1 files changed, 26 insertions, 2 deletions

diff --git a/js/public/Class.h b/js/public/Class.h
index 094e4a7ed7..6f1960a308 100644
--- a/js/public/Class.h
+++ b/js/public/Class.h
@@ -131,16 +131,24 @@ class ObjectOpResult
         Uninitialized = uintptr_t(-1)
     };
 
+    static const uintptr_t SoftFailBit = uintptr_t(1) << (sizeof(uintptr_t) * 8 - 1);
+
     ObjectOpResult() : code_(Uninitialized) {}
 
-    /* Return true if succeed() was called. */
+    /* Return true if succeed() or failSoft() was called. */
     bool ok() const {
         MOZ_ASSERT(code_ != Uninitialized);
-        return code_ == OkCode;
+        return code_ == OkCode || (code_ & SoftFailBit);
     }
 
     explicit operator bool() const { return ok(); }
 
+    /* Return true if succeed() was called. */
+    bool confirmOk() const {
+        MOZ_ASSERT(code_ != Uninitialized);
+        return code_ == OkCode;
+    }
+
     /* Set this ObjectOpResult to true and return true. */
     bool succeed() {
         code_ = OkCode;
@@ -160,10 +168,26 @@ class ObjectOpResult
      */
     bool fail(uint32_t msg) {
         MOZ_ASSERT(msg != OkCode);
+        MOZ_ASSERT((msg & SoftFailBit) == 0);
         code_ = msg;
         return true;
     }
 
+    /*
+     * DEPRECATED: This is a non-standard compatibility hack.
+     *
+     * Set this ObjectOpResult to true, but remembers an error code.
+     * This is used for situations where we really want to fail,
+     * but can't for legacy reasons.
+     *
+     * Always returns true, as a convenience.
+     */
+    bool failSoft(uint32_t msg) {
+        // The msg code is currently never extracted again.
+        code_ = msg | SoftFailBit;
+        return true;
+    }
+
     JS_PUBLIC_API(bool) failCantRedefineProp();
     JS_PUBLIC_API(bool) failReadOnly();
     JS_PUBLIC_API(bool) failGetterOnly();