Adjust flag d indices for emulation groups when using subclass

spec/regex-tag.spec.js

@@ -157,6 +157,13 @@ describe('regex', () => {
         expect([...'ab'.matchAll(regex({flags: 'g', subclass: false})`(?>(?<a>.))(?<b>.)`)][0][2]).not.toBe('b');
         expect('ab'.split(regex({subclass: false})`(?>(?<a>.))(?<b>.)`)).not.toEqual(['', 'a', 'b', '']);
       });
+
+      it('should adjust indices with flag d for emulation groups', () => {
+        expect(regex({flags: 'd', subclass: true})`(?>.)`.exec('a').indices).toHaveSize(1);
+
+        // Documenting behavior when the option is not used
+        expect(regex({flags: 'd', subclass: false})`(?>.)`.exec('a').indices).toHaveSize(2);
+      });
     });
   });
 });

src/regex.js

@@ -243,12 +243,20 @@ class WrappedRegExp extends RegExp {
     if (!match || !this.#captureMap) {
       return match;
     }
-    const copy = [...match];
+    const matchCopy = [...match];
     // Empty all but the first value of the array while preserving its other properties
     match.length = 1;
-    for (let i = 1; i < copy.length; i++) {
+    let indicesCopy;
+    if (this.hasIndices) {
+      indicesCopy = [...match.indices];
+      match.indices.length = 1;
+    }
+    for (let i = 1; i < matchCopy.length; i++) {
       if (this.#captureMap[i]) {
-        match.push(copy[i]);
+        match.push(matchCopy[i]);
+        if (this.hasIndices) {
+          match.indices.push(indicesCopy[i]);
+        }
       }
     }
     return match;