Bug 736501 - Use -Werror=unused-result, r=ted/mayhemer/njn

--HG--
extra : rebase_source : 121cddcd66f9be9b80840b47aecbe95307bae0ab

configure.in

@@ -1748,11 +1748,15 @@ if test "$GNU_CC"; then
     # -Werror=return-type - catches missing returns, zero false positives
     # -Wtype-limits - catches overflow bugs, few false positives
     # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
-    #
+    # -Werror=unused-result - enforces __attribute__((warn_unused_result));
+    #     Seldom used in system headers, but frequently in Mozilla code to
+    #     enforce checking of fallible methods.
+
     _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wall -Wpointer-arith -Wdeclaration-after-statement"
     MOZ_C_SUPPORTS_WARNING(-W, error=return-type, ac_c_has_werror_return_type)
     MOZ_C_SUPPORTS_WARNING(-W, type-limits, ac_c_has_wtype_limits)
     MOZ_C_SUPPORTS_WARNING(-W, empty-body, ac_c_has_wempty_body)
+    MOZ_C_SUPPORTS_WARNING(-W, error=unused-result, ac_c_has_werror_unused_result)
     
     # Turn off the following warnings that -Wall/-pedantic turn on:
     # -Wno-unused - lots of violations in third-party code
@@ -1815,11 +1819,13 @@ if test "$GNU_CXX"; then
     # -Werror=return-type - catches missing returns, zero false positives
     # -Wtype-limits - catches overflow bugs, few false positives
     # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
-    #
+    # -Werror=unused-result - see above
+
     _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wall -Wpointer-arith -Woverloaded-virtual"
     MOZ_CXX_SUPPORTS_WARNING(-W, error=return-type, ac_cxx_has_werror_return_type)
     MOZ_CXX_SUPPORTS_WARNING(-W, type-limits, ac_cxx_has_wtype_limits)
     MOZ_CXX_SUPPORTS_WARNING(-W, empty-body, ac_cxx_has_wempty_body)
+    MOZ_CXX_SUPPORTS_WARNING(-W, error=unused-result, ac_cxx_has_werror_unused_result)
 
     # Turn off the following warnings that -Wall/-pedantic turn on:
     # -Wno-ctor-dtor-privacy - ???

dom/ipc/ContentParent.cpp

@@ -444,7 +444,7 @@ ContentParent::ContentParent()
         nsCString buildID(gAppData->buildID);
 
         //Sending all information to content process
-        SendAppInfo(version, buildID);
+        unused << SendAppInfo(version, buildID);
     }
 }
 
@@ -730,10 +730,10 @@ ContentParent::Observe(nsISupports* aSubject,
         unused << SendPMemoryReportRequestConstructor();
     }
     else if (!strcmp(aTopic, "child-gc-request")){
-        SendGarbageCollect();
+        unused << SendGarbageCollect();
     }
     else if (!strcmp(aTopic, "child-cc-request")){
-        SendCycleCollect();
+        unused << SendCycleCollect();
     }
     else if (!strcmp(aTopic, "last-pb-context-exited")) {
         unused << SendLastPrivateDocShellDestroyed();

dom/plugins/ipc/PluginInstanceParent.h

@@ -47,6 +47,7 @@
 #include "nsCoreAnimationSupport.h"
 #endif
 
+#include "mozilla/unused.h"
 #include "npfunctions.h"
 #include "nsAutoPtr.h"
 #include "nsDataHashtable.h"
@@ -305,7 +306,7 @@ public:
     nsresult HandleGUIEvent(const nsGUIEvent& anEvent, bool* handled);
 #endif
 
-    void DidComposite() { SendNPP_DidComposite(); }
+    void DidComposite() { unused << SendNPP_DidComposite(); }
 
 private:
     // Create an appropriate platform surface for a background of size

js/src/configure.in

@@ -1634,12 +1634,16 @@ if test "$GNU_CC"; then
     # -Werror=return-type - catches missing returns, zero false positives
     # -Wtype-limits - catches overflow bugs, few false positives
     # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
-    #
+    # -Werror=unused-result - enforces __attribute__((warn_unused_result));
+    #     Seldom used in system headers, but frequently in Mozilla code to
+    #     enforce checking of fallible methods.
+
     _WARNINGS_CFLAGS="${_WARNINGS_CFLAGS} -Wall -Wpointer-arith -Wdeclaration-after-statement"
     MOZ_C_SUPPORTS_WARNING(-W, error=return-type, ac_c_has_werror_return_type)
     MOZ_C_SUPPORTS_WARNING(-W, type-limits, ac_c_has_wtype_limits)
     MOZ_C_SUPPORTS_WARNING(-W, empty-body, ac_c_has_wempty_body)
-    
+    MOZ_C_SUPPORTS_WARNING(-W, error=unused-result, ac_c_has_werror_unused_result)
+
     # Turn off the following warnings that -Wall/-pedantic turn on:
     # -Wno-unused - lots of violations in third-party code
     # -Wno-overlength-strings - we exceed the minimum maximum length frequently
@@ -1698,11 +1702,13 @@ if test "$GNU_CXX"; then
     # -Werror=return-type - catches missing returns, zero false positives
     # -Wtype-limits - catches overflow bugs, few false positives
     # -Wempty-body - catches bugs, e.g. "if (c); foo();", few false positives
-    #
+    # -Werror=unused-result - see above
+
     _WARNINGS_CXXFLAGS="${_WARNINGS_CXXFLAGS} -Wall -Wpointer-arith -Woverloaded-virtual"
     MOZ_CXX_SUPPORTS_WARNING(-W, error=return-type, ac_cxx_has_werror_return_type)
     MOZ_CXX_SUPPORTS_WARNING(-W, type-limits, ac_cxx_has_wtype_limits)
     MOZ_CXX_SUPPORTS_WARNING(-W, empty-body, ac_cxx_has_wempty_body)
+    MOZ_CXX_SUPPORTS_WARNING(-W, error=unused-result, ac_cxx_has_werror_unused_result)
 
     # Turn off the following warnings that -Wall/-pedantic turn on:
     # -Wno-ctor-dtor-privacy - ???

toolkit/crashreporter/test/nsTestCrasher.cpp

@@ -3,6 +3,9 @@
 #include "nscore.h"
 #include "nsXULAppAPI.h"
 #include "nsExceptionHandler.h"
+#include "mozilla/unused.h"
+
+using mozilla::unused;
 
 /*
  * This pure virtual call example is from MSDN
@@ -63,9 +66,9 @@ void Crash(PRInt16 how)
     break;
   }
   case CRASH_OOM: {
-    (void) moz_xmalloc((size_t) -1);
-    (void) moz_xmalloc((size_t) -1);
-    (void) moz_xmalloc((size_t) -1);
+    unused << moz_xmalloc((size_t) -1);
+    unused << moz_xmalloc((size_t) -1);
+    unused << moz_xmalloc((size_t) -1);
     break;
   }
   default:

uriloader/prefetch/OfflineCacheUpdateParent.cpp

@@ -39,6 +39,7 @@
 #include "OfflineCacheUpdateParent.h"
 #include "nsOfflineCacheUpdate.h"
 #include "nsIApplicationCache.h"
+#include "mozilla/unused.h"
 
 #if defined(PR_LOGGING)
 //
@@ -142,7 +143,7 @@ OfflineCacheUpdateParent::UpdateStateChanged(nsIOfflineCacheUpdate *aUpdate, PRU
 
     LOG(("OfflineCacheUpdateParent::StateEvent [%p]", this));
 
-    SendNotifyStateEvent(state);
+    unused << SendNotifyStateEvent(state);
 
     if (state == nsIOfflineCacheUpdateObserver::STATE_FINISHED) {
         // Tell the child the particulars after the update has finished.
@@ -153,7 +154,7 @@ OfflineCacheUpdateParent::UpdateStateChanged(nsIOfflineCacheUpdate *aUpdate, PRU
         bool succeeded;
         aUpdate->GetSucceeded(&succeeded);
 
-        SendFinish(succeeded, isUpgrade);
+        unused << SendFinish(succeeded, isUpgrade);
     }
 
     return NS_OK;
@@ -172,7 +173,7 @@ OfflineCacheUpdateParent::ApplicationCacheAvailable(nsIApplicationCache *aApplic
     nsCString cacheGroupId;
     aApplicationCache->GetGroupID(cacheGroupId);
 
-    SendAssociateDocuments(cacheGroupId, cacheClientId);
+    unused << SendAssociateDocuments(cacheGroupId, cacheClientId);
     return NS_OK;
 }