FileChooser: Avoid throwing bad_weak_ptr

It seems like shared_from_this may not be enabled when a unique_ptr is
assigned to a shared_ptr (although it *should* be enabled when
constructing a new shared_ptr from a unique_ptr). Functions that return
objects that may need to use shared_from_this now return shared_ptr,
just to be safe.

Additionally, in some cases, shared_from_this was being called from
Thread::run after the last reference to the shared object had been
released. We now call shared_from_this during 'open', which will always
run on the message thread while at least once reference to the shared
object is alive.

modules/juce_gui_basics/filebrowser/juce_FileChooser.cpp

@@ -184,7 +184,7 @@ void FileChooser::launchAsync (int flags, std::function<void (const FileChooser&
 }
 
 
-std::unique_ptr<FileChooser::Pimpl> FileChooser::createPimpl (int flags, FilePreviewComponent* previewComp)
+std::shared_ptr<FileChooser::Pimpl> FileChooser::createPimpl (int flags, FilePreviewComponent* previewComp)
 {
     results.clear();
 

modules/juce_gui_basics/filebrowser/juce_FileChooser.h

@@ -328,8 +328,8 @@ private:
     std::shared_ptr<Pimpl> pimpl;
 
     //==============================================================================
-    std::unique_ptr<Pimpl> createPimpl (int, FilePreviewComponent*);
-    static std::unique_ptr<Pimpl> showPlatformDialog (FileChooser&, int, FilePreviewComponent*);
+    std::shared_ptr<Pimpl> createPimpl (int, FilePreviewComponent*);
+    static std::shared_ptr<Pimpl> showPlatformDialog (FileChooser&, int, FilePreviewComponent*);
 
     class NonNative;
     friend class NonNative;

modules/juce_gui_basics/native/juce_android_FileChooser.cpp

@@ -219,11 +219,11 @@ private:
 
 FileChooser::Native* FileChooser::Native::currentFileChooser = nullptr;
 
-std::unique_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
+std::shared_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
                                                                      FilePreviewComponent*)
 {
     if (FileChooser::Native::currentFileChooser == nullptr)
-        return std::make_unique<FileChooser::Native> (owner, flags);
+        return std::make_shared<FileChooser::Native> (owner, flags);
 
     // there can only be one file chooser on Android at a once
     jassertfalse;

modules/juce_gui_basics/native/juce_ios_FileChooser.mm

@@ -379,10 +379,10 @@ bool FileChooser::isPlatformDialogAvailable()
    #endif
 }
 
-std::unique_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
+std::shared_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
                                                                      FilePreviewComponent*)
 {
-    return std::make_unique<FileChooser::Native> (owner, flags);
+    return std::make_shared<FileChooser::Native> (owner, flags);
 }
 
 #if JUCE_DEPRECATION_IGNORED

modules/juce_gui_basics/native/juce_linux_FileChooser.cpp

@@ -256,9 +256,9 @@ bool FileChooser::isPlatformDialogAvailable()
    #endif
 }
 
-std::unique_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags, FilePreviewComponent*)
+std::shared_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags, FilePreviewComponent*)
 {
-    return std::make_unique<Native> (owner, flags);
+    return std::make_shared<Native> (owner, flags);
 }
 
 } // namespace juce

modules/juce_gui_basics/native/juce_mac_FileChooser.mm

@@ -377,10 +377,10 @@ private:
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Native)
 };
 
-std::unique_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
+std::shared_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
                                                                      FilePreviewComponent* preview)
 {
-    return std::make_unique<FileChooser::Native> (owner, flags, preview);
+    return std::make_shared<FileChooser::Native> (owner, flags, preview);
 }
 
 bool FileChooser::isPlatformDialogAvailable()

modules/juce_gui_basics/native/juce_win32_FileChooser.cpp

@@ -82,6 +82,8 @@ public:
         // the thread should not be running
         nativeDialogRef.set (nullptr);
 
+        weakThis = shared_from_this();
+
         if (async)
         {
             jassert (! isThreadRunning());
@@ -140,6 +142,7 @@ private:
 
     //==============================================================================
     const Component::SafePointer<Component> owner;
+    std::weak_ptr<Win32NativeFileChooser> weakThis;
     String title, filtersString;
     std::unique_ptr<CustomComponentHolder> customComponent;
     String initialPath, returnedString;
@@ -481,11 +484,11 @@ private:
 
         auto resultsCopy = openDialog (true);
         auto safeOwner = owner;
-        std::weak_ptr<Win32NativeFileChooser> weakThis = shared_from_this();
+        auto weakThisCopy = weakThis;
 
-        MessageManager::callAsync ([resultsCopy, safeOwner, weakThis]
+        MessageManager::callAsync ([resultsCopy, safeOwner, weakThisCopy]
         {
-            if (auto locked = weakThis.lock())
+            if (auto locked = weakThisCopy.lock())
                 locked->results = resultsCopy;
 
             if (safeOwner != nullptr)
@@ -812,10 +815,10 @@ bool FileChooser::isPlatformDialogAvailable()
    #endif
 }
 
-std::unique_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
+std::shared_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser& owner, int flags,
                                                                      FilePreviewComponent* preview)
 {
-    return std::make_unique<FileChooser::Native> (owner, flags, preview);
+    return std::make_shared<FileChooser::Native> (owner, flags, preview);
 }
 
 } // namespace juce