Fix type-only import declaration with empty named imports being parsed as having a default import specifier (#817)

Co-authored-by: 강동윤 <kdy1997.dev@gmail.com>

ecmascript/parser/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "swc_ecma_parser"
-version = "0.24.2"
+version = "0.24.3"
 authors = ["강동윤 <kdy1997.dev@gmail.com>"]
 license = "Apache-2.0/MIT"
 repository = "https://github.com/swc-project/swc.git"

ecmascript/parser/src/parser/stmt/module_item.rs

@@ -60,8 +60,13 @@ impl<'a, I: Tokens> Parser<'a, I> {
             .map(ModuleItem::from);
         }
 
-        let type_only_span = self.input.cur_span();
-        let type_only = self.syntax().typescript() && eat!("type");
+        let type_only = self.input.syntax().typescript()
+            && is!("type")
+            && (peeked_is!('{') || !peeked_is!("from") && !peeked_is!(','));
+
+        if type_only {
+            assert_and_bump!("type");
+        }
 
         let mut specifiers = vec![];
 
@@ -101,14 +106,6 @@ impl<'a, I: Tokens> Parser<'a, I> {
             }
         }
 
-        // import type from './a';
-        if type_only && specifiers.is_empty() {
-            specifiers.push(ImportSpecifier::Default(ImportDefaultSpecifier {
-                span: span!(start),
-                local: Ident::new(js_word!("type"), type_only_span),
-            }));
-        }
-
         let src = self.parse_from_clause_and_semi()?;
 
         Ok(ModuleDecl::Import(ImportDecl {

ecmascript/parser/tests/typescript/custom/type-only/import/default/input.ts

@@ -1 +1,2 @@
 import type Foo from 'foo';
+import type from './a';

ecmascript/parser/tests/typescript/custom/type-only/import/default/input.ts.json

@@ -2,7 +2,7 @@
   "type": "Module",
   "span": {
     "start": 0,
-    "end": 27,
+    "end": 51,
     "ctxt": 0
   },
   "body": [
@@ -45,6 +45,46 @@
         "hasEscape": false
       },
       "typeOnly": true
+    },
+    {
+      "type": "ImportDeclaration",
+      "span": {
+        "start": 28,
+        "end": 51,
+        "ctxt": 0
+      },
+      "specifiers": [
+        {
+          "type": "ImportDefaultSpecifier",
+          "span": {
+            "start": 35,
+            "end": 39,
+            "ctxt": 0
+          },
+          "local": {
+            "type": "Identifier",
+            "span": {
+              "start": 35,
+              "end": 39,
+              "ctxt": 0
+            },
+            "value": "type",
+            "typeAnnotation": null,
+            "optional": false
+          }
+        }
+      ],
+      "source": {
+        "type": "StringLiteral",
+        "span": {
+          "start": 45,
+          "end": 50,
+          "ctxt": 0
+        },
+        "value": "./a",
+        "hasEscape": false
+      },
+      "typeOnly": false
     }
   ],
   "interpreter": null

ecmascript/parser/tests/typescript/custom/type-only/import/specific/input.ts

@@ -1 +1,2 @@
 import type { Foo } from 'foo';
+import type {} from 'foo';

ecmascript/parser/tests/typescript/custom/type-only/import/specific/input.ts.json

@@ -2,7 +2,7 @@
   "type": "Module",
   "span": {
     "start": 0,
-    "end": 31,
+    "end": 58,
     "ctxt": 0
   },
   "body": [
@@ -46,6 +46,26 @@
         "hasEscape": false
       },
       "typeOnly": true
+    },
+    {
+      "type": "ImportDeclaration",
+      "span": {
+        "start": 32,
+        "end": 58,
+        "ctxt": 0
+      },
+      "specifiers": [],
+      "source": {
+        "type": "StringLiteral",
+        "span": {
+          "start": 52,
+          "end": 57,
+          "ctxt": 0
+        },
+        "value": "foo",
+        "hasEscape": false
+      },
+      "typeOnly": true
     }
   ],
   "interpreter": null