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fix(unicorn/prefer-string-slice): avoid unsafe autofix for substr-to-slice #20010

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Merged
graphite-app merged 1 commit into from
Mar 5, 2026
Merged

fix(unicorn/prefer-string-slice): avoid unsafe autofix for substr-to-slice #20010

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56 changes: 51 additions & 5 deletions crates/oxc_linter/src/rules/unicorn/prefer_string_slice.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,7 @@
use oxc_ast::{AstKind, ast::MemberExpression};
use oxc_ast::{
AstKind,
ast::{Argument, Expression, MemberExpression},
};
use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_span::Span;
Expand Down Expand Up @@ -36,7 +39,7 @@ declare_oxc_lint!(
PreferStringSlice,
unicorn,
pedantic,
fix
conditional_fix
);

impl Rule for PreferStringSlice {
Expand All @@ -53,14 +56,58 @@ impl Rule for PreferStringSlice {
if !matches!(v.property.name.as_str(), "substr" | "substring") {
return;
}
let method_name = v.property.name.as_str();
let has_spread_arguments = call_expr.arguments.iter().any(Argument::is_spread);
let has_unsafe_arguments = match method_name {
"substr" => has_spread_arguments || call_expr.arguments.len() >= 2,
"substring" => {
has_spread_arguments || !is_safe_substring_arguments(&call_expr.arguments)
}
_ => unreachable!(),
};

if has_unsafe_arguments {
ctx.diagnostic(prefer_string_slice_diagnostic(v.property.span, method_name));
return;
}

ctx.diagnostic_with_fix(
prefer_string_slice_diagnostic(v.property.span, v.property.name.as_str()),
prefer_string_slice_diagnostic(v.property.span, method_name),
|fixer| fixer.replace(v.property.span, "slice"),
);
}
}
}

fn is_safe_substring_arguments(arguments: &[Argument<'_>]) -> bool {
match arguments {
[] => true,
[start] => get_non_negative_integer_argument(start).is_some(),
[start, end] => {
let Some(start_value) = get_non_negative_integer_argument(start) else {
return false;
};
let Some(end_value) = get_non_negative_integer_argument(end) else {
return false;
};
start_value <= end_value
}
_ => false,
}
}

fn get_non_negative_integer_argument(argument: &Argument<'_>) -> Option<f64> {
if !argument.is_expression() {
return None;
}

let Expression::NumericLiteral(number) = argument.to_expression().get_inner_expression() else {
return None;
};

if number.value >= 0.0 && number.value.fract() == 0.0 { Some(number.value) } else { None }
}

#[test]
fn test() {
use crate::tester::Tester;
Expand Down Expand Up @@ -90,6 +137,7 @@ fn test() {
r#""foo".substr()"#,
r#""foo".substr(1)"#,
r#""foo".substr(1, 2)"#,
r#""foo".substr(11, 8)"#,
r#""foo".substr(bar.length, Math.min(baz, 100))"#,
r#""foo".substr(1, length)"#,
r#""foo".substr(1, "abc".length)"#,
Expand Down Expand Up @@ -168,7 +216,6 @@ fn test() {
// "foo".slice(0, Math.max(0, length))"#,
// ),
// (r#""foo".substr(0, -1)"#, r#""foo".slice(0, 0)"#),
(r#""foo".substr(0, "foo".length)"#, r#""foo".slice(0, "foo".length)"#),
(
"const uri = 'foo';
((uri || '')).substr(1)",
Expand All @@ -192,7 +239,6 @@ fn test() {
// (r#""foo".substring(-1, -5)"#, r#""foo".slice(0, 0)"#),
// (r#""foo".substring(-1, 2)"#, r#""foo".slice(0, 2)"#),
// (r#""foo".substring(length)"#, r#""foo".slice(Math.max(0, length))"#),
(r#""foo".substring("fo".length)"#, r#""foo".slice("fo".length)"#), // spellchecker:disable-line
// TODO: Get this passing.
// (r#""foo".substring(0, length)"#, r#""foo".slice(0, Math.max(0, length))"#),
// (r#""foo".substring(length, 0)"#, r#""foo".slice(0, Math.max(0, length))"#),
Expand Down
40 changes: 6 additions & 34 deletions crates/oxc_linter/src/snapshots/unicorn_prefer_string_slice.snap
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -84,64 +84,61 @@ source: crates/oxc_linter/src/tester.rs
1 │ "foo".substr(1, 2)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(11, 8)
· ──────
╰────

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(bar.length, Math.min(baz, 100))
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(1, length)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(1, "abc".length)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr("1", 2)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(0, -1)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(0, "foo".length)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:2:19]
1 │ const length = 123;
2 │ "foo".substr(1, length - 4)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(1, length)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:2:27]
Expand Down Expand Up @@ -170,28 +167,24 @@ source: crates/oxc_linter/src/tester.rs
1 │ foo.substr(start, length)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substr(1, 2)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substr(1, 2, 3)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:10]
1 │ "Sample".substr(0, "Sample".lastIndexOf("/"))
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:5]
Expand Down Expand Up @@ -226,56 +219,48 @@ source: crates/oxc_linter/src/tester.rs
1 │ "foo".substring(2, 1)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substring(-1, -5)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substring(-1, 2)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substring(length)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:10]
1 │ "foobar".substring("foo".length)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substring(0, length)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
1 │ "foo".substring(length, 0)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substring(start)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
Expand All @@ -289,7 +274,6 @@ source: crates/oxc_linter/src/tester.rs
1 │ foo.substring(start, end)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:7]
Expand All @@ -303,7 +287,6 @@ source: crates/oxc_linter/src/tester.rs
1 │ foo.substring(1, 2, 3)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:2:40]
Expand All @@ -330,75 +313,64 @@ source: crates/oxc_linter/src/tester.rs
· ─────────
3 │ /* 9 */ (( /* 10 */ bar /* 11 */ )) /* 12 */,
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substr(0, ...bar)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substr(...bar)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substr(0, (100, 1))
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substr(0, 1, extraArgument)
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substr((0, bar.length), (0, baz.length))
· ──────
╰────
help: Replace `substr` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substring((10, 1), 0)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substring(0, (10, 1))
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substring(0, await 1)
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substring()
╭─[prefer_string_slice.tsx:1:5]
1 │ foo.substring((10, bar))
· ─────────
╰────
help: Replace `substring` with `slice`.

⚠ eslint-plugin-unicorn(prefer-string-slice): Prefer String#slice() over String#substr()
╭─[prefer_string_slice.tsx:2:35]
1 │ const string = "::";
2 │ const output = string.substr(-2, 2);
· ──────
╰────
help: Replace `substr` with `slice`.
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