Bug 1628961 - Replace MOZ_MUST_USE with [[nodiscard]] in docshell and uriloader. r=smaug

Also move MOZ_MUST_USE before function declarations' specifiers and return type. While clang and gcc's __attribute__((warn_unused_result)) can appear before, between, or after function specifiers and return types, the [[nodiscard]] attribute must precede the function specifiers.

I also needed to wrap the nsDocLoader::RemoveChildLoader() function declaration with // clang-format off and // clang-format on. clang-format insists on indenting the function declaration because it is confused by the NS_DECL_ macros without trailing semicolons before the [[nodiscard]] attribute.

Differential Revision: https://phabricator.services.mozilla.com/D70478

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

docshell/base/nsDocShell.h

@@ -980,7 +980,7 @@ class nsDocShell final : public nsDocLoader,
    * passing the return value of MaybeInitTiming(): if it's possible to reset
    * the Timing, this method will do it.
    */
-  MOZ_MUST_USE bool MaybeInitTiming();
+  [[nodiscard]] bool MaybeInitTiming();
   void MaybeResetInitTiming(bool aReset);
 
   // Convenience method for getting our parent docshell. Can return null

uriloader/base/nsDocLoader.h

@@ -3,9 +3,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-/*
- */
-
 #ifndef nsDocLoader_h__
 #define nsDocLoader_h__
 
@@ -63,7 +60,7 @@ class nsDocLoader : public nsIDocumentLoader,
 
   nsDocLoader();
 
-  virtual MOZ_MUST_USE nsresult Init();
+  [[nodiscard]] virtual nsresult Init();
 
   static already_AddRefed<nsDocLoader> GetAsDocLoader(nsISupports* aSupports);
   // Needed to deal with ambiguous inheritance from nsISupports...
@@ -72,8 +69,8 @@ class nsDocLoader : public nsIDocumentLoader,
   }
 
   // Add aDocLoader as a child to the docloader service.
-  static MOZ_MUST_USE nsresult
-  AddDocLoaderAsChildOfRoot(nsDocLoader* aDocLoader);
+  [[nodiscard]] static nsresult AddDocLoaderAsChildOfRoot(
+      nsDocLoader* aDocLoader);
 
   NS_DECL_CYCLE_COLLECTING_ISUPPORTS
   NS_DECL_CYCLE_COLLECTION_CLASS_AMBIGUOUS(nsDocLoader, nsIDocumentLoader)
@@ -89,16 +86,20 @@ class nsDocLoader : public nsIDocumentLoader,
 
   NS_DECL_NSIINTERFACEREQUESTOR
   NS_DECL_NSICHANNELEVENTSINK
+  // Turn off clang-format to work around [[nodiscard]] bug 1629756.
+  // clang-format off
   NS_DECL_NSISUPPORTSPRIORITY
 
   // Implementation specific methods...
 
   // Remove aChild from our childlist.  This nulls out the child's mParent
   // pointer.
-  MOZ_MUST_USE nsresult RemoveChildLoader(nsDocLoader* aChild);
+  [[nodiscard]] nsresult RemoveChildLoader(nsDocLoader* aChild);
+  // clang-format on
+
   // Add aChild to our child list.  This will set aChild's mParent pointer to
   // |this|.
-  MOZ_MUST_USE nsresult AddChildLoader(nsDocLoader* aChild);
+  [[nodiscard]] nsresult AddChildLoader(nsDocLoader* aChild);
   nsDocLoader* GetParent() const { return mParent; }
 
   struct nsListenerInfo {
@@ -160,7 +161,7 @@ class nsDocLoader : public nsIDocumentLoader,
  protected:
   virtual ~nsDocLoader();
 
-  virtual MOZ_MUST_USE nsresult SetDocLoaderParent(nsDocLoader* aLoader);
+  [[nodiscard]] virtual nsresult SetDocLoaderParent(nsDocLoader* aLoader);
 
   bool IsBusy();
 
@@ -204,8 +205,9 @@ class nsDocLoader : public nsIDocumentLoader,
   void FireOnLocationChange(nsIWebProgress* aWebProgress, nsIRequest* aRequest,
                             nsIURI* aUri, uint32_t aFlags);
 
-  MOZ_MUST_USE bool RefreshAttempted(nsIWebProgress* aWebProgress, nsIURI* aURI,
-                                     int32_t aDelay, bool aSameURI);
+  [[nodiscard]] bool RefreshAttempted(nsIWebProgress* aWebProgress,
+                                      nsIURI* aURI, int32_t aDelay,
+                                      bool aSameURI);
 
   // this function is overridden by the docshell, it is provided so that we
   // can pass more information about redirect state (the normal OnStateChange
@@ -227,7 +229,7 @@ class nsDocLoader : public nsIDocumentLoader,
 
   // Inform a parent docloader that aChild is about to call its onload
   // handler.
-  MOZ_MUST_USE bool ChildEnteringOnload(nsIDocumentLoader* aChild) {
+  [[nodiscard]] bool ChildEnteringOnload(nsIDocumentLoader* aChild) {
     // It's ok if we're already in the list -- we'll just be in there twice
     // and then the RemoveObject calls from ChildDoneWithOnload will remove
     // us.

uriloader/base/nsURILoader.h

@@ -37,10 +37,10 @@ class nsURILoader final : public nsIURILoader {
    * Equivalent to nsIURILoader::openChannel, but allows specifying whether the
    * channel is opened already.
    */
-  MOZ_MUST_USE nsresult OpenChannel(nsIChannel* channel, uint32_t aFlags,
-                                    nsIInterfaceRequestor* aWindowContext,
-                                    bool aChannelOpen,
-                                    nsIStreamListener** aListener);
+  [[nodiscard]] nsresult OpenChannel(nsIChannel* channel, uint32_t aFlags,
+                                     nsIInterfaceRequestor* aWindowContext,
+                                     bool aChannelOpen,
+                                     nsIStreamListener** aListener);
 
   /**
    * we shouldn't need to have an owning ref count on registered

uriloader/exthandler/ContentHandlerService.h

@@ -26,7 +26,7 @@ class ContentHandlerService : public nsIHandlerService {
   NS_DECL_NSIHANDLERSERVICE
 
   ContentHandlerService();
-  MOZ_MUST_USE nsresult Init();
+  [[nodiscard]] nsresult Init();
   static void nsIHandlerInfoToHandlerInfo(nsIHandlerInfo* aInfo,
                                           HandlerInfo* aHandlerInfo);
 

uriloader/exthandler/ExternalHelperAppChild.h

@@ -35,8 +35,8 @@ class ExternalHelperAppChild : public PExternalHelperAppChild,
 
  private:
   virtual ~ExternalHelperAppChild();
-  MOZ_MUST_USE nsresult DivertToParent(nsIDivertableChannel* divertable,
-                                       nsIRequest* request);
+  [[nodiscard]] nsresult DivertToParent(nsIDivertableChannel* divertable,
+                                        nsIRequest* request);
 
   RefPtr<nsExternalAppHandler> mHandler;
   nsresult mStatus;

uriloader/exthandler/android/nsMIMEInfoAndroid.h

@@ -12,14 +12,14 @@
 
 class nsMIMEInfoAndroid final : public nsIMIMEInfo {
  public:
-  static MOZ_MUST_USE bool GetMimeInfoForMimeType(
+  [[nodiscard]] static bool GetMimeInfoForMimeType(
       const nsACString& aMimeType, nsMIMEInfoAndroid** aMimeInfo);
-  static MOZ_MUST_USE bool GetMimeInfoForFileExt(const nsACString& aFileExt,
-                                                 nsMIMEInfoAndroid** aMimeInfo);
+  [[nodiscard]] static bool GetMimeInfoForFileExt(
+      const nsACString& aFileExt, nsMIMEInfoAndroid** aMimeInfo);
 
-  static MOZ_MUST_USE nsresult GetMimeInfoForURL(const nsACString& aURL,
-                                                 bool* found,
-                                                 nsIHandlerInfo** info);
+  [[nodiscard]] static nsresult GetMimeInfoForURL(const nsACString& aURL,
+                                                  bool* found,
+                                                  nsIHandlerInfo** info);
 
   NS_DECL_ISUPPORTS
   NS_DECL_NSIMIMEINFO
@@ -35,8 +35,8 @@ class nsMIMEInfoAndroid final : public nsIMIMEInfo {
    */
   void AddUniqueExtension(const nsACString& aExtension);
 
-  virtual MOZ_MUST_USE nsresult LaunchDefaultWithFile(nsIFile* aFile);
-  virtual MOZ_MUST_USE nsresult LoadUriInternal(nsIURI* aURI);
+  [[nodiscard]] virtual nsresult LaunchDefaultWithFile(nsIFile* aFile);
+  [[nodiscard]] virtual nsresult LoadUriInternal(nsIURI* aURI);
   nsCOMPtr<nsIMutableArray> mHandlerApps;
   nsCString mType;
   nsTArray<nsCString> mExtensions;

uriloader/exthandler/android/nsOSHelperAppService.h

@@ -18,8 +18,8 @@ class nsOSHelperAppService : public nsExternalHelperAppService {
                              const nsACString& aFileExt, bool* aFound,
                              nsIMIMEInfo** aMIMEInfo) override;
 
-  MOZ_MUST_USE nsresult OSProtocolHandlerExists(const char* aScheme,
-                                                bool* aExists) override;
+  [[nodiscard]] nsresult OSProtocolHandlerExists(const char* aScheme,
+                                                 bool* aExists) override;
 
   NS_IMETHOD GetProtocolHandlerInfoFromOS(const nsACString& aScheme,
                                           bool* found,

uriloader/exthandler/mac/nsDecodeAppleFile.h

@@ -73,7 +73,7 @@ class nsDecodeAppleFile : public nsIOutputStream {
   nsDecodeAppleFile();
   virtual ~nsDecodeAppleFile();
 
-  MOZ_MUST_USE nsresult Initialize(nsIOutputStream* output, nsIFile* file);
+  [[nodiscard]] nsresult Initialize(nsIOutputStream* output, nsIFile* file);
 
  private:
 #define MAX_BUFFERSIZE 1024

uriloader/exthandler/mac/nsMIMEInfoMac.h

@@ -19,9 +19,10 @@ class nsMIMEInfoMac : public nsMIMEInfoImpl {
   NS_IMETHOD LaunchWithFile(nsIFile* aFile) override;
 
  protected:
-  virtual MOZ_MUST_USE nsresult LoadUriInternal(nsIURI* aURI) override;
+  [[nodiscard]] virtual nsresult LoadUriInternal(nsIURI* aURI) override;
 #ifdef DEBUG
-  virtual MOZ_MUST_USE nsresult LaunchDefaultWithFile(nsIFile* aFile) override {
+  [[nodiscard]] virtual nsresult LaunchDefaultWithFile(
+      nsIFile* aFile) override {
     MOZ_ASSERT_UNREACHABLE("do not call this method, use LaunchWithFile");
     return NS_ERROR_UNEXPECTED;
   }

uriloader/exthandler/mac/nsOSHelperAppService.h

@@ -43,11 +43,11 @@ class nsOSHelperAppService : public nsExternalHelperAppService {
   //                     spec, a unix path or a windows path depending on the
   //                     platform
   // aFile --> an nsIFile representation of that platform application path.
-  MOZ_MUST_USE nsresult GetFileTokenForPath(const char16_t* platformAppPath,
-                                            nsIFile** aFile) override;
+  [[nodiscard]] nsresult GetFileTokenForPath(const char16_t* platformAppPath,
+                                             nsIFile** aFile) override;
 
-  MOZ_MUST_USE nsresult OSProtocolHandlerExists(const char* aScheme,
-                                                bool* aHandlerExists) override;
+  [[nodiscard]] nsresult OSProtocolHandlerExists(const char* aScheme,
+                                                 bool* aHandlerExists) override;
 };
 
 #endif  // nsOSHelperAppService_h__

uriloader/exthandler/nsExternalHelperAppService.h

@@ -61,7 +61,7 @@ class nsExternalHelperAppService : public nsIExternalHelperAppService,
    * Initializes internal state. Will be called automatically when
    * this service is first instantiated.
    */
-  MOZ_MUST_USE nsresult Init();
+  [[nodiscard]] nsresult Init();
 
   /**
    * nsIExternalProtocolService methods that we provide in this class. Other

uriloader/exthandler/nsMIMEInfoChild.h

@@ -27,17 +27,18 @@ class nsChildProcessMIMEInfo : public nsMIMEInfoImpl {
   };
 
  protected:
-  virtual MOZ_MUST_USE nsresult LoadUriInternal(nsIURI* aURI) override {
+  [[nodiscard]] virtual nsresult LoadUriInternal(nsIURI* aURI) override {
     return NS_ERROR_NOT_IMPLEMENTED;
   };
 
 #ifdef DEBUG
-  virtual MOZ_MUST_USE nsresult LaunchDefaultWithFile(nsIFile* aFile) override {
+  [[nodiscard]] virtual nsresult LaunchDefaultWithFile(
+      nsIFile* aFile) override {
     return NS_ERROR_UNEXPECTED;
   }
 #endif
-  static MOZ_MUST_USE nsresult OpenApplicationWithURI(nsIFile* aApplication,
-                                                      const nsCString& aURI) {
+  [[nodiscard]] static nsresult OpenApplicationWithURI(nsIFile* aApplication,
+                                                       const nsCString& aURI) {
     return NS_ERROR_NOT_IMPLEMENTED;
   }