fix(es/loader): Support fully-specified ESM import specifiers (#3050)

crates/swc_bundler/tests/common/mod.rs

@@ -167,10 +167,39 @@ impl NodeResolver {
             return Ok(path.to_path_buf());
         }
 
-        for ext in EXTENSIONS {
-            let ext_path = path.with_extension(ext);
-            if ext_path.is_file() {
-                return Ok(ext_path);
+        if let Some(name) = path.file_name() {
+            let mut ext_path = path.to_path_buf();
+            let name = name.to_string_lossy();
+            for ext in EXTENSIONS {
+                ext_path.set_file_name(format!("{}.{}", name, ext));
+                if ext_path.is_file() {
+                    return Ok(ext_path);
+                }
+            }
+
+            // TypeScript-specific behavior: if the extension is ".js" or ".jsx",
+            // try replacing it with ".ts" or ".tsx".
+            ext_path.set_file_name(name.into_owned());
+            let old_ext = path.extension().and_then(|ext| ext.to_str());
+
+            if let Some(old_ext) = old_ext {
+                let extensions = match old_ext {
+                    // Note that the official compiler code always tries ".ts" before
+                    // ".tsx" even if the original extension was ".jsx".
+                    "js" => ["ts", "tsx"].as_slice(),
+                    "jsx" => ["ts", "tsx"].as_slice(),
+                    "mjs" => ["mts"].as_slice(),
+                    "cjs" => ["cts"].as_slice(),
+                    _ => [].as_slice(),
+                };
+
+                for ext in extensions {
+                    ext_path.set_extension(ext);
+
+                    if ext_path.is_file() {
+                        return Ok(ext_path);
+                    }
+                }
             }
         }
 

crates/swc_bundler/tests/fixture/issue-3043/case1/input/entry.ts

@@ -0,0 +1,2 @@
+import { two } from "./two.js";
+two();

crates/swc_bundler/tests/fixture/issue-3043/case1/input/two.ts

@@ -0,0 +1 @@
+export function two() {}

crates/swc_bundler/tests/fixture/issue-3043/case1/output/entry.inlined.ts

@@ -0,0 +1,3 @@
+function two() {
+}
+two();

crates/swc_bundler/tests/fixture/issue-3043/case1/output/entry.ts

@@ -0,0 +1,3 @@
+function two() {
+}
+two();

crates/swc_bundler/tests/fixture/issue-3043/case2/input/entry.ts

@@ -0,0 +1,2 @@
+import { result } from "./foo.js";
+console.log(result);

crates/swc_bundler/tests/fixture/issue-3043/case2/input/foo.js.ts

@@ -0,0 +1 @@
+export const result = "foo.js.ts";

crates/swc_bundler/tests/fixture/issue-3043/case2/input/foo.ts

@@ -0,0 +1 @@
+export const result = "foo.ts";

crates/swc_bundler/tests/fixture/issue-3043/case2/output/entry.inlined.ts

@@ -0,0 +1,2 @@
+const result = "foo.js.ts";
+console.log(result);

crates/swc_bundler/tests/fixture/issue-3043/case2/output/entry.ts

@@ -0,0 +1,2 @@
+const result = "foo.js.ts";
+console.log(result);

crates/swc_bundler/tests/fixture/issue-3043/case3/input/entry.ts

@@ -0,0 +1,2 @@
+import { result } from "./foo.mjs";
+console.log(result);

crates/swc_bundler/tests/fixture/issue-3043/case3/input/foo.mts

@@ -0,0 +1 @@
+export const result = "foo.mts";

crates/swc_bundler/tests/fixture/issue-3043/case3/input/foo.ts

@@ -0,0 +1 @@
+export const result = "foo.ts";

crates/swc_bundler/tests/fixture/issue-3043/case3/output/entry.inlined.ts

@@ -0,0 +1,2 @@
+const result = "foo.mts";
+console.log(result);

crates/swc_bundler/tests/fixture/issue-3043/case3/output/entry.ts

@@ -0,0 +1,2 @@
+const result = "foo.mts";
+console.log(result);

crates/swc_ecma_loader/src/resolvers/node.rs

@@ -115,6 +115,31 @@ impl NodeModulesResolver {
                     return Ok(Some(ext_path));
                 }
             }
+
+            // TypeScript-specific behavior: if the extension is ".js" or ".jsx",
+            // try replacing it with ".ts" or ".tsx".
+            ext_path.set_file_name(name.into_owned());
+            let old_ext = path.extension().and_then(|ext| ext.to_str());
+
+            if let Some(old_ext) = old_ext {
+                let extensions = match old_ext {
+                    // Note that the official compiler code always tries ".ts" before
+                    // ".tsx" even if the original extension was ".jsx".
+                    "js" => ["ts", "tsx"].as_slice(),
+                    "jsx" => ["ts", "tsx"].as_slice(),
+                    "mjs" => ["mts"].as_slice(),
+                    "cjs" => ["cts"].as_slice(),
+                    _ => [].as_slice(),
+                };
+
+                for ext in extensions {
+                    ext_path.set_extension(ext);
+
+                    if ext_path.is_file() {
+                        return Ok(Some(ext_path));
+                    }
+                }
+            }
         }
 
         bail!("file not found: {}", path.display())