fix(transformer/typescript): rewrite extensions in dynamic import() expressions

crates/oxc_transformer/src/lib.rs

@@ -704,6 +704,16 @@ impl<'a> Traverse<'a, TransformState<'a>> for TransformerImpl<'a> {
         }
     }
 
+    fn enter_import_expression(
+        &mut self,
+        node: &mut ImportExpression<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) {
+        if let Some(typescript) = self.x0_typescript.as_mut() {
+            typescript.enter_import_expression(node, ctx);
+        }
+    }
+
     fn enter_export_all_declaration(
         &mut self,
         node: &mut ExportAllDeclaration<'a>,

crates/oxc_transformer/src/typescript/mod.rs

@@ -313,6 +313,16 @@ impl<'a> Traverse<'a, TransformState<'a>> for TypeScript<'a> {
         }
     }
 
+    fn enter_import_expression(
+        &mut self,
+        node: &mut ImportExpression<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) {
+        if let Some(rewrite_extensions) = &mut self.rewrite_extensions {
+            rewrite_extensions.enter_import_expression(node, ctx);
+        }
+    }
+
     fn enter_formal_parameter_rest(
         &mut self,
         node: &mut FormalParameterRest<'a>,

crates/oxc_transformer/src/typescript/rewrite_extensions.rs

@@ -6,7 +6,8 @@
 //! Based on Babel's [plugin-rewrite-ts-imports](https://github.com/babel/babel/blob/3bcfee232506a4cebe410f02042fb0f0adeeb0b1/packages/babel-preset-typescript/src/plugin-rewrite-ts-imports.ts)
 
 use oxc_ast::ast::{
-    ExportAllDeclaration, ExportNamedDeclaration, ImportDeclaration, StringLiteral,
+    ExportAllDeclaration, ExportNamedDeclaration, Expression, ImportDeclaration, ImportExpression,
+    StringLiteral, TemplateLiteral,
 };
 use oxc_span::Atom;
 use oxc_traverse::Traverse;
@@ -19,32 +20,62 @@ pub struct TypeScriptRewriteExtensions {
     mode: RewriteExtensionsMode,
 }
 
+/// Given a specifier value, compute the replacement atom if the extension
+/// should be rewritten/removed. Returns `None` when no rewriting is needed.
+fn rewritten_specifier<'a>(
+    value: &'a str,
+    mode: RewriteExtensionsMode,
+    ctx: &TraverseCtx<'a>,
+) -> Option<Atom<'a>> {
+    if !value.contains(['/', '\\']) {
+        return None;
+    }
+
+    let (without_extension, extension) = value.rsplit_once('.')?;
+
+    let replace = match extension {
+        "mts" => ".mjs",
+        "cts" => ".cjs",
+        "ts" | "tsx" => ".js",
+        _ => return None,
+    };
+
+    Some(if mode.is_remove() {
+        Atom::from(without_extension)
+    } else {
+        ctx.ast.atom_from_strs_array([without_extension, replace])
+    })
+}
+
 impl TypeScriptRewriteExtensions {
     pub fn new(options: &TypeScriptOptions) -> Option<Self> {
         options.rewrite_import_extensions.map(|mode| Self { mode })
     }
 
     pub fn rewrite_extensions<'a>(&self, source: &mut StringLiteral<'a>, ctx: &TraverseCtx<'a>) {
-        let value = source.value.as_str();
-        if !value.contains(['/', '\\']) {
-            return;
+        if let Some(rewritten) = rewritten_specifier(source.value.as_str(), self.mode, ctx) {
+            source.value = rewritten;
+            source.raw = None;
         }
+    }
 
-        let Some((without_extension, extension)) = value.rsplit_once('.') else { return };
-
-        let replace = match extension {
-            "mts" => ".mjs",
-            "cts" => ".cjs",
-            "ts" | "tsx" => ".js",
-            _ => return, // do not rewrite or remove other unknown extensions
-        };
-
-        source.value = if self.mode.is_remove() {
-            Atom::from(without_extension)
-        } else {
-            ctx.ast.atom_from_strs_array([without_extension, replace])
-        };
-        source.raw = None;
+    fn rewrite_template_literal<'a>(
+        &self,
+        template: &mut TemplateLiteral<'a>,
+        ctx: &TraverseCtx<'a>,
+    ) {
+        if !template.is_no_substitution_template() {
+            return;
+        }
+        let quasi = &mut template.quasis[0];
+        // Read the specifier value from raw (always present).
+        // For no-substitution templates, raw and cooked are identical
+        // unless the template contains escape sequences, which import
+        // specifiers never do.
+        if let Some(rewritten) = rewritten_specifier(quasi.value.raw.as_str(), self.mode, ctx) {
+            quasi.value.raw = rewritten;
+            quasi.value.cooked = Some(rewritten);
+        }
     }
 }
 
@@ -83,4 +114,20 @@ impl<'a> Traverse<'a, TransformState<'a>> for TypeScriptRewriteExtensions {
         }
         self.rewrite_extensions(&mut node.source, ctx);
     }
+
+    fn enter_import_expression(
+        &mut self,
+        node: &mut ImportExpression<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) {
+        match &mut node.source {
+            Expression::StringLiteral(source) => {
+                self.rewrite_extensions(source, ctx);
+            }
+            Expression::TemplateLiteral(template) => {
+                self.rewrite_template_literal(template, ctx);
+            }
+            _ => {}
+        }
+    }
 }

tasks/transform_conformance/snapshots/oxc.snap.md

@@ -1,6 +1,6 @@
 commit: de54b9b2
 
-Passed: 203/334
+Passed: 204/335
 
 # All Passed:
 * babel-plugin-transform-class-static-block

tasks/transform_conformance/tests/babel-preset-typescript/test/fixtures/removeImportExtensions/input.ts

@@ -9,3 +9,15 @@ import "a-package/file.ts";
 // Bare import, it's either a node package or remapped by an import map
 import "soundcloud.ts";
 import "ipaddr.js";
+// Dynamic imports should also be rewritten.
+import("./a.ts");
+import("./a.mts");
+import("./a.cts");
+import("./react.tsx");
+import("a-package/file.ts");
+// Bare dynamic import should not be rewritten.
+import("soundcloud.ts");
+// No-substitution template literal should also be rewritten.
+import(`./a.ts`);
+// Non-string-literal dynamic import should not be rewritten.
+import(dynamicPath);

tasks/transform_conformance/tests/babel-preset-typescript/test/fixtures/removeImportExtensions/output.js

@@ -9,3 +9,15 @@ import "a-package/file";
 // Bare import, it's either a node package or remapped by an import map
 import "soundcloud.ts";
 import "ipaddr.js";
+// Dynamic imports should also be rewritten.
+import("./a");
+import("./a");
+import("./a");
+import("./react");
+import("a-package/file");
+// Bare dynamic import should not be rewritten.
+import("soundcloud.ts");
+// No-substitution template literal should also be rewritten.
+import(`./a`);
+// Non-string-literal dynamic import should not be rewritten.
+import(dynamicPath);

tasks/transform_conformance/tests/babel-preset-typescript/test/fixtures/rewriteImportExtensions/input.ts

@@ -0,0 +1,23 @@
+import "./a.ts";
+import "./a.mts";
+import "./a.cts";
+import "./react.tsx";
+// .mtsx and .ctsx are not valid and should not be transformed.
+import "./react.mtsx";
+import "./react.ctsx";
+import "a-package/file.ts";
+// Bare import, it's either a node package or remapped by an import map
+import "soundcloud.ts";
+import "ipaddr.js";
+// Dynamic imports should also be rewritten.
+import("./a.ts");
+import("./a.mts");
+import("./a.cts");
+import("./react.tsx");
+import("a-package/file.ts");
+// Bare dynamic import should not be rewritten.
+import("soundcloud.ts");
+// No-substitution template literal should also be rewritten.
+import(`./a.ts`);
+// Non-string-literal dynamic import should not be rewritten.
+import(dynamicPath);

tasks/transform_conformance/tests/babel-preset-typescript/test/fixtures/rewriteImportExtensions/options.json

@@ -0,0 +1,4 @@
+{
+  "sourceType": "module",
+  "presets": [["typescript", { "rewriteImportExtensions": "rewrite" }]]
+}

tasks/transform_conformance/tests/babel-preset-typescript/test/fixtures/rewriteImportExtensions/output.js

@@ -0,0 +1,23 @@
+import "./a.js";
+import "./a.mjs";
+import "./a.cjs";
+import "./react.js";
+// .mtsx and .ctsx are not valid and should not be transformed.
+import "./react.mtsx";
+import "./react.ctsx";
+import "a-package/file.js";
+// Bare import, it's either a node package or remapped by an import map
+import "soundcloud.ts";
+import "ipaddr.js";
+// Dynamic imports should also be rewritten.
+import("./a.js");
+import("./a.mjs");
+import("./a.cjs");
+import("./react.js");
+import("a-package/file.js");
+// Bare dynamic import should not be rewritten.
+import("soundcloud.ts");
+// No-substitution template literal should also be rewritten.
+import(`./a.js`);
+// Non-string-literal dynamic import should not be rewritten.
+import(dynamicPath);