feat(transformer/typescript): support transform constructor method (#2551)

crates/oxc_transformer/src/lib.rs

@@ -313,4 +313,25 @@ impl<'a> VisitMut<'a> for Transformer<'a> {
             .as_mut()
             .map(|t: &mut JsonStrings| t.transform_string_literal(lit));
     }
+
+    fn visit_method_definition(&mut self, def: &mut MethodDefinition<'a>) {
+        let kind = AstKind::MethodDefinition(self.alloc(def));
+        self.enter_node(kind);
+
+        self.typescript.as_mut().map(|t| t.transform_method_definition(def));
+
+        for decorator in def.decorators.iter_mut() {
+            self.visit_decorator(decorator);
+        }
+
+        let flags = match def.kind {
+            MethodDefinitionKind::Get => ScopeFlags::GetAccessor,
+            MethodDefinitionKind::Set => ScopeFlags::SetAccessor,
+            MethodDefinitionKind::Constructor => ScopeFlags::Constructor,
+            MethodDefinitionKind::Method => ScopeFlags::empty(),
+        };
+        self.visit_property_key(&mut def.key);
+        self.visit_function(&mut def.value, Some(flags));
+        self.leave_node(kind);
+    }
 }

crates/oxc_transformer/src/typescript/mod.rs

@@ -728,4 +728,62 @@ impl<'a> TypeScript<'a> {
         let expr = self.ast.call_expression(SPAN, callee, arguments, false, None);
         self.ast.expression_statement(SPAN, expr)
     }
+
+    /// Transform constructor method
+    /// ```typescript
+    ///
+    /// constructor(public x) {
+    ///   super();
+    /// }
+    /// // to
+    /// constructor(x) {
+    ///   super();
+    ///   this.x = x;
+    /// }
+    /// ```
+    pub fn transform_method_definition(&mut self, def: &mut MethodDefinition<'a>) {
+        if !def.kind.is_constructor() {
+            return;
+        }
+
+        let mut params_name = vec![];
+        def.value.params.items.iter().for_each(|param| {
+            if !param.accessibility.is_some_and(|a| matches!(a, TSAccessibility::Public)) {
+                return;
+            }
+            match &param.pattern.kind {
+                BindingPatternKind::BindingIdentifier(ident) => {
+                    params_name.push(ident.name.clone());
+                }
+                BindingPatternKind::AssignmentPattern(pattern) => {
+                    if let BindingPatternKind::BindingIdentifier(ident) = &pattern.left.kind {
+                        params_name.push(ident.name.clone());
+                    }
+                }
+                _ => {}
+            }
+        });
+
+        let Some(body) = &mut def.value.body else {
+            return;
+        };
+
+        for name in params_name {
+            // TODO: We should push it before the super call
+            body.statements.push(self.ast.expression_statement(
+                SPAN,
+                self.ast.assignment_expression(
+                    SPAN,
+                    AssignmentOperator::Assign,
+                    self.ast.simple_assignment_target_member_expression(self.ast.static_member(
+                        SPAN,
+                        self.ast.this_expression(SPAN),
+                        IdentifierName::new(SPAN, name.clone()),
+                        false,
+                    )),
+                    self.ast.identifier_reference_expression(IdentifierReference::new(SPAN, name)),
+                ),
+            ));
+        }
+    }
 }

tasks/transform_conformance/babel.snap.md

@@ -1,4 +1,4 @@
-Passed: 349/1369
+Passed: 351/1369
 
 # All Passed:
 * babel-plugin-transform-numeric-separator
@@ -832,19 +832,17 @@ Passed: 349/1369
 * general/function-duplicate-name/input.js
 * general/object/input.js
 
-# babel-plugin-transform-typescript (95/158)
+# babel-plugin-transform-typescript (97/158)
 * class/abstract-class-decorated-method/input.ts
 * class/abstract-class-decorated-parameter/input.ts
 * class/accessor-allowDeclareFields-false/input.ts
 * class/accessor-allowDeclareFields-true/input.ts
 * class/declare/input.ts
 * class/decorated-declare-properties/input.ts
-* class/parameter-properties/input.ts
 * class/parameter-properties-late-super/input.ts
 * class/parameter-properties-with-class/input.ts
 * class/parameter-properties-with-class-and-super/input.ts
 * class/parameter-properties-with-parameters/input.ts
-* class/parameter-properties-with-super/input.ts
 * class/private-method-override-transform-private/input.ts
 * class/transform-properties-declare-wrong-order/input.ts
 * exports/declared-types/input.ts