feat(codegen): print readonly keyword for TSIndexSignature

crates/oxc_codegen/src/gen.rs

@@ -3025,8 +3025,7 @@ impl<'a, const MINIFY: bool> Gen<MINIFY> for TSSignature<'a> {
             Self::TSIndexSignature(signature) => signature.gen(p, ctx),
             Self::TSPropertySignature(signature) => {
                 if signature.readonly {
-                    p.print_str(b"readonly");
-                    p.print_hard_space();
+                    p.print_str(b"readonly ");
                 }
                 if signature.computed {
                     p.print(b'[');
@@ -3191,6 +3190,9 @@ impl<'a, const MINIFY: bool> Gen<MINIFY> for TSTypeParameterInstantiation<'a> {
 
 impl<'a, const MINIFY: bool> Gen<MINIFY> for TSIndexSignature<'a> {
     fn gen(&self, p: &mut Codegen<{ MINIFY }>, ctx: Context) {
+        if self.readonly {
+            p.print_str(b"readonly ");
+        }
         p.print_str(b"[");
         for (index, parameter) in self.parameters.iter().enumerate() {
             if index != 0 {

crates/oxc_isolated_declarations/tests/fixtures/readonly.ts

@@ -0,0 +1,4 @@
+export const EMPTY_OBJ: { readonly [key: string]: any } = __DEV__
+  ? Object.freeze({})
+  : {}
+export const EMPTY_ARR: readonly never[] = __DEV__ ? Object.freeze([]) : []

crates/oxc_isolated_declarations/tests/snapshots/readonly.snap

@@ -0,0 +1,8 @@
+---
+source: crates/oxc_isolated_declarations/tests/mod.rs
+input_file: crates/oxc_isolated_declarations/tests/fixtures/readonly.ts
+---
+==================== .D.TS ====================
+
+export declare const EMPTY_OBJ: {readonly [key: string]: any};
+export declare const EMPTY_ARR: readonly (never)[];