Call return() method of Set-like iterators (#1167)

Change the behavior of the following methods:

- Set.prototype.isDisjointFrom
- Set.prototype.isSupersetOf

Specifically, for iterators coming from set-like objects:

- DO NOT invoke return() when the iterator is exhausted
- DO invoke return() when the iterator is NOT exhausted

test262 doesn't test it but the spec seems to mandate it and V8 and SM
both implement it.

Author: bnoordhuis

quickjs.c

@@ -49450,7 +49450,7 @@ static JSValue js_set_isDisjointFrom(JSContext *ctx, JSValueConst this_val,
         if (JS_IsException(next))
             goto exception;
         found = false;
-        do {
+        for (;;) {
             item = JS_IteratorNext(ctx, iter, next, 0, NULL, &done);
             if (JS_IsException(item))
                 goto exception;
@@ -49459,7 +49459,12 @@ static JSValue js_set_isDisjointFrom(JSContext *ctx, JSValueConst this_val,
             item = map_normalize_key(ctx, item);
             found = (NULL != map_find_record(ctx, s, item));
             JS_FreeValue(ctx, item);
-        } while (!found);
+            if (!found)
+                continue;
+            if (JS_IteratorClose(ctx, iter, /*is_exception_pending*/false) < 0)
+                goto exception;
+            break;
+        }
     } else {
         iter = js_create_map_iterator(ctx, this_val, 0, NULL, MAGIC_SET);
         if (JS_IsException(iter))
@@ -49576,7 +49581,7 @@ static JSValue js_set_isSupersetOf(JSContext *ctx, JSValueConst this_val,
     if (JS_IsException(next))
         goto exception;
     found = true;
-    do {
+    for (;;) {
         item = JS_IteratorNext(ctx, iter, next, 0, NULL, &done);
         if (JS_IsException(item))
             goto exception;
@@ -49585,7 +49590,12 @@ static JSValue js_set_isSupersetOf(JSContext *ctx, JSValueConst this_val,
         item = map_normalize_key(ctx, item);
         found = (NULL != map_find_record(ctx, s, item));
         JS_FreeValue(ctx, item);
-    } while (found);
+        if (found)
+            continue;
+        if (JS_IteratorClose(ctx, iter, /*is_exception_pending*/false) < 0)
+            goto exception;
+        break;
+    }
 fini:
     rval = found ? JS_TRUE : JS_FALSE;
 exception:

tests/test_builtin.js

@@ -908,6 +908,48 @@ function test_weak_map()
     /* the WeakMap should be empty here */
 }
 
+function test_set()
+{
+    const iter = {
+        a: [4, 5, 6],
+        nextCalls: 0,
+        returnCalls: 0,
+        next() {
+            const done = this.nextCalls >= this.a.length
+            const value = this.a[this.nextCalls]
+            this.nextCalls++
+            return {done, value}
+        },
+        return() {
+            this.returnCalls++
+            return this
+        },
+    }
+    const setlike = {
+        size: iter.a.length,
+        has(v) { return iter.a.includes(v) },
+        keys() { return iter },
+    }
+    // set must be bigger than iter.a to hit iter.next and iter.return
+    assert(new Set([4,5,6,7]).isSupersetOf(setlike), true)
+    assert(iter.nextCalls, 4);
+    assert(iter.returnCalls, 0);
+    iter.nextCalls = iter.returnCalls = 0
+    assert(new Set([0,1,2,3]).isSupersetOf(setlike), false)
+    assert(iter.nextCalls, 1);
+    assert(iter.returnCalls, 1);
+    iter.nextCalls = iter.returnCalls = 0
+    // set must be bigger than iter.a to hit iter.next and iter.return
+    assert(new Set([4,5,6,7]).isDisjointFrom(setlike), false)
+    assert(iter.nextCalls, 1);
+    assert(iter.returnCalls, 1);
+    iter.nextCalls = iter.returnCalls = 0
+    assert(new Set([0,1,2,3]).isDisjointFrom(setlike), true)
+    assert(iter.nextCalls, 4);
+    assert(iter.returnCalls, 0);
+    iter.nextCalls = iter.returnCalls = 0
+}
+
 function test_weak_set()
 {
     var a, e;
@@ -1103,6 +1145,7 @@ test_regexp();
 test_symbol();
 test_map();
 test_weak_map();
+test_set();
 test_weak_set();
 test_generator();
 test_proxy_iter();