Accept empty inner calls in C414 (#6725)

Closes #6716.

crates/ruff/resources/test/fixtures/flake8_comprehensions/C414.py

@@ -22,6 +22,10 @@
         "o"]
     )
 )
+set(set())
+set(list())
+set(tuple())
+sorted(reversed())
 
 # Nested sorts with differing keyword arguments. Not flagged.
 sorted(sorted(x, key=lambda y: y))

crates/ruff/src/rules/flake8_comprehensions/fixes.rs

@@ -765,13 +765,14 @@ pub(crate) fn fix_unnecessary_double_cast_or_process(
     outer_call.args = match outer_call.args.split_first() {
         Some((first, rest)) => {
             let inner_call = match_call(&first.value)?;
-            if let Some(iterable) = inner_call.args.first() {
-                let mut args = vec![iterable.clone()];
-                args.extend_from_slice(rest);
-                args
-            } else {
-                bail!("Expected at least one argument in inner function call");
-            }
+            inner_call
+                .args
+                .iter()
+                .filter(|argument| argument.keyword.is_none())
+                .take(1)
+                .chain(rest.iter())
+                .cloned()
+                .collect::<Vec<_>>()
         }
         None => bail!("Expected at least one argument in outer function call"),
     };

crates/ruff/src/rules/flake8_comprehensions/snapshots/ruff__rules__flake8_comprehensions__tests__C414_C414.py.snap

@@ -365,8 +365,8 @@ C414.py:19:1: C414 [*] Unnecessary `list` call within `tuple()`
 23 | |     )
 24 | | )
    | |_^ C414
-25 |   
-26 |   # Nested sorts with differing keyword arguments. Not flagged.
+25 |   set(set())
+26 |   set(list())
    |
    = help: Remove the inner `list` call
 
@@ -380,8 +380,91 @@ C414.py:19:1: C414 [*] Unnecessary `list` call within `tuple()`
 22 21 |         "o"]
 23 22 |     )
 24    |-)
-25 23 | 
-26 24 | # Nested sorts with differing keyword arguments. Not flagged.
-27 25 | sorted(sorted(x, key=lambda y: y))
+25 23 | set(set())
+26 24 | set(list())
+27 25 | set(tuple())
+
+C414.py:25:1: C414 [*] Unnecessary `set` call within `set()`
+   |
+23 |     )
+24 | )
+25 | set(set())
+   | ^^^^^^^^^^ C414
+26 | set(list())
+27 | set(tuple())
+   |
+   = help: Remove the inner `set` call
+
+ℹ Suggested fix
+22 22 |         "o"]
+23 23 |     )
+24 24 | )
+25    |-set(set())
+   25 |+set()
+26 26 | set(list())
+27 27 | set(tuple())
+28 28 | sorted(reversed())
+
+C414.py:26:1: C414 [*] Unnecessary `list` call within `set()`
+   |
+24 | )
+25 | set(set())
+26 | set(list())
+   | ^^^^^^^^^^^ C414
+27 | set(tuple())
+28 | sorted(reversed())
+   |
+   = help: Remove the inner `list` call
+
+ℹ Suggested fix
+23 23 |     )
+24 24 | )
+25 25 | set(set())
+26    |-set(list())
+   26 |+set()
+27 27 | set(tuple())
+28 28 | sorted(reversed())
+29 29 | 
+
+C414.py:27:1: C414 [*] Unnecessary `tuple` call within `set()`
+   |
+25 | set(set())
+26 | set(list())
+27 | set(tuple())
+   | ^^^^^^^^^^^^ C414
+28 | sorted(reversed())
+   |
+   = help: Remove the inner `tuple` call
+
+ℹ Suggested fix
+24 24 | )
+25 25 | set(set())
+26 26 | set(list())
+27    |-set(tuple())
+   27 |+set()
+28 28 | sorted(reversed())
+29 29 | 
+30 30 | # Nested sorts with differing keyword arguments. Not flagged.
+
+C414.py:28:1: C414 [*] Unnecessary `reversed` call within `sorted()`
+   |
+26 | set(list())
+27 | set(tuple())
+28 | sorted(reversed())
+   | ^^^^^^^^^^^^^^^^^^ C414
+29 | 
+30 | # Nested sorts with differing keyword arguments. Not flagged.
+   |
+   = help: Remove the inner `reversed` call
+
+ℹ Suggested fix
+25 25 | set(set())
+26 26 | set(list())
+27 27 | set(tuple())
+28    |-sorted(reversed())
+   28 |+sorted()
+29 29 | 
+30 30 | # Nested sorts with differing keyword arguments. Not flagged.
+31 31 | sorted(sorted(x, key=lambda y: y))