fix(es/typescript): Preserve const enum for named export (#8208)

**Related issue:**

- Closes: #8204

Author: magic-akari

crates/swc/tests/fixture/issues-8xxx/8204/input/index.ts

@@ -0,0 +1,2 @@
+const enum Bar { VALUE = 1 }
+export default Bar;

crates/swc/tests/fixture/issues-8xxx/8204/output/index.ts

@@ -0,0 +1,5 @@
+var Bar;
+(function(Bar) {
+    Bar[Bar["VALUE"] = 1] = "VALUE";
+})(Bar || (Bar = {}));
+export default Bar;

crates/swc/tests/tsc-references/enums.1.normal.js

@@ -5,6 +5,10 @@ var SyntaxKind;
     SyntaxKind[SyntaxKind["ExportDeclaration"] = 1] = "ExportDeclaration";
 })(SyntaxKind || (SyntaxKind = {}));
 var SymbolFlags;
+(function(SymbolFlags) {
+    SymbolFlags["Type"] = "Type";
+    SymbolFlags["Value"] = "Value";
+})(SymbolFlags || (SymbolFlags = {}));
 export { SymbolFlags };
 //// [/b.ts]
 SyntaxKind.ImportClause;

crates/swc/tests/tsc-references/enums.2.minified.js

@@ -1,6 +1,6 @@
 //// [/a.ts]
-var SyntaxKind, SymbolFlags, SyntaxKind1;
-(SyntaxKind1 = SyntaxKind || (SyntaxKind = {}))[SyntaxKind1.ImportClause = 0] = "ImportClause", SyntaxKind1[SyntaxKind1.ExportDeclaration = 1] = "ExportDeclaration";
+var SyntaxKind, SymbolFlags, SyntaxKind1, SymbolFlags1;
+(SyntaxKind1 = SyntaxKind || (SyntaxKind = {}))[SyntaxKind1.ImportClause = 0] = "ImportClause", SyntaxKind1[SyntaxKind1.ExportDeclaration = 1] = "ExportDeclaration", (SymbolFlags1 = SymbolFlags || (SymbolFlags = {})).Type = "Type", SymbolFlags1.Value = "Value";
 export { SymbolFlags };
 //// [/b.ts]
 SyntaxKind.ImportClause, SymbolFlags.Type;

crates/swc/tests/tsc-references/exportsAndImports1-amd.1.normal.js

@@ -56,6 +56,11 @@ define([
         E[E["C"] = 2] = "C";
     })(E || (E = {}));
     var D;
+    (function(D) {
+        D[D["A"] = 0] = "A";
+        D[D["B"] = 1] = "B";
+        D[D["C"] = 2] = "C";
+    })(D || (D = {}));
     var M;
     (function(M) {})(M || (M = {}));
     var a = M.x;

crates/swc/tests/tsc-references/exportsAndImports1-amd.2.minified.js

@@ -20,7 +20,7 @@ define([
             return C;
         },
         D: function() {
-            return D;
+            return D1;
         },
         E: function() {
             return E1;
@@ -38,12 +38,12 @@ define([
             return v;
         }
     });
-    var E, E1, D, M, v = 1;
+    var E, D, E1, D1, M, v = 1;
     function f() {}
     var C = function C() {
         _class_call_check._(this, C);
     };
-    (E = E1 || (E1 = {}))[E.A = 0] = "A", E[E.B = 1] = "B", E[E.C = 2] = "C", M || (M = {});
+    (E = E1 || (E1 = {}))[E.A = 0] = "A", E[E.B = 1] = "B", E[E.C = 2] = "C", (D = D1 || (D1 = {}))[D.A = 0] = "A", D[D.B = 1] = "B", D[D.C = 2] = "C", M || (M = {});
     var a = M.x;
 });
 //// [t2.ts]

crates/swc/tests/tsc-references/exportsAndImports1-es6.1.normal.js

@@ -45,6 +45,11 @@ var E;
     E[E["C"] = 2] = "C";
 })(E || (E = {}));
 var D;
+(function(D) {
+    D[D["A"] = 0] = "A";
+    D[D["B"] = 1] = "B";
+    D[D["C"] = 2] = "C";
+})(D || (D = {}));
 var M;
 (function(M) {})(M || (M = {}));
 const a = M.x;

crates/swc/tests/tsc-references/exportsAndImports1-es6.2.minified.js

@@ -12,7 +12,7 @@ Object.defineProperty(exports, "__esModule", {
         return C;
     },
     D: function() {
-        return D;
+        return D1;
     },
     E: function() {
         return E1;
@@ -30,11 +30,11 @@ Object.defineProperty(exports, "__esModule", {
         return v;
     }
 });
-var E, E1, D, M, v = 1;
+var E, D, E1, D1, M, v = 1;
 function f() {}
 class C {
 }
-(E = E1 || (E1 = {}))[E.A = 0] = "A", E[E.B = 1] = "B", E[E.C = 2] = "C", M || (M = {});
+(E = E1 || (E1 = {}))[E.A = 0] = "A", E[E.B = 1] = "B", E[E.C = 2] = "C", (D = D1 || (D1 = {}))[D.A = 0] = "A", D[D.B = 1] = "B", D[D.C = 2] = "C", M || (M = {});
 const a = M.x;
 //// [t2.ts]
 Object.defineProperty(exports, "__esModule", {

crates/swc/tests/tsc-references/exportsAndImports1.1.normal.js

@@ -48,6 +48,11 @@ var E;
     E[E["C"] = 2] = "C";
 })(E || (E = {}));
 var D;
+(function(D) {
+    D[D["A"] = 0] = "A";
+    D[D["B"] = 1] = "B";
+    D[D["C"] = 2] = "C";
+})(D || (D = {}));
 var M;
 (function(M) {})(M || (M = {}));
 var a = M.x;

crates/swc/tests/tsc-references/exportsAndImports1.2.minified.js

@@ -12,7 +12,7 @@ Object.defineProperty(exports, "__esModule", {
         return C;
     },
     D: function() {
-        return D;
+        return D1;
     },
     E: function() {
         return E1;
@@ -30,12 +30,12 @@ Object.defineProperty(exports, "__esModule", {
         return v;
     }
 });
-var E, E1, D, M, _class_call_check = require("@swc/helpers/_/_class_call_check"), v = 1;
+var E, D, E1, D1, M, _class_call_check = require("@swc/helpers/_/_class_call_check"), v = 1;
 function f() {}
 var C = function C() {
     _class_call_check._(this, C);
 };
-(E = E1 || (E1 = {}))[E.A = 0] = "A", E[E.B = 1] = "B", E[E.C = 2] = "C", M || (M = {});
+(E = E1 || (E1 = {}))[E.A = 0] = "A", E[E.B = 1] = "B", E[E.C = 2] = "C", (D = D1 || (D1 = {}))[D.A = 0] = "A", D[D.B = 1] = "B", D[D.C = 2] = "C", M || (M = {});
 var a = M.x;
 //// [t2.ts]
 Object.defineProperty(exports, "__esModule", {

crates/swc_ecma_transforms_typescript/src/transform.rs

@@ -287,18 +287,18 @@ impl Transform {
             }
 
             let id = stmt.get_decl_id();
-            stmt = self.fold_stmt(stmt);
+            stmt = self.fold_stmt(stmt, false);
             decl_id_record.extend(id);
             if !stmt.is_empty() {
                 n.push(stmt);
             }
         }
     }
 
-    fn fold_stmt(&mut self, n: Stmt) -> Stmt {
+    fn fold_stmt(&mut self, n: Stmt, is_export: bool) -> Stmt {
         match n {
             Stmt::Decl(Decl::TsModule(ts_module)) => self.transform_ts_module(*ts_module, false),
-            Stmt::Decl(Decl::TsEnum(ts_enum)) => self.transform_ts_enum(*ts_enum, false),
+            Stmt::Decl(Decl::TsEnum(ts_enum)) => self.transform_ts_enum(*ts_enum, is_export),
             stmt => stmt,
         }
     }
@@ -312,6 +312,8 @@ impl Transform {
             return;
         }
 
+        let export_names = self.collect_named_export(n);
+
         let mut decl_id_record = AHashSet::<Id>::default();
 
         for mut module_item in n.take().drain(..) {
@@ -342,15 +344,19 @@ impl Transform {
             }
 
             let id = module_item.get_decl_id();
-            module_item = self.fold_module_item(module_item);
+            let is_export = id
+                .as_ref()
+                .map(|id| export_names.contains(id))
+                .unwrap_or_default();
+            module_item = self.fold_module_item(module_item, is_export);
             decl_id_record.extend(id);
             if !matches!(module_item, ModuleItem::Stmt(Stmt::Empty(..))) {
                 n.push(module_item);
             }
         }
     }
 
-    fn fold_module_item(&mut self, n: ModuleItem) -> ModuleItem {
+    fn fold_module_item(&mut self, n: ModuleItem, is_export: bool) -> ModuleItem {
         match n {
             ModuleItem::ModuleDecl(ModuleDecl::ExportDecl(ExportDecl {
                 decl: Decl::TsModule(ts_module),
@@ -360,7 +366,7 @@ impl Transform {
                 decl: Decl::TsEnum(ts_enum),
                 ..
             })) => self.transform_ts_enum(*ts_enum, true).into(),
-            ModuleItem::Stmt(stmt @ Stmt::Decl(..)) => self.fold_stmt(stmt).into(),
+            ModuleItem::Stmt(stmt @ Stmt::Decl(..)) => self.fold_stmt(stmt, is_export).into(),
             module_item => module_item,
         }
     }
@@ -879,6 +885,41 @@ impl Transform {
 
         Factory::function(vec![ident.into()], body).as_call(DUMMY_SP, vec![init_arg.into()])
     }
+
+    fn collect_named_export(&self, n: &[ModuleItem]) -> AHashSet<Id> {
+        let mut names = AHashSet::default();
+
+        if self.namespace_id.is_some() {
+            return names;
+        }
+
+        for item in n {
+            match item {
+                ModuleItem::ModuleDecl(ModuleDecl::ExportNamed(NamedExport {
+                    specifiers,
+                    src: None,
+                    ..
+                })) => {
+                    names.extend(specifiers.iter().map(|s| match s {
+                        ExportSpecifier::Named(ExportNamedSpecifier {
+                            orig: ModuleExportName::Ident(export_id),
+                            ..
+                        }) => export_id.to_id(),
+                        _ => unreachable!("only named export is allowed for src = None"),
+                    }));
+                }
+                ModuleItem::ModuleDecl(ModuleDecl::ExportDefaultExpr(ExportDefaultExpr {
+                    expr,
+                    ..
+                })) if expr.is_ident() => {
+                    names.extend(expr.as_ident().map(Ident::to_id));
+                }
+                _ => {}
+            }
+        }
+
+        names
+    }
 }
 
 impl Transform {