fix(es/codegen): Fix codegen of type-only imports (#8070)

crates/swc_ecma_codegen/src/lib.rs

@@ -240,6 +240,12 @@ where
         srcmap!(n, true);
 
         keyword!("import");
+
+        if n.type_only {
+            space!();
+            keyword!("type");
+        }
+
         let starts_with_ident = !n.specifiers.is_empty()
             && match &n.specifiers[0] {
                 ImportSpecifier::Default(_) => true,
@@ -328,6 +334,11 @@ where
     fn emit_import_specific(&mut self, node: &ImportNamedSpecifier) -> Result {
         srcmap!(node, true);
 
+        if node.is_type_only {
+            keyword!("type");
+            space!();
+        }
+
         if let Some(ref imported) = node.imported {
             emit!(imported);
             space!();

crates/swc_ecma_codegen/src/tests.rs

@@ -892,6 +892,57 @@ export default {
     );
 }
 
+#[test]
+fn emit_type_import_statement_named() {
+    let from = r#"
+      import type { X } from "y";
+    "#;
+    let to = r#"
+      import type { X } from "y";
+    "#;
+
+    let out = parse_then_emit(
+        from,
+        Default::default(),
+        Syntax::Typescript(Default::default()),
+    );
+    assert_eq!(DebugUsingDisplay(out.trim()), DebugUsingDisplay(to.trim()),);
+}
+
+#[test]
+fn emit_type_import_statement_default() {
+    let from = r#"
+      import type X from "y";
+    "#;
+    let to = r#"
+      import type X from "y";
+    "#;
+
+    let out = parse_then_emit(
+        from,
+        Default::default(),
+        Syntax::Typescript(Default::default()),
+    );
+    assert_eq!(DebugUsingDisplay(out.trim()), DebugUsingDisplay(to.trim()),);
+}
+
+#[test]
+fn emit_type_import_specifier() {
+    let from = r#"
+      import { type X } from "y";
+    "#;
+    let to = r#"
+      import { type X } from "y";
+    "#;
+
+    let out = parse_then_emit(
+        from,
+        Default::default(),
+        Syntax::Typescript(Default::default()),
+    );
+    assert_eq!(DebugUsingDisplay(out.trim()), DebugUsingDisplay(to.trim()),);
+}
+
 #[testing::fixture("tests/str-lits/**/*.txt")]
 fn test_str_lit(input: PathBuf) {
     test_str_lit_inner(input)

crates/swc_ecma_transforms_base/tests/ts-resolver/deno/lint/705/output.ts

@@ -1,4 +1,4 @@
-import { Foo__2 } from "./foo.ts";
+import type { Foo__2 } from "./foo.ts";
 function _bar__2(...Foo__3: Foo__2) {
     console.log(Foo__3);
 }

crates/swc_ecma_transforms_base/tests/ts-resolver/issues/6533/output.ts

@@ -1,5 +1,5 @@
 import * as F__2 from "foo";
-import { Thing__2 } from "anywhere";
+import type { Thing__2 } from "anywhere";
 console.log(F__2);
 export const inner__2 = <F__3>(a__3: F__3)=>{
     console.log(F__2);