Use generator for UP007 autofix

crates/ruff/resources/test/fixtures/pyupgrade/UP007.py

@@ -95,3 +95,11 @@ def f(x: Optional[str, int : float]) -> None:
 
 def f(x: Optional[int, float]) -> None:
     ...
+
+
+# Regression test for: https://github.com/astral-sh/ruff/issues/7131
+class ServiceRefOrValue:
+    service_specification: Optional[
+        list[ServiceSpecificationRef]
+        | list[ServiceSpecification]
+    ] = None

crates/ruff/src/rules/pyupgrade/rules/use_pep604_annotation.rs

@@ -1,12 +1,8 @@
-use itertools::Either::{Left, Right};
-use itertools::Itertools;
-use ruff_python_ast::{self as ast, Expr};
-
 use ruff_diagnostics::{AutofixKind, Diagnostic, Edit, Fix, Violation};
 use ruff_macros::{derive_message_formats, violation};
+use ruff_python_ast::{self as ast, Constant, Expr, ExprContext, Operator};
 use ruff_python_semantic::analyze::typing::Pep604Operator;
-use ruff_source_file::Locator;
-use ruff_text_size::Ranged;
+use ruff_text_size::{Ranged, TextRange};
 
 use crate::checkers::ast::Checker;
 use crate::registry::AsRule;
@@ -83,7 +79,7 @@ pub(crate) fn use_pep604_annotation(
                     }
                     _ => {
                         diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
-                            optional(slice, checker.locator()),
+                            checker.generator().expr(&optional(slice)),
                             expr.range(),
                         )));
                     }
@@ -100,7 +96,7 @@ pub(crate) fn use_pep604_annotation(
                     }
                     Expr::Tuple(ast::ExprTuple { elts, .. }) => {
                         diagnostic.set_fix(Fix::suggested(Edit::range_replacement(
-                            union(elts, checker.locator()),
+                            checker.generator().expr(&union(elts)),
                             expr.range(),
                         )));
                     }
@@ -119,23 +115,36 @@ pub(crate) fn use_pep604_annotation(
 }
 
 /// Format the expression as a PEP 604-style optional.
-fn optional(expr: &Expr, locator: &Locator) -> String {
-    format!("{} | None", locator.slice(expr))
+fn optional(expr: &Expr) -> Expr {
+    ast::ExprBinOp {
+        left: Box::new(expr.clone()),
+        op: Operator::BitOr,
+        right: Box::new(Expr::Constant(ast::ExprConstant {
+            value: Constant::None,
+            kind: None,
+            range: TextRange::default(),
+        })),
+        range: TextRange::default(),
+    }
+    .into()
 }
 
 /// Format the expressions as a PEP 604-style union.
-fn union(elts: &[Expr], locator: &Locator) -> String {
-    let mut elts = elts
-        .iter()
-        .flat_map(|expr| match expr {
-            Expr::Tuple(ast::ExprTuple { elts, .. }) => Left(elts.iter()),
-            _ => Right(std::iter::once(expr)),
-        })
-        .peekable();
-    if elts.peek().is_none() {
-        "()".to_string()
-    } else {
-        elts.map(|expr| locator.slice(expr)).join(" | ")
+fn union(elts: &[Expr]) -> Expr {
+    match elts {
+        [] => Expr::Tuple(ast::ExprTuple {
+            elts: vec![],
+            ctx: ExprContext::Load,
+            range: TextRange::default(),
+        }),
+        [Expr::Tuple(ast::ExprTuple { elts, .. })] => union(elts),
+        [elt] => elt.clone(),
+        [elt, rest @ ..] => Expr::BinOp(ast::ExprBinOp {
+            left: Box::new(union(&[elt.clone()])),
+            op: Operator::BitOr,
+            right: Box::new(union(rest)),
+            range: TextRange::default(),
+        }),
     }
 }
 

crates/ruff/src/rules/pyupgrade/snapshots/ruff__rules__pyupgrade__tests__UP007.py.snap

@@ -50,7 +50,7 @@ UP007.py:14:10: UP007 [*] Use `X | Y` for type annotations
 12 12 | 
 13 13 | 
 14    |-def f(x: Union[str, int, Union[float, bytes]]) -> None:
-   14 |+def f(x: str | int | Union[float, bytes]) -> None:
+   14 |+def f(x: str | (int | Union[float, bytes])) -> None:
 15 15 |     ...
 16 16 | 
 17 17 | 
@@ -176,7 +176,7 @@ UP007.py:38:11: UP007 [*] Use `X | Y` for type annotations
 36 36 | 
 37 37 | 
 38    |-def f(x: "Union[str, int, Union[float, bytes]]") -> None:
-   38 |+def f(x: "str | int | Union[float, bytes]") -> None:
+   38 |+def f(x: "str | (int | Union[float, bytes])") -> None:
 39 39 |     ...
 40 40 | 
 41 41 | 
@@ -369,4 +369,27 @@ UP007.py:96:10: UP007 Use `X | Y` for type annotations
    |
    = help: Convert to `X | Y`
 
+UP007.py:102:28: UP007 [*] Use `X | Y` for type annotations
+    |
+100 |   # Regression test for: https://github.com/astral-sh/ruff/issues/7131
+101 |   class ServiceRefOrValue:
+102 |       service_specification: Optional[
+    |  ____________________________^
+103 | |         list[ServiceSpecificationRef]
+104 | |         | list[ServiceSpecification]
+105 | |     ] = None
+    | |_____^ UP007
+    |
+    = help: Convert to `X | Y`
+
+ℹ Suggested fix
+99  99  | 
+100 100 | # Regression test for: https://github.com/astral-sh/ruff/issues/7131
+101 101 | class ServiceRefOrValue:
+102     |-    service_specification: Optional[
+103     |-        list[ServiceSpecificationRef]
+104     |-        | list[ServiceSpecification]
+105     |-    ] = None
+    102 |+    service_specification: list[ServiceSpecificationRef] | list[ServiceSpecification] | None = None
+