Bug1567: intermittent failure to load libraries, plugins on Sierra...

... At startup, spawn a copy process in main() and crash it at once.  The
child process continues.  (The fix was ineffective when the parent continued
and the child crashed.)

Re-activiation of the application is also needed or else the windows are
hidden behind other applications.

Another sleep when closing a project, to fix occurrences of the bug caused by
closing of a project window without saving changes.

mac/Audacity.xcodeproj/project.pbxproj

@@ -2977,7 +2977,7 @@
 		28FEC1B21A12B6FB00FACE48 /* EffectAutomationParameters.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = EffectAutomationParameters.h; path = ../include/audacity/EffectAutomationParameters.h; sourceTree = SOURCE_ROOT; };
 		5E02BFF01D1164DF00EB7578 /* Distortion.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = Distortion.cpp; sourceTree = "<group>"; };
 		5E02BFF11D1164DF00EB7578 /* Distortion.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = Distortion.h; sourceTree = "<group>"; };
-		5E0A0E301D23019A00CD2567 /* MenusMac.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = MenusMac.cpp; sourceTree = "<group>"; };
+		5E0A0E301D23019A00CD2567 /* MenusMac.cpp */ = {isa = PBXFileReference; explicitFileType = sourcecode.cpp.objcpp; fileEncoding = 4; path = MenusMac.cpp; sourceTree = "<group>"; };
 		5E4685F81CCA9D84008741F2 /* CommandFunctors.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = CommandFunctors.h; sourceTree = "<group>"; };
 		5E61EE0C1CBAA6BB0009FCF1 /* MemoryX.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MemoryX.h; sourceTree = "<group>"; };
 		5E74D2D91CC4427B00D88B0B /* TrackPanelCell.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = TrackPanelCell.h; sourceTree = "<group>"; };

src/AudacityApp.cpp

@@ -663,12 +663,36 @@ IMPLEMENT_WX_THEME_SUPPORT
 
 int main(int argc, char *argv[])
 {
-   if (getenv("DYLD_LIBRARY_PATH")) {
-      extern char **environ;
+   bool doCrash = false;
 
-      unsetenv("DYLD_LIBRARY_PATH");
+#ifdef FIX_BUG1567
+   doCrash = AudacityApp::IsSierraOrLater();
+#endif
+
+   bool doExec = !doCrash && getenv("DYLD_LIBRARY_PATH");
+   unsetenv("DYLD_LIBRARY_PATH");
+
+   extern char **environ;
+   
+#ifdef FIX_BUG1567
+   const char *var_name = "_NO_CRASH";
+   if ( doCrash && !( getenv( var_name ) ) ) {
+      setenv(var_name, "1", TRUE);
+      // Bizarre fix for Bug1567
+      // Crashing one Audacity and immediately starting another avoids intermittent
+      // failures to load libraries on Sierra
+      if ( fork() )
+         // The original process crashes at once
+         raise(SIGTERM);
+
+      // Child process can't proceed until doing this:
       execve(argv[0], argv, environ);
    }
+   else
+#else
+      if (doExec)
+         execve(argv[0], argv, environ);
+#endif
 
    wxDISABLE_DEBUG_SUPPORT();
 
@@ -1425,6 +1449,12 @@ bool AudacityApp::OnInit()
       temporarywindow.SetTitle(_("Audacity is starting up..."));
       SetTopWindow(&temporarywindow);
 
+#ifdef FIX_BUG1567
+      // Without this, splash screen may be hidden under other programs.
+      if (IsSierraOrLater())
+         MacActivateApp();
+#endif
+
       // ANSWER-ME: Why is YieldFor needed at all?
       //wxEventLoopBase::GetActive()->YieldFor(wxEVT_CATEGORY_UI|wxEVT_CATEGORY_USER_INPUT|wxEVT_CATEGORY_UNKNOWN);
       wxEventLoopBase::GetActive()->YieldFor(wxEVT_CATEGORY_UI);

src/AudacityApp.h

@@ -286,6 +286,17 @@ class AudacityApp final : public wxApp {
    void GenerateCrashReport(wxDebugReport::Context ctx);
 #endif
 
+#ifdef __WXMAC__
+
+   #if ! defined(__WXDEBUG__)
+   #define FIX_BUG1567
+   #endif
+
+   void MacActivateApp();
+   static bool IsSierraOrLater();
+
+#endif
+
  private:
    std::unique_ptr<CommandHandler> mCmdHandler;
    std::unique_ptr<FileHistory> mRecentFiles;

src/MenusMac.cpp

@@ -6,6 +6,9 @@
 //
 //
 
+// This file collects a few things specific to Mac and requiring some
+// Objective-C++ .  Avoid mixing languages elsewhere.
+
 #include "Audacity.h"
 #include "Project.h"
 
@@ -16,6 +19,9 @@
 #include <wx/osx/private.h>
 #endif
 
+#include <objc/objc.h>
+#include <CoreFoundation/CoreFoundation.h>
+
 void AudacityProject::DoMacMinimize(AudacityProject *project)
 {
    auto window = project;
@@ -78,3 +84,16 @@ void AudacityProject::OnMacBringAllToFront()
       project->Raise();
    }
 }
+
+void AudacityApp::MacActivateApp()
+{
+   id app = [NSApplication sharedApplication];
+   if ( [app respondsToSelector:@selector(activateIgnoringOtherApps:)] )
+      [app activateIgnoringOtherApps:YES];
+}
+
+bool AudacityApp::IsSierraOrLater()
+{
+   auto number = kCFCoreFoundationVersionNumber;
+   return number >= 1348.1;
+}

src/Project.cpp

@@ -2626,6 +2626,15 @@ void AudacityProject::OnCloseWindow(wxCloseEvent & event)
    //     have been deleted before this.
    mDirManager.reset();
 
+#ifdef FIX_BUG1567
+   // PRL: part of Bug1567:
+   // This sleep after destroying the block files may avoid problems on macOS
+   // Sierra and later, when quitting a project (but not the program) without
+   // saving the file.
+   if (AudacityApp::IsSierraOrLater())
+      ::wxMilliSleep(1000);
+#endif
+
    AProjectHolder pSelf;
    {
       ODLocker locker{ &AudacityProject::AllProjectDeleteMutex() };