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fix(source-type): don't treat d.ts as a declaration file #19185

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Merged
Dunqing merged 1 commit into from
Feb 10, 2026
Merged

fix(source-type): don't treat d.ts as a declaration file #19185

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21 changes: 14 additions & 7 deletions crates/oxc_span/src/source_type.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -152,18 +152,19 @@ impl FileExtension {
/// - `index.mts` -> false
/// - `index.d.css.ts` -> true
/// - `index.d.css.mts` -> false
/// - `d.ts` -> false
/// - `d.d.ts` -> true
/// - `d.css.mts` -> false
pub fn is_ts_declaration(self, file_name: &str) -> bool {
match self {
// https://www.typescriptlang.org/tsconfig/#allowArbitraryExtensions
// `{file basename}.d.{extension}.ts`
// https://github.com/microsoft/TypeScript/issues/50133
FileExtension::Ts => {
file_name[..file_name.len() - 3].split('.').rev().take(2).any(|c| c == "d")
}
FileExtension::Mts | FileExtension::Cts =>
{
#[expect(clippy::case_sensitive_file_extension_comparisons)]
file_name[..file_name.len() - 4].ends_with(".d")
FileExtension::Ts => file_name.rfind(".d.").is_some_and(|i| i != 0),
#[expect(clippy::case_sensitive_file_extension_comparisons)]
FileExtension::Mts | FileExtension::Cts => {
let base_file_name = &file_name[..file_name.len() - 4];
base_file_name.len() > 2 && base_file_name.ends_with(".d")
}
_ => false,
}
Expand Down Expand Up @@ -802,10 +803,16 @@ mod file_extension_tests {
let cases = vec![
("index.d.ts", true),
("index.ts", false),
("d.ts", false),
(".d.ts", false),
("index.d.mts", true),
("index.mts", false),
("d.mts", false),
(".d.mts", false),
("index.d.cts", true),
("index.cts", false),
("d.cts", false),
(".d.cts", false),
("index.d.js", false),
("index.js", false),
("index.d.jsx", false),
Expand Down
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