +21,7 @@ impl FormatNodeRule<StmtAnnAssign> for FormatStmtAnnAssign {
 
         write!(
             f,
-            [
-                target.format(),
-                token(":"),
-                space(),
-                maybe_parenthesize_expression(annotation, item, Parenthesize::IfBreaks)
-            ]
+            [target.format(), token(":"), space(), annotation.format(),]
         )?;
 
         if let Some(value) = value {

diff --git a/crates/ruff_python_formatter/tests/snapshots/format@statement__ann_assign.py.snap b/crates/ruff_python_formatter/tests/snapshots/format@statement__ann_assign.py.snap
@@ -7,6 +7,21 @@ input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/statement/
 # Regression test: Don't forget the parentheses in the value when breaking
 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: int = a + 1 * a
 
+bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb: Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb()
+)
+
+bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb: (
+    Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+)= Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb()
+
+JSONSerializable: TypeAlias = (
+    "str | int | float | bool | None | list | tuple | JSONMapping"
+)
+
+JSONSerializable: str | int | float | bool | None | list | tuple | JSONMapping = {1, 2, 3, 4}
+
+JSONSerializable: str | int | float | bool | None | list | tuple | JSONMapping = aaaaaaaaaaaaaaaa
 
 # Regression test: Don't forget the parentheses in the annotation when breaking
 class DefaultRunner:
@@ -20,12 +35,35 @@ aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa: int =
     a + 1 * a
 )
 
+bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb: Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb = (
+    Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb()
+)
+
+bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb: (
+    Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
+) = Bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb()
+
+JSONSerializable: TypeAlias = (
+    "str | int | float | bool | None | list | tuple | JSONMapping"
+)
+
+JSONSerializable: str | int | float | bool | None | list | tuple | JSONMapping = {
+    1,
+    2,
+    3,
+    4,
+}
+
+JSONSerializable: str | int | float | bool | None | list | tuple | JSONMapping = (
+    aaaaaaaaaaaaaaaa
+)
+
 
 # Regression test: Don't forget the parentheses in the annotation when breaking
 class DefaultRunner:
-    task_runner_cls: (
-        TaskRunnerProtocol | typing.Callable[[], typing.Any]
-    ) = DefaultTaskRunner
+    task_runner_cls: TaskRunnerProtocol | typing.Callable[
+        [], typing.Any
+    ] = DefaultTaskRunner
 ```
 
 

diff --git a/docs/formatter/black.md b/docs/formatter/black.md
@@ -399,28 +399,6 @@ def update_emission_strength():
     value = self.emission_strength * 2
 ```
 
-### Type annotations may be parenthesized when expanded
-
-Black will avoid parenthesizing type annotations in an annotated assignment, while Ruff will insert
-parentheses in some cases.
-
-For example:
-
-```python
-# Black
-StartElementHandler: Callable[[str, dict[str, str]], Any] | Callable[[str, list[str]], Any] | Callable[
-    [str, dict[str, str], list[str]], Any
-] | None
-
-# Ruff
-StartElementHandler: (
-    Callable[[str, dict[str, str]], Any]
-    | Callable[[str, list[str]], Any]
-    | Callable[[str, dict[str, str], list[str]], Any]
-    | None
-)
-```
-
 ### Call chain calls break differently
 
 Black occasionally breaks call chains differently than Ruff; in particular, Black occasionally