Apply RUF017 when start is passed via position (#6664)

As discussed in #6489 (comment). Linking #5073
astral-sh · Aug 18, 2023 · a128fe5 · a128fe5
1 parent 5892c69
commit a128fe5
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diff --git a/crates/ruff/src/rules/ruff/rules/quadratic_list_summation.rs b/crates/ruff/src/rules/ruff/rules/quadratic_list_summation.rs
@@ -119,11 +119,11 @@ fn func_is_builtin(func: &Expr, name: &str, semantic: &SemanticModel) -> bool {
 
 /// Returns `true` if the `start` argument to a `sum()` call is an empty list.
 fn start_is_empty_list(arguments: &Arguments, semantic: &SemanticModel) -> bool {
-    let Some(keyword) = arguments.find_keyword("start") else {
+    let Some(start_arg) = arguments.find_argument("start", 1) else {
         return false;
     };
 
-    match &keyword.value {
+    match start_arg {
         Expr::Call(ast::ExprCall {
             func, arguments, ..
         }) => arguments.is_empty() && func_is_builtin(func, "list", semantic),

diff --git a/crates/ruff/src/rules/ruff/snapshots/ruff__rules__ruff__tests__RUF017_RUF017.py.snap b/crates/ruff/src/rules/ruff/snapshots/ruff__rules__ruff__tests__RUF017_RUF017.py.snap
@@ -24,6 +24,31 @@ RUF017.py:5:1: RUF017 [*] Avoid quadratic list summation
 7 9 | sum([[1, 2, 3], [4, 5, 6]], start=[])
 8 10 | sum([[1, 2, 3], [4, 5, 6]], [])
 
+RUF017.py:6:1: RUF017 [*] Avoid quadratic list summation
+  |
+4 | # RUF017
+5 | sum([x, y], start=[])
+6 | sum([x, y], [])
+  | ^^^^^^^^^^^^^^^ RUF017
+7 | sum([[1, 2, 3], [4, 5, 6]], start=[])
+8 | sum([[1, 2, 3], [4, 5, 6]], [])
+  |
+  = help: Replace with `functools.reduce`
+
+ℹ Suggested fix
+  1 |+import functools
+  2 |+import operator
+1 3 | x = [1, 2, 3]
+2 4 | y = [4, 5, 6]
+3 5 | 
+4 6 | # RUF017
+5 7 | sum([x, y], start=[])
+6   |-sum([x, y], [])
+  8 |+functools.reduce(operator.iadd, [x, y], [])
+7 9 | sum([[1, 2, 3], [4, 5, 6]], start=[])
+8 10 | sum([[1, 2, 3], [4, 5, 6]], [])
+9 11 | sum([[1, 2, 3], [4, 5, 6]],
+
 RUF017.py:7:1: RUF017 [*] Avoid quadratic list summation
   |
 5 | sum([x, y], start=[])
@@ -50,4 +75,60 @@ RUF017.py:7:1: RUF017 [*] Avoid quadratic list summation
 9  11 | sum([[1, 2, 3], [4, 5, 6]],
 10 12 |     [])
 
+RUF017.py:8:1: RUF017 [*] Avoid quadratic list summation
+   |
+ 6 | sum([x, y], [])
+ 7 | sum([[1, 2, 3], [4, 5, 6]], start=[])
+ 8 | sum([[1, 2, 3], [4, 5, 6]], [])
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ RUF017
+ 9 | sum([[1, 2, 3], [4, 5, 6]],
+10 |     [])
+   |
+   = help: Replace with `functools.reduce`
+
+ℹ Suggested fix
+   1  |+import functools
+   2  |+import operator
+1  3  | x = [1, 2, 3]
+2  4  | y = [4, 5, 6]
+3  5  | 
+--------------------------------------------------------------------------------
+5  7  | sum([x, y], start=[])
+6  8  | sum([x, y], [])
+7  9  | sum([[1, 2, 3], [4, 5, 6]], start=[])
+8     |-sum([[1, 2, 3], [4, 5, 6]], [])
+   10 |+functools.reduce(operator.iadd, [[1, 2, 3], [4, 5, 6]], [])
+9  11 | sum([[1, 2, 3], [4, 5, 6]],
+10 12 |     [])
+11 13 | 
+
+RUF017.py:9:1: RUF017 [*] Avoid quadratic list summation
+   |
+ 7 |   sum([[1, 2, 3], [4, 5, 6]], start=[])
+ 8 |   sum([[1, 2, 3], [4, 5, 6]], [])
+ 9 | / sum([[1, 2, 3], [4, 5, 6]],
+10 | |     [])
+   | |_______^ RUF017
+11 |   
+12 |   # OK
+   |
+   = help: Replace with `functools.reduce`
+
+ℹ Suggested fix
+   1  |+import functools
+   2  |+import operator
+1  3  | x = [1, 2, 3]
+2  4  | y = [4, 5, 6]
+3  5  | 
+--------------------------------------------------------------------------------
+6  8  | sum([x, y], [])
+7  9  | sum([[1, 2, 3], [4, 5, 6]], start=[])
+8  10 | sum([[1, 2, 3], [4, 5, 6]], [])
+9     |-sum([[1, 2, 3], [4, 5, 6]],
+10    |-    [])
+   11 |+functools.reduce(operator.iadd, [[1, 2, 3], [4, 5, 6]], [])
+11 12 | 
+12 13 | # OK
+13 14 | sum([x, y])
+