fix decorator and declare (#3828)

* return the prop if there are decorators

* test and comment

3 files changed, 31 insertions, 1 deletions

diff --git a/src/js_ast.zig b/src/js_ast.zig
index b5f47474a..358fe3197 100644
--- a/src/js_ast.zig
+++ b/src/js_ast.zig
@@ -840,6 +840,7 @@ pub const G = struct {
             get,
             set,
             spread,
+            declare,
             class_static_block,
 
             pub fn jsonStringify(self: @This(), opts: anytype, o: anytype) !void {
diff --git a/src/js_parser.zig b/src/js_parser.zig
index 6390dfdba..076815e54 100644
--- a/src/js_parser.zig
+++ b/src/js_parser.zig
@@ -12062,7 +12062,14 @@ fn NewParser_(
                                         // https://github.com/oven-sh/bun/issues/1907
                                         if (opts.is_class and is_typescript_enabled and strings.eqlComptime(raw, "declare")) {
                                             const scope_index = p.scopes_in_order.items.len;
-                                            _ = try p.parseProperty(kind, opts, null);
+                                            if (try p.parseProperty(kind, opts, null)) |_prop| {
+                                                var prop = _prop;
+                                                if (prop.kind == .normal and prop.value == null and opts.ts_decorators.len > 0) {
+                                                    prop.kind = .declare;
+                                                    return prop;
+                                                }
+                                            }
+
                                             p.discardScopesUpTo(scope_index);
                                             return null;
                                         }
@@ -19512,6 +19519,8 @@ fn NewParser_(
                             }
                         }
 
+                        // TODO: prop.kind == .declare and prop.value == null
+
                         if (prop.ts_decorators.len > 0) {
                             const loc = prop.key.?.loc;
                             const descriptor_key = switch (prop.key.?.data) {
diff --git a/test/transpiler/decorators.test.ts b/test/transpiler/decorators.test.ts
index 100ecc3bc..885391800 100644
--- a/test/transpiler/decorators.test.ts
+++ b/test/transpiler/decorators.test.ts
@@ -998,3 +998,23 @@ test("export default class Named works", () => {
 test("export default class works (anonymous name)", () => {
   expect(new DecoratedAnonClass()["methoddecorated"]).toBe(true);
 });
+
+test("decorator and declare", () => {
+  let counter = 0;
+  function d1(t) {
+    t();
+  }
+  class A {
+    @d1(() => {
+      counter++;
+    })
+    declare a: number;
+
+    m() {
+      counter++;
+    }
+  }
+
+  new A();
+  expect(counter).toBe(1);
+});