Bug 1571092 - Mark various MozPromise-returning methods MOZ_MUST_USE. r=jld

Differential Revision: https://phabricator.services.mozilla.com/D40528

--HG--
extra : moz-landing-system : lando

xpcom/threads/MozPromise.h

@@ -246,8 +246,8 @@ class MozPromise : public MozPromiseBase {
   class Private;
 
   template <typename ResolveValueType_>
-  static RefPtr<MozPromise> CreateAndResolve(ResolveValueType_&& aResolveValue,
-                                             const char* aResolveSite) {
+  static MOZ_MUST_USE RefPtr<MozPromise> CreateAndResolve(
+      ResolveValueType_&& aResolveValue, const char* aResolveSite) {
     static_assert(IsConvertible<ResolveValueType_, ResolveValueT>::value,
                   "Resolve() argument must be implicitly convertible to "
                   "MozPromise's ResolveValueT");
@@ -258,8 +258,8 @@ class MozPromise : public MozPromiseBase {
   }
 
   template <typename RejectValueType_>
-  static RefPtr<MozPromise> CreateAndReject(RejectValueType_&& aRejectValue,
-                                            const char* aRejectSite) {
+  static MOZ_MUST_USE RefPtr<MozPromise> CreateAndReject(
+      RejectValueType_&& aRejectValue, const char* aRejectSite) {
     static_assert(IsConvertible<RejectValueType_, RejectValueT>::value,
                   "Reject() argument must be implicitly convertible to "
                   "MozPromise's RejectValueT");
@@ -270,7 +270,7 @@ class MozPromise : public MozPromiseBase {
   }
 
   template <typename ResolveOrRejectValueType_>
-  static RefPtr<MozPromise> CreateAndResolveOrReject(
+  static MOZ_MUST_USE RefPtr<MozPromise> CreateAndResolveOrReject(
       ResolveOrRejectValueType_&& aValue, const char* aSite) {
     RefPtr<typename MozPromise::Private> p = new MozPromise::Private(aSite);
     p->ResolveOrReject(std::forward<ResolveOrRejectValueType_>(aValue), aSite);
@@ -330,8 +330,9 @@ class MozPromise : public MozPromiseBase {
   };
 
  public:
-  static RefPtr<AllPromiseType> All(nsISerialEventTarget* aProcessingTarget,
-                                    nsTArray<RefPtr<MozPromise>>& aPromises) {
+  static MOZ_MUST_USE RefPtr<AllPromiseType> All(
+      nsISerialEventTarget* aProcessingTarget,
+      nsTArray<RefPtr<MozPromise>>& aPromises) {
     if (aPromises.Length() == 0) {
       return AllPromiseType::CreateAndResolve(nsTArray<ResolveValueType>(),
                                               __func__);
@@ -940,7 +941,7 @@ class MozPromise : public MozPromiseBase {
 
 #  ifdef MOZ_WIDGET_ANDROID
   // Creates a C++ MozPromise from its Java counterpart, GeckoResult.
-  static RefPtr<MozPromise> FromGeckoResult(
+  static MOZ_MUST_USE RefPtr<MozPromise> FromGeckoResult(
       java::GeckoResult::Param aGeckoResult) {
     using jni::GeckoResultCallback;
     RefPtr<Private> p = new Private("GeckoResult Glue", false);