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[flake8-simplify] Implement fix for maxsplit without separator (SIM905) #19851

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Merged
ntBre merged 2 commits into from
Aug 15, 2025
Merged

[flake8-simplify] Implement fix for maxsplit without separator (SIM905) #19851

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f971443
Implement fix for maxsplit without separator
RazerM Aug 10, 2025
98aee79
Gate fix behind preview
RazerM Aug 14, 2025
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4 changes: 4 additions & 0 deletions crates/ruff_linter/resources/test/fixtures/flake8_simplify/SIM905.py
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Original file line number Diff line number Diff line change
Expand Up @@ -166,3 +166,7 @@
print("S\x1cP\x1dL\x1eI\x1fT".split())
print("\x1c\x1d\x1e\x1f>".split(maxsplit=0))
print("<\x1c\x1d\x1e\x1f".rsplit(maxsplit=0))

# leading/trailing whitespace should not count towards maxsplit
" a b c d ".split(maxsplit=2) # ["a", "b", "c d "]
" a b c d ".rsplit(maxsplit=2) # [" a b", "c", "d"]
26 changes: 22 additions & 4 deletions crates/ruff_linter/src/rules/flake8_simplify/rules/split_static_string.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -185,10 +185,28 @@ fn split_default(
let string_val = str_value.to_str();
match max_split.cmp(&0) {
Ordering::Greater => {
// Autofix for `maxsplit` without separator not yet implemented, as
// `split_whitespace().remainder()` is not stable:
// https://doc.rust-lang.org/std/str/struct.SplitWhitespace.html#method.remainder
None
let Ok(max_split) = usize::try_from(max_split) else {
return None;
};
let list_items: Vec<&str> = if direction == Direction::Left {
string_val
.trim_start_matches(py_unicode_is_whitespace)
.splitn(max_split + 1, py_unicode_is_whitespace)
.filter(|s| !s.is_empty())
.collect()
} else {
let mut items: Vec<&str> = string_val
.trim_end_matches(py_unicode_is_whitespace)
.rsplitn(max_split + 1, py_unicode_is_whitespace)
.filter(|s| !s.is_empty())
.collect();
items.reverse();
items
};
Some(construct_replacement(
&list_items,
str_value.first_literal_flags(),
))
}
Ordering::Equal => {
// Behavior for maxsplit = 0 when sep is None:
Expand Down
115 changes: 109 additions & 6 deletions ...ake8_simplify/snapshots/ruff_linter__rules__flake8_simplify__tests__SIM905_SIM905.py.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -95,7 +95,7 @@ help: Replace with list literal
16 16 | "a,b,c,d".split(sep=",")
17 17 | "a,b,c,d".split(sep=None)

SIM905 Consider using a list literal instead of `str.split`
SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:15:1
|
13 | "a,b,c,d".split(None)
Expand All @@ -107,6 +107,16 @@ SIM905 Consider using a list literal instead of `str.split`
|
help: Replace with list literal

ℹ Safe fix
12 12 | "a,b,c,d".split(",")
13 13 | "a,b,c,d".split(None)
14 14 | "a,b,c,d".split(",", 1)
15 |-"a,b,c,d".split(None, 1)
15 |+["a,b,c,d"]
16 16 | "a,b,c,d".split(sep=",")
17 17 | "a,b,c,d".split(sep=None)
18 18 | "a,b,c,d".split(sep=",", maxsplit=1)

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:16:1
|
Expand Down Expand Up @@ -173,7 +183,7 @@ help: Replace with list literal
20 20 | "a,b,c,d".split(maxsplit=1, sep=",")
21 21 | "a,b,c,d".split(maxsplit=1, sep=None)

SIM905 Consider using a list literal instead of `str.split`
SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:19:1
|
17 | "a,b,c,d".split(sep=None)
Expand All @@ -185,6 +195,16 @@ SIM905 Consider using a list literal instead of `str.split`
|
help: Replace with list literal

ℹ Safe fix
16 16 | "a,b,c,d".split(sep=",")
17 17 | "a,b,c,d".split(sep=None)
18 18 | "a,b,c,d".split(sep=",", maxsplit=1)
19 |-"a,b,c,d".split(sep=None, maxsplit=1)
19 |+["a,b,c,d"]
20 20 | "a,b,c,d".split(maxsplit=1, sep=",")
21 21 | "a,b,c,d".split(maxsplit=1, sep=None)
22 22 | "a,b,c,d".split(",", maxsplit=1)

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:20:1
|
Expand All @@ -207,7 +227,7 @@ help: Replace with list literal
22 22 | "a,b,c,d".split(",", maxsplit=1)
23 23 | "a,b,c,d".split(None, maxsplit=1)

SIM905 Consider using a list literal instead of `str.split`
SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:21:1
|
19 | "a,b,c,d".split(sep=None, maxsplit=1)
Expand All @@ -219,6 +239,16 @@ SIM905 Consider using a list literal instead of `str.split`
|
help: Replace with list literal

ℹ Safe fix
18 18 | "a,b,c,d".split(sep=",", maxsplit=1)
19 19 | "a,b,c,d".split(sep=None, maxsplit=1)
20 20 | "a,b,c,d".split(maxsplit=1, sep=",")
21 |-"a,b,c,d".split(maxsplit=1, sep=None)
21 |+["a,b,c,d"]
22 22 | "a,b,c,d".split(",", maxsplit=1)
23 23 | "a,b,c,d".split(None, maxsplit=1)
24 24 | "a,b,c,d".split(maxsplit=1)

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:22:1
|
Expand All @@ -241,7 +271,7 @@ help: Replace with list literal
24 24 | "a,b,c,d".split(maxsplit=1)
25 25 | "a,b,c,d".split(maxsplit=1.0)

SIM905 Consider using a list literal instead of `str.split`
SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:23:1
|
21 | "a,b,c,d".split(maxsplit=1, sep=None)
Expand All @@ -253,7 +283,17 @@ SIM905 Consider using a list literal instead of `str.split`
|
help: Replace with list literal

SIM905 Consider using a list literal instead of `str.split`
ℹ Safe fix
20 20 | "a,b,c,d".split(maxsplit=1, sep=",")
21 21 | "a,b,c,d".split(maxsplit=1, sep=None)
22 22 | "a,b,c,d".split(",", maxsplit=1)
23 |-"a,b,c,d".split(None, maxsplit=1)
23 |+["a,b,c,d"]
24 24 | "a,b,c,d".split(maxsplit=1)
25 25 | "a,b,c,d".split(maxsplit=1.0)
26 26 | "a,b,c,d".split(maxsplit=1)

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:24:1
|
22 | "a,b,c,d".split(",", maxsplit=1)
Expand All @@ -265,7 +305,17 @@ SIM905 Consider using a list literal instead of `str.split`
|
help: Replace with list literal

SIM905 Consider using a list literal instead of `str.split`
ℹ Safe fix
21 21 | "a,b,c,d".split(maxsplit=1, sep=None)
22 22 | "a,b,c,d".split(",", maxsplit=1)
23 23 | "a,b,c,d".split(None, maxsplit=1)
24 |-"a,b,c,d".split(maxsplit=1)
24 |+["a,b,c,d"]
25 25 | "a,b,c,d".split(maxsplit=1.0)
26 26 | "a,b,c,d".split(maxsplit=1)
27 27 | "a,b,c,d".split(maxsplit=0)

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:26:1
|
24 | "a,b,c,d".split(maxsplit=1)
Expand All @@ -277,6 +327,16 @@ SIM905 Consider using a list literal instead of `str.split`
|
help: Replace with list literal

ℹ Safe fix
23 23 | "a,b,c,d".split(None, maxsplit=1)
24 24 | "a,b,c,d".split(maxsplit=1)
25 25 | "a,b,c,d".split(maxsplit=1.0)
26 |-"a,b,c,d".split(maxsplit=1)
26 |+["a,b,c,d"]
27 27 | "a,b,c,d".split(maxsplit=0)
28 28 | "VERB AUX PRON ADP DET".split(" ")
29 29 | ' 1 2 3 '.split()

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:27:1
|
Expand Down Expand Up @@ -1439,6 +1499,7 @@ help: Replace with list literal
166 |+print(["S", "P", "L", "I", "T"])
167 167 | print("\x1c\x1d\x1e\x1f>".split(maxsplit=0))
168 168 | print("<\x1c\x1d\x1e\x1f".rsplit(maxsplit=0))
169 169 |

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:167:7
Expand All @@ -1458,6 +1519,8 @@ help: Replace with list literal
167 |-print("\x1c\x1d\x1e\x1f>".split(maxsplit=0))
167 |+print([">"])
168 168 | print("<\x1c\x1d\x1e\x1f".rsplit(maxsplit=0))
169 169 |
170 170 | # leading/trailing whitespace should not count towards maxsplit

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:168:7
Expand All @@ -1466,6 +1529,8 @@ SIM905 [*] Consider using a list literal instead of `str.split`
167 | print("\x1c\x1d\x1e\x1f>".split(maxsplit=0))
168 | print("<\x1c\x1d\x1e\x1f".rsplit(maxsplit=0))
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
169 |
170 | # leading/trailing whitespace should not count towards maxsplit
|
help: Replace with list literal

Expand All @@ -1475,3 +1540,41 @@ help: Replace with list literal
167 167 | print("\x1c\x1d\x1e\x1f>".split(maxsplit=0))
168 |-print("<\x1c\x1d\x1e\x1f".rsplit(maxsplit=0))
168 |+print(["<"])
169 169 |
170 170 | # leading/trailing whitespace should not count towards maxsplit
171 171 | " a b c d ".split(maxsplit=2) # ["a", "b", "c d "]

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:171:1
|
170 | # leading/trailing whitespace should not count towards maxsplit
171 | " a b c d ".split(maxsplit=2) # ["a", "b", "c d "]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
172 | " a b c d ".rsplit(maxsplit=2) # [" a b", "c", "d"]
|
help: Replace with list literal

ℹ Safe fix
168 168 | print("<\x1c\x1d\x1e\x1f".rsplit(maxsplit=0))
169 169 |
170 170 | # leading/trailing whitespace should not count towards maxsplit
171 |-" a b c d ".split(maxsplit=2) # ["a", "b", "c d "]
171 |+["a", "b", "c d "] # ["a", "b", "c d "]
172 172 | " a b c d ".rsplit(maxsplit=2) # [" a b", "c", "d"]

SIM905 [*] Consider using a list literal instead of `str.split`
--> SIM905.py:172:1
|
170 | # leading/trailing whitespace should not count towards maxsplit
171 | " a b c d ".split(maxsplit=2) # ["a", "b", "c d "]
172 | " a b c d ".rsplit(maxsplit=2) # [" a b", "c", "d"]
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: Replace with list literal

ℹ Safe fix
169 169 |
170 170 | # leading/trailing whitespace should not count towards maxsplit
171 171 | " a b c d ".split(maxsplit=2) # ["a", "b", "c d "]
172 |-" a b c d ".rsplit(maxsplit=2) # [" a b", "c", "d"]
172 |+[" a b", "c", "d"] # [" a b", "c", "d"]