Omit tuple parentheses inside comprehensions (#5790)

crates/ruff_python_formatter/resources/test/fixtures/ruff/expression/dict_comp.py

@@ -43,3 +43,35 @@
     if
     gggggggggggggggggggggggggggggggggggggggggggg
 }
+
+# Useful for tuple target (see https://github.com/astral-sh/ruff/issues/5779#issuecomment-1637614763)
+{k: v for a, a, a, a, a, a, a, a, a, a, [a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a]  in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension}
+{k: v for a, a, a, a, a, a, a, a, a, a, (a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a,)  in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension}
+
+# Leading
+{  # Leading
+    k: v  # Trailing
+    for a, a, a, a, a, a, a, a, a, a, (  # Trailing
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,  # Trailing
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,  # Trailing
+    ) in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension  # Trailing
+}  # Trailing
+# Trailing

crates/ruff_python_formatter/src/expression/expr_tuple.rs

@@ -14,6 +14,9 @@ use crate::prelude::*;
 
 #[derive(Eq, PartialEq, Debug, Default)]
 pub enum TupleParentheses {
+    /// Black omits parentheses for tuples inside of comprehensions.
+    Comprehension,
+
     /// Effectively `None` in `Option<Parentheses>`
     #[default]
     Default,
@@ -116,6 +119,13 @@ impl FormatNodeRule<ExprTuple> for FormatExprTuple {
                 parenthesized("(", &ExprSequence::new(item), ")").fmt(f)
             }
             _ => match self.parentheses {
+                TupleParentheses::Comprehension => {
+                    let separator =
+                        format_with(|f| group(&format_args![text(","), space()]).fmt(f));
+                    f.join_with(separator)
+                        .entries(elts.iter().formatted())
+                        .finish()
+                }
                 TupleParentheses::Subscript => group(&ExprSequence::new(item)).fmt(f),
                 _ => parenthesize_if_expands(&ExprSequence::new(item)).fmt(f),
             },

crates/ruff_python_formatter/src/other/comprehension.rs

@@ -1,4 +1,5 @@
 use crate::comments::{leading_comments, trailing_comments};
+use crate::expression::expr_tuple::TupleParentheses;
 use crate::prelude::*;
 use crate::AsFormat;
 use crate::{FormatNodeRule, PyFormatter};
@@ -58,7 +59,7 @@ impl FormatNodeRule<Comprehension> for FormatComprehension {
                 trailing_comments(before_target_comments),
                 group(&format_args!(
                     Spacer(target),
-                    target.format(),
+                    ExprTupleWithoutParentheses(target),
                     in_spacer,
                     leading_comments(before_in_comments),
                     text("in"),
@@ -104,3 +105,17 @@ impl FormatNodeRule<Comprehension> for FormatComprehension {
         Ok(())
     }
 }
+
+struct ExprTupleWithoutParentheses<'a>(&'a Expr);
+
+impl Format<PyFormatContext<'_>> for ExprTupleWithoutParentheses<'_> {
+    fn fmt(&self, f: &mut Formatter<PyFormatContext<'_>>) -> FormatResult<()> {
+        match self.0 {
+            Expr::Tuple(expr_tuple) => expr_tuple
+                .format()
+                .with_options(TupleParentheses::Comprehension)
+                .fmt(f),
+            other => other.format().fmt(f),
+        }
+    }
+}

crates/ruff_python_formatter/tests/snapshots/black_compatibility@simple_cases__expression.py.snap

@@ -314,19 +314,7 @@ last_call()
  ()
  (1,)
  (1, 2)
-@@ -101,7 +108,10 @@
+@@ -115,7 +122,7 @@
- {a: b * -2 for a, b in dictionary.items()}
- {
-     k: v
--    for k, v in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension
-+    for (
-+        k,
-+        v,
-+    ) in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension
- }
- Python3 > Python2 > COBOL
- Life is Life
-@@ -115,7 +125,7 @@
      arg,
      another,
      kwarg="hey",
@@ -335,7 +323,7 @@ last_call()
  )  # note: no trailing comma pre-3.6
  call(*gidgets[:2])
  call(a, *gidgets[:2])
-@@ -152,13 +162,13 @@
+@@ -152,13 +159,13 @@
  slice[0:1]
  slice[0:1:2]
  slice[:]
@@ -352,7 +340,7 @@ last_call()
  numpy[0, :]
  numpy[:, i]
  numpy[0, :2]
-@@ -172,7 +182,7 @@
+@@ -172,7 +179,7 @@
  numpy[1 : c + 1, c]
  numpy[-(c + 1) :, d]
  numpy[:, l[-2]]
@@ -361,10 +349,11 @@ last_call()
  numpy[np.newaxis, :]
  (str or None) if (sys.version_info[0] > (3,)) else (str or bytes or None)
  {"2.7": dead, "3.7": long_live or die_hard}
-@@ -208,24 +218,14 @@
+@@ -207,25 +214,15 @@
+ )
  what_is_up_with_those_new_coord_names = (coord_names | set(vars_to_create)) - set(
      vars_to_remove
- )
+-)
 -result = (
 -    session.query(models.Customer.id)
 -    .filter(
@@ -372,7 +361,7 @@ last_call()
 -    )
 -    .order_by(models.Customer.id.asc())
 -    .all()
--)
+ )
 -result = (
 -    session.query(models.Customer.id)
 -    .filter(
@@ -394,7 +383,7 @@ last_call()
  Ø = set()
  authors.łukasz.say_thanks()
  mapping = {
-@@ -237,10 +237,10 @@
+@@ -237,10 +234,10 @@
  
  
  def gen():
@@ -409,7 +398,7 @@ last_call()
  
  
  async def f():
-@@ -328,13 +328,18 @@
+@@ -328,13 +325,18 @@
  ):
      return True
  if (
@@ -431,7 +420,7 @@ last_call()
      ^ aaaaaaaa.i << aaaaaaaa.k >> aaaaaaaa.l**aaaaaaaa.m // aaaaaaaa.n
  ):
      return True
-@@ -342,7 +347,8 @@
+@@ -342,7 +344,8 @@
      ~aaaaaaaaaaaaaaaa.a
      + aaaaaaaaaaaaaaaa.b
      - aaaaaaaaaaaaaaaa.c * aaaaaaaaaaaaaaaa.d @ aaaaaaaaaaaaaaaa.e
@@ -556,10 +545,7 @@ str or None if (1 if True else 2) else str or bytes or None
 {a: b * -2 for a, b in dictionary.items()}
 {
     k: v
-    for (
+    for k, v in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension
-        k,
-        v,
-    ) in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension
 }
 Python3 > Python2 > COBOL
 Life is Life

crates/ruff_python_formatter/tests/snapshots/format@expression__dict_comp.py.snap

@@ -49,7 +49,38 @@ input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression
     if
     gggggggggggggggggggggggggggggggggggggggggggg
 }
-```
+
+# Useful for tuple target (see https://github.com/astral-sh/ruff/issues/5779#issuecomment-1637614763)
+{k: v for a, a, a, a, a, a, a, a, a, a, [a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a]  in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension}
+{k: v for a, a, a, a, a, a, a, a, a, a, (a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a, a,)  in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension}
+
+# Leading
+{  # Leading
+    k: v  # Trailing
+    for a, a, a, a, a, a, a, a, a, a, (  # Trailing
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,  # Trailing
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,  # Trailing
+    ) in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension  # Trailing
+}  # Trailing
+# Trailing```
 
 ## Output
 ```py
@@ -95,16 +126,97 @@ input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression
         dddddddddddddddddd,
         eeeeeeeeeeeeeeeeeee,
     ]: aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
-    for (
+    for ccccccccccccccccccccccccccccccccccccccc, ddddddddddddddddddd, [
-        ccccccccccccccccccccccccccccccccccccccc,
+        eeeeeeeeeeeeeeeeeeeeee,
-        ddddddddddddddddddd,
+        fffffffffffffffffffffffff,
-        [eeeeeeeeeeeeeeeeeeeeee, fffffffffffffffffffffffff],
+    ] in eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffggggggggggggggggggggghhhhhhhhhhhhhhothermoreeand_even_moreddddddddddddddddddddd
-    ) in eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffggggggggggggggggggggghhhhhhhhhhhhhhothermoreeand_even_moreddddddddddddddddddddd
     if fffffffffffffffffffffffffffffffffffffffffff
     < gggggggggggggggggggggggggggggggggggggggggggggg
     < hhhhhhhhhhhhhhhhhhhhhhhhhh
     if gggggggggggggggggggggggggggggggggggggggggggg
 }
+
+# Useful for tuple target (see https://github.com/astral-sh/ruff/issues/5779#issuecomment-1637614763)
+{
+    k: v
+    for a, a, a, a, a, a, a, a, a, a, [
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+    ] in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension
+}
+{
+    k: v
+    for a, a, a, a, a, a, a, a, a, a, (
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+    ) in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension
+}
+
+# Leading
+{
+    # Leading
+    k: v  # Trailing
+    for a, a, a, a, a, a, a, a, a, a, (
+        # Trailing
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,  # Trailing
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,
+        a,  # Trailing
+    ) in this_is_a_very_long_variable_which_will_cause_a_trailing_comma_which_breaks_the_comprehension  # Trailing
+}  # Trailing
+# Trailing
 ```
 
 

crates/ruff_python_formatter/tests/snapshots/format@expression__list_comp.py.snap

@@ -92,11 +92,10 @@ input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
     + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
     + [dddddddddddddddddd, eeeeeeeeeeeeeeeeeee]
-    for (
+    for ccccccccccccccccccccccccccccccccccccccc, ddddddddddddddddddd, [
-        ccccccccccccccccccccccccccccccccccccccc,
+        eeeeeeeeeeeeeeeeeeeeee,
-        ddddddddddddddddddd,
+        fffffffffffffffffffffffff,
-        [eeeeeeeeeeeeeeeeeeeeee, fffffffffffffffffffffffff],
+    ] in eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffggggggggggggggggggggghhhhhhhhhhhhhhothermoreeand_even_moreddddddddddddddddddddd
-    ) in eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffggggggggggggggggggggghhhhhhhhhhhhhhothermoreeand_even_moreddddddddddddddddddddd
     if fffffffffffffffffffffffffffffffffffffffffff
     < gggggggggggggggggggggggggggggggggggggggggggggg
     < hhhhhhhhhhhhhhhhhhhhhhhhhh

crates/ruff_python_formatter/tests/snapshots/format@expression__set_comp.py.snap

@@ -92,14 +92,16 @@ input_file: crates/ruff_python_formatter/resources/test/fixtures/ruff/expression
     aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
     + bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
     + [dddddddddddddddddd, eeeeeeeeeeeeeeeeeee]
-    for (
+    for ccccccccccccccccccccccccccccccccccccccc, ddddddddddddddddddd, [
-        ccccccccccccccccccccccccccccccccccccccc,
+        eeeeeeeeeeeeeeeeeeeeee,
-        ddddddddddddddddddd,
+        fffffffffffffffffffffffff,
-        [eeeeeeeeeeeeeeeeeeeeee, fffffffffffffffffffffffff],
+    ] in eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffggggggggggggggggggggghhhhhhhhhhhhhhothermoreeand_even_moreddddddddddddddddddddd
-    ) in eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeffffffffffffffffffffffffggggggggggggggggggggghhhhhhhhhhhhhhothermoreeand_even_moreddddddddddddddddddddd
     if fffffffffffffffffffffffffffffffffffffffffff
     < gggggggggggggggggggggggggggggggggggggggggggggg
     < hhhhhhhhhhhhhhhhhhhhhhhhhh
     if gggggggggggggggggggggggggggggggggggggggggggg
 }
 ```
+
+
+