1 files changed, 212 insertions, 0 deletions
diff --git a/js/src/tests/non262/JSON/stringify-fastpath.js b/js/src/tests/non262/JSON/stringify-fastpath.js
new file mode 100644
index 0000000000..3b1d9e3021
--- /dev/null
+++ b/js/src/tests/non262/JSON/stringify-fastpath.js
@@ -0,0 +1,212 @@
+// |reftest| skip-if(!xulRuntime.shell) -- not sure why, but invisible errors when running in browser.
+
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * https://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+if (typeof JSONStringify === "undefined") {
+    var JSONStringify = SpecialPowers.Cu.getJSTestingFunctions().JSONStringify;
+}
+
+var report = this.console?.error || this.printErr;
+
+report("BUGNUMBER: 1837410");
+
+function compare(obj) {
+    let slow;
+    try { slow = JSONStringify(obj, "SlowOnly"); } catch (e) { slow = "" + e; }
+    let maybeFast;
+    try { maybeFast = JSONStringify(obj, "Normal"); } catch (e) { maybeFast = "" + e; }
+    if (slow !== maybeFast) {
+        report(`Slow:\n${slow}\nFast:\n${maybeFast}`);
+        return 1;
+    }
+    return 0;
+}
+
+function newBigInt(val = 7n) {
+    let result;
+    function grabThis() { result = this; }
+    grabThis.call(BigInt(val));
+    return result;
+}
+
+function testBothPaths() {
+    let failures = 0;
+    failures += compare([, 3, undefined, ,]);
+    failures += compare({ a: 1, b: undefined });
+    failures += compare({ a: undefined, b: 1 });
+    failures += compare({ a: 1, b: Symbol("fnord") });
+
+    const obj = {};
+    obj.first = true;
+    obj[0] = 'a';
+    obj[1] = undefined;
+    obj[2] = 'b';
+    obj.last = true;
+    failures += compare(obj);
+
+    const cyclic = {};
+    cyclic.one = 1;
+    cyclic.two = { me: cyclic };
+    failures += compare(cyclic);
+
+    const sparse = [10, 20, 30];
+    sparse[1000] = 40;
+    failures += compare(sparse);
+
+    const arr = [10, 20, 30];
+    arr.other = true;
+    failures += compare(arr);
+
+    const arr2 = new Array(5);
+    arr2[1] = 'hello';
+    arr2[3] = 'world';
+    failures += compare(arr2);
+
+    const big = { p1: 1, p2: 2, p3: 3, p4: 4, p5: 5, p6: 6, p7: 7, p8: 8, p9: 9 };
+    failures += compare(big);
+
+    failures += compare(new Number(3));
+    failures += compare(new Boolean(true));
+    failures += compare(Number.NaN);
+    failures += compare(undefined);
+    failures += compare({ x: () => 1 });
+
+    failures += compare({ x: newBigInt() });
+
+    const sparse2 = [];
+    Object.defineProperty(sparse2, "0", { value: 7, enumerable: false });
+    failures += compare(sparse2);
+
+    return failures;
+}
+
+function checkFast(value, expectWhySlow) {
+    let whySlow;
+    let json;
+    try {
+        json = JSONStringify(value, "FastOnly");
+    } catch (e) {
+        const m = e.message.match(/failed mandatory fast path: (\S+)/);
+        if (!m) {
+            report("Expected fast path fail, got " + e);
+            return 1;
+        }
+        whySlow = m[1];
+    }
+
+    if (expectWhySlow) {
+        if (!whySlow) {
+            report("Expected to bail out of fast path but unexpectedly succeeded");
+            report((new Error).stack);
+            report(json);
+            return 1;
+        } else if (whySlow != expectWhySlow) {
+            report(`Expected to bail out of fast path because ${expectWhySlow} but bailed because ${whySlow}`);
+            return 1;
+        }
+    } else {
+        if (whySlow) {
+            report("Expected fast path to succeed, bailed because: " + whySlow);
+            return 1; // Fail
+        }
+    }
+
+    return 0;
+}
+
+function testFastPath() {
+    let failures = 0;
+    failures += checkFast({});
+    failures += checkFast([]);
+    failures += checkFast({ x: true });
+    failures += checkFast([, , 10, ,]);
+    failures += checkFast({ x: undefined });
+    failures += checkFast({ x: Symbol() });
+    failures += checkFast({ x: new Set([10,20,30]) });
+
+    failures += checkFast("primitive", "PRIMITIVE");
+    failures += checkFast(true, "PRIMITIVE");
+    failures += checkFast(7, "PRIMITIVE");
+
+    failures += checkFast({ x: new Uint8Array(3) }, "INELIGIBLE_OBJECT");
+    failures += checkFast({ x: new Number(3) }, "INELIGIBLE_OBJECT");
+    failures += checkFast({ x: new Boolean(true) }, "INELIGIBLE_OBJECT");
+    failures += checkFast({ x: newBigInt(3) }, "INELIGIBLE_OBJECT");
+    failures += checkFast(Number.NaN, "PRIMITIVE");
+    failures += checkFast(undefined, "PRIMITIVE");
+
+    // Array has enumerated indexed + non-indexed slots.
+    const nonElements = [];
+    Object.defineProperty(nonElements, 0, { value: "hi", enumerated: true, configurable: true });
+    nonElements.named = 7;
+    failures += checkFast(nonElements, "INELIGIBLE_OBJECT");
+
+    nonElements.splice(0);
+    failures += checkFast(nonElements);
+
+    // Array's prototype has indexed slot and/or inherited element.
+    const proto = {};
+    Object.defineProperty(proto, "0", { value: 1, enumerable: false });
+    const holy = [, , 3];
+    Object.setPrototypeOf(holy, proto);
+    failures += checkFast(holy, "INELIGIBLE_OBJECT");
+    Object.setPrototypeOf(holy, { 1: true });
+    failures += checkFast(holy, "INELIGIBLE_OBJECT");
+
+    // This is probably redundant with one of the above, but it was
+    // found by a fuzzer at one point.
+    const accessorProto = Object.create(Array.prototype);
+    Object.defineProperty(accessorProto, "0", {
+        get() { return 2; }, set() { }
+    });
+    const child = [];
+    Object.setPrototypeOf(child, accessorProto);
+    child.push(1);
+    failures += checkFast(child, "INELIGIBLE_OBJECT");
+
+    failures += checkFast({ get x() { return 1; } }, "NON_DATA_PROPERTY");
+
+    const self = {};
+    self.self = self;
+    failures += checkFast(self, "DEEP_RECURSION");
+    const ouroboros = ['head', 'middle', []];
+    let p = ouroboros[2];
+    let middle;
+    for (let i = 0; i < 1000; i++) {
+        p.push('middle', 'middle');
+        p = p[2] = [];
+        if (i == 10) {
+            middle = p;
+        }
+    }
+    failures += checkFast(ouroboros, "DEEP_RECURSION"); // Acyclic but deep
+    p[2] = ouroboros;
+    failures += checkFast(ouroboros, "DEEP_RECURSION"); // Cyclic and deep
+    middle[2] = ouroboros;
+    failures += checkFast(ouroboros, "DEEP_RECURSION"); // Cyclic after 10 recursions
+
+    failures += checkFast({ 0: true, 1: true, 10000: true }, "INELIGIBLE_OBJECT");
+    const arr = [1, 2, 3];
+    arr[10000] = 4;
+    failures += checkFast(arr, "INELIGIBLE_OBJECT");
+
+    failures += checkFast({ x: 12n }, "BIGINT");
+
+    failures += checkFast({ x: new Date() }, "HAVE_TOJSON");
+    failures += checkFast({ toJSON() { return "json"; } }, "HAVE_TOJSON");
+    const custom = { toJSON() { return "value"; } };
+    failures += checkFast(Object.create(custom), "HAVE_TOJSON");
+
+    return failures;
+}
+
+let failures = testBothPaths() + testFastPath();
+
+if (typeof reportCompare === "function") {
+    reportCompare(0, failures);
+} else {
+    assertEq(failures, 0);
+}