Bug 1474385 - Part 1: Rename and comment a Debugger method involved in error handling. r=jimb

We will in fact delete this method later in the stack, but to understand those
coming patches, it helps to understand what's going on here.

--HG--
extra : rebase_source : a8532831cb37aab4e346a58db09a9c7a7496de1b

js/src/vm/Debugger.cpp

@@ -1422,8 +1422,11 @@ Debugger::handleUncaughtExceptionHelper(Maybe<AutoRealm>& ar, MutableHandleValue
             if (js::Call(cx, fval, object, exc, &rv)) {
                 if (vp) {
                     ResumeMode resumeMode = ResumeMode::Continue;
-                    if (processResumptionValue(ar, frame, thisVForCheck, rv, resumeMode, *vp))
+                    if (processResumptionValueNoUncaughtExceptionHook(ar, frame, thisVForCheck, rv,
+                                                                      resumeMode, *vp))
+                    {
                         return resumeMode;
+                    }
                 } else {
                     return ResumeMode::Continue;
                 }
@@ -1634,9 +1637,10 @@ GetThisValueForCheck(JSContext* cx, AbstractFramePtr frame, jsbytecode* pc,
 }
 
 bool
-Debugger::processResumptionValue(Maybe<AutoRealm>& ar, AbstractFramePtr frame,
-                                 const Maybe<HandleValue>& maybeThisv, HandleValue rval,
-                                 ResumeMode& resumeMode, MutableHandleValue vp)
+Debugger::processResumptionValueNoUncaughtExceptionHook(
+    Maybe<AutoRealm>& ar, AbstractFramePtr frame,
+    const Maybe<HandleValue>& maybeThisv, HandleValue rval,
+    ResumeMode& resumeMode, MutableHandleValue vp)
 {
     JSContext* cx = ar->context();
 

js/src/vm/Debugger.h

@@ -607,7 +607,7 @@ class Debugger : private mozilla::LinkedListElement<Debugger>
      *
      * Precondition: ar is entered. We are in the debugger compartment.
      *
-     * Postcondition: This called ar.leave(). See handleUncaughtException.
+     * Postcondition: This called ar.reset(). See handleUncaughtException.
      *
      * If `success` is false, the hook failed. If an exception is pending in
      * ar.context(), return handleUncaughtException(ar, vp, callhook).
@@ -644,9 +644,19 @@ class Debugger : private mozilla::LinkedListElement<Debugger>
                                                 bool success, ResumeMode resumeMode,
                                                 MutableHandleValue vp);
 
-    bool processResumptionValue(mozilla::Maybe<AutoRealm>& ar, AbstractFramePtr frame,
-                                const mozilla::Maybe<HandleValue>& maybeThis, HandleValue rval,
-                                ResumeMode& resumeMode, MutableHandleValue vp);
+    /*
+     * Like processHandlerResult, but if `rval` is not a valid resumption value,
+     * don't call the uncaughtExceptionHook. Just return false.
+     *
+     * This is used to process the return value of the uncaughtExceptionHook
+     * itself, to avoid the possibility of triggering it again.
+     */
+    bool processResumptionValueNoUncaughtExceptionHook(mozilla::Maybe<AutoRealm>& ar,
+                                                       AbstractFramePtr frame,
+                                                       const mozilla::Maybe<HandleValue>& maybeThis,
+                                                       HandleValue rval,
+                                                       ResumeMode& resumeMode,
+                                                       MutableHandleValue vp);
 
     GlobalObject* unwrapDebuggeeArgument(JSContext* cx, const Value& v);