feat(transformer/typescript): report error for export = <value> (#3021)

crates/oxc_transformer/src/lib.rs

@@ -210,7 +210,6 @@ impl<'a> VisitMut<'a> for Transformer<'a> {
     }
 
     fn visit_statement(&mut self, stmt: &mut Statement<'a>) {
-        self.x0_typescript.transform_statement(stmt);
         walk_mut::walk_statement_mut(self, stmt);
     }
 
@@ -223,4 +222,9 @@ impl<'a> VisitMut<'a> for Transformer<'a> {
         self.x0_typescript.transform_if_statement(stmt);
         walk_mut::walk_if_statement_mut(self, stmt);
     }
+
+    fn visit_module_declaration(&mut self, decl: &mut ModuleDeclaration<'a>) {
+        self.x0_typescript.transform_module_declaration(decl);
+        walk_mut::walk_module_declaration_mut(self, decl);
+    }
 }

crates/oxc_transformer/src/typescript/annotations.rs

@@ -32,26 +32,6 @@ impl<'a> TypeScriptAnnotations<'a> {
         }
     }
 
-    // Convert `export = expr` into `module.exports = expr`
-    fn create_module_exports(&self, exp: &TSExportAssignment<'a>) -> Statement<'a> {
-        let ast = &self.ctx.ast;
-
-        ast.expression_statement(
-            SPAN,
-            ast.assignment_expression(
-                SPAN,
-                AssignmentOperator::Assign,
-                ast.simple_assignment_target_member_expression(ast.static_member(
-                    SPAN,
-                    ast.identifier_reference_expression(ast.identifier_reference(SPAN, "module")),
-                    ast.identifier_name(SPAN, "exports"),
-                    false,
-                )),
-                ast.copy(&exp.expression),
-            ),
-        )
-    }
-
     // Creates `this.name = name`
     fn create_this_property_assignment(&self, name: &Atom<'a>) -> Statement<'a> {
         let ast = &self.ctx.ast;
@@ -315,7 +295,6 @@ impl<'a> TypeScriptAnnotations<'a> {
         // Remove TS specific statements
         stmts.retain(|stmt| match stmt {
             Statement::ExpressionStatement(s) => !s.expression.is_typescript_syntax(),
-            Statement::Declaration(s) => !s.is_typescript_syntax(),
             // Ignore ModuleDeclaration as it's handled in the program
             _ => true,
         });
@@ -373,12 +352,4 @@ impl<'a> TypeScriptAnnotations<'a> {
     ) {
         expr.type_parameters = None;
     }
-
-    pub fn transform_statement(&mut self, decl: &mut Statement<'a>) {
-        if let Statement::ModuleDeclaration(module_decl) = decl {
-            if let ModuleDeclaration::TSExportAssignment(exp) = &mut **module_decl {
-                *decl = self.create_module_exports(exp);
-            }
-        }
-    }
 }

crates/oxc_transformer/src/typescript/diagnostics.rs

@@ -8,3 +8,8 @@ use oxc_span::Span;
 #[error("`import lib = require(...);` is only supported when compiling modules to CommonJS.\nPlease consider using `import lib from '...';` alongside Typescript's --allowSyntheticDefaultImports option, or add @babel/plugin-transform-modules-commonjs to your Babel config.")]
 #[diagnostic(severity(warning))]
 pub struct ImportEqualsRequireUnsupported(#[label] pub Span);
+
+#[derive(Debug, Error, Diagnostic)]
+#[error("`export = <value>;` is only supported when compiling modules to CommonJS.\nPlease consider using `export default <value>;`, or add @babel/plugin-transform-modules-commonjs to your Babel config.")]
+#[diagnostic(severity(warning))]
+pub struct ExportAssignmentUnsupported(#[label] pub Span);

crates/oxc_transformer/src/typescript/mod.rs

@@ -156,10 +156,6 @@ impl<'a> TypeScript<'a> {
         self.reference_collector.visit_identifier_reference(ident);
     }
 
-    pub fn transform_statement(&mut self, stmt: &mut Statement<'a>) {
-        self.annotations.transform_statement(stmt);
-    }
-
     pub fn transform_declaration(&mut self, decl: &mut Declaration<'a>) {
         match decl {
             Declaration::TSImportEqualsDeclaration(ts_import_equals)
@@ -175,4 +171,10 @@ impl<'a> TypeScript<'a> {
             _ => {}
         }
     }
+
+    pub fn transform_module_declaration(&mut self, module_decl: &mut ModuleDeclaration<'a>) {
+        if let ModuleDeclaration::TSExportAssignment(ts_export_assignment) = &mut *module_decl {
+            self.transform_ts_export_assignment(ts_export_assignment);
+        }
+    }
 }

crates/oxc_transformer/src/typescript/module.rs

@@ -2,7 +2,10 @@ use oxc_allocator::Box;
 use oxc_ast::ast::*;
 use oxc_span::SPAN;
 
-use super::{diagnostics::ImportEqualsRequireUnsupported, TypeScript};
+use super::{
+    diagnostics::{ExportAssignmentUnsupported, ImportEqualsRequireUnsupported},
+    TypeScript,
+};
 
 impl<'a> TypeScript<'a> {
     fn transform_ts_type_name(&self, type_name: &mut TSTypeName<'a>) -> Expression<'a> {
@@ -70,4 +73,14 @@ impl<'a> TypeScript<'a> {
 
         Declaration::VariableDeclaration(variable_declaration)
     }
+
+    pub fn transform_ts_export_assignment(
+        &mut self,
+        export_assignment: &mut TSExportAssignment<'a>,
+    ) {
+        println!("{:?}", self.ctx.source_type());
+        if self.ctx.source_type().is_module() {
+            self.ctx.error(ExportAssignmentUnsupported(export_assignment.span));
+        }
+    }
 }

tasks/transform_conformance/babel.snap.md

@@ -1,4 +1,4 @@
-Passed: 152/209
+Passed: 153/209
 
 # All Passed:
 * babel-plugin-transform-react-jsx-source
@@ -17,13 +17,12 @@ Passed: 152/209
 * opts/optimizeConstEnums/input.ts
 * opts/rewriteImportExtensions/input.ts
 
-# babel-plugin-transform-typescript (96/139)
+# babel-plugin-transform-typescript (97/139)
 * class/accessor-allowDeclareFields-false/input.ts
 * class/accessor-allowDeclareFields-true/input.ts
 * exports/declared-types/input.ts
 * exports/export-const-enums/input.ts
 * exports/export-type-star-from/input.ts
-* exports/export=/input.ts
 * imports/enum-id/input.ts
 * imports/enum-value/input.ts
 * imports/type-only-export-specifier-2/input.ts