fix(isolated-declarations): leading comments of ExportDefaultDeclaration and TSExportAssignment appear in incorrect places (#10559)

close: #10535

https://www.typescriptlang.org/play/?#code/PQKhCgAIUgTBTAZgQwK4BsAul4A8AOA9gE6ZQjDh5GlxJpaQCMADOOKBNJACoDKAUQIlMAQQDO4gJYBzAHYBbeHLLRKVYbQC8kRKjkBjTFMJzdhQgAoAlJADekYvEypiZlgF8gA

Author: Dunqing

crates/oxc_isolated_declarations/src/module.rs

@@ -52,24 +52,22 @@ impl<'a> IsolatedDeclarations<'a> {
                 Some((None, decl.declaration.clone_in(self.ast.allocator)))
             }
             declaration @ match_expression!(ExportDefaultDeclarationKind) => self
-                .transform_export_expression(declaration.to_expression())
+                .transform_export_expression(decl.span, declaration.to_expression())
                 .map(|(var_decl, expr)| (var_decl, ExportDefaultDeclarationKind::from(expr))),
         };
 
         declaration.map(|(var_decl, declaration)| {
             let exported =
                 ModuleExportName::IdentifierName(self.ast.identifier_name(SPAN, "default"));
-            let declaration = self.ast.module_declaration_export_default_declaration(
-                decl.span,
-                exported,
-                declaration,
-            );
+            let declaration =
+                self.ast.module_declaration_export_default_declaration(SPAN, exported, declaration);
             (var_decl, Statement::from(declaration))
         })
     }
 
     fn transform_export_expression(
         &self,
+        decl_span: Span,
         expr: &Expression<'a>,
     ) -> Option<(Option<Statement<'a>>, Expression<'a>)> {
         if matches!(expr, Expression::Identifier(_)) {
@@ -92,7 +90,7 @@ impl<'a> IsolatedDeclarations<'a> {
                 self.ast.vec1(self.ast.variable_declarator(SPAN, kind, id, None, false));
 
             let variable_statement = Statement::from(self.ast.declaration_variable(
-                SPAN,
+                decl_span,
                 kind,
                 declarations,
                 self.is_declare(),
@@ -105,10 +103,10 @@ impl<'a> IsolatedDeclarations<'a> {
         &self,
         decl: &TSExportAssignment<'a>,
     ) -> Option<(Option<Statement<'a>>, Statement<'a>)> {
-        self.transform_export_expression(&decl.expression).map(|(var_decl, expr)| {
+        self.transform_export_expression(decl.span, &decl.expression).map(|(var_decl, expr)| {
             (
                 var_decl,
-                Statement::from(self.ast.module_declaration_ts_export_assignment(decl.span, expr)),
+                Statement::from(self.ast.module_declaration_ts_export_assignment(SPAN, expr)),
             )
         })
     }

crates/oxc_isolated_declarations/tests/fixtures/export-default2.ts

@@ -0,0 +1,6 @@
+/**
+ * comment should be a leading comment of the arrow function
+ */
+export default () => {
+	return 0;
+};

crates/oxc_isolated_declarations/tests/fixtures/ts-export-assignment.ts

@@ -1,5 +1,8 @@
 const Res = 0;
 
+/**
+ * comment should be a leading comment of the function Foo
+ */
 export = function Foo(): typeof Res {
-  return Res;
-}
+	return Res;
+};

crates/oxc_isolated_declarations/tests/snapshots/export-default2.snap

@@ -0,0 +1,12 @@
+---
+source: crates/oxc_isolated_declarations/tests/mod.rs
+input_file: crates/oxc_isolated_declarations/tests/fixtures/export-default2.ts
+---
+```
+==================== .D.TS ====================
+
+/**
+* comment should be a leading comment of the arrow function
+*/
+declare const _default: () => number;
+export default _default;

crates/oxc_isolated_declarations/tests/snapshots/ts-export-assignment.snap

@@ -6,5 +6,8 @@ input_file: crates/oxc_isolated_declarations/tests/fixtures/ts-export-assignment
 ==================== .D.TS ====================
 
 declare const Res = 0;
+/**
+* comment should be a leading comment of the function Foo
+*/
 declare const _default: () => typeof Res;
 export = _default;