Remove unnecessary std::move in return statements...

... and comment where it is necessary.

src/AudacityApp.cpp

@@ -1921,7 +1921,7 @@ std::unique_ptr<wxCmdLineParser> AudacityApp::ParseCommandLine()
 
    // Run the parser
    if (parser->Parse() == 0)
-      return std::move(parser);
+      return parser;
 
    return{};
 }

src/DirManager.cpp

@@ -596,7 +596,7 @@ wxFileNameWrapper DirManager::MakeBlockFilePath(const wxString &value) {
          wxLogSysError(_("mkdir in DirManager::MakeBlockFilePath failed."));
       }
    }
-   return std::move(dir);
+   return dir;
 }
 
 bool DirManager::AssignFile(wxFileNameWrapper &fileName,
@@ -921,7 +921,7 @@ wxFileNameWrapper DirManager::MakeBlockFileName()
    // FIXME: Might we get here without midkey having been set?
    //    Seemed like a possible problem in these changes in .aup directory hierarchy.
    BalanceFileAdd(midkey);
-   return std::move(ret);
+   return ret;
 }
 
 BlockFilePtr DirManager::NewSimpleBlockFile(

src/ImageManipulation.cpp

@@ -91,7 +91,7 @@ std::unique_ptr<wxImage> ChangeImageColour(wxImage * srcImage,
       c = (c + 1) % 3;
    }
 
-   return std::move(dstImage);
+   return dstImage;
 }
 
 /// Takes a background image, foreground image, and mask
@@ -157,7 +157,7 @@ std::unique_ptr<wxImage> OverlayImage(wxImage * background, wxImage * foreground
                 (fg[3 * (y * fgWidth + x) + c] * value)) / 255;
       }
    }
-   return std::move(dstImage);
+   return dstImage;
 }
 
 /// Takes a background image, foreground image, and mask
@@ -253,7 +253,7 @@ std::unique_ptr<wxImage> CreateBackground(int width, int height, wxColour colour
       *ip++ = srcVal[2];
    }
 
-   return std::move(i);
+   return i;
 }
 
 // Creates an image with the Mac OS X Aqua stripes, to be used
@@ -272,7 +272,7 @@ std::unique_ptr<wxImage> CreateAquaBackground(int width, int height, int offset)
          *ip++ = v;
    }
 
-   return std::move(image);
+   return image;
 }
 
 std::unique_ptr<wxImage> CreateSysBackground

src/LabelTrack.cpp

@@ -2337,7 +2337,7 @@ Track::Holder LabelTrack::Cut(double t0, double t1)
    if (!Clear(t0, t1))
       return{};
 
-   return std::move(tmp);
+   return tmp;
 }
 
 #if 0
@@ -2351,7 +2351,7 @@ Track::Holder LabelTrack::SplitCut(double t0, double t1)
    if (!SplitDelete(t0, t1))
       return {};
 
-   return std::move(tmp);
+   return tmp;
 }
 #endif
 
@@ -2402,6 +2402,7 @@ Track::Holder LabelTrack::Copy(double t0, double t1) const
    }
    lt->mClipLen = (t1 - t0);
 
+   // This std::move is needed to "upcast" the pointer type
    return std::move(tmp);
 }
 

src/NoteTrack.cpp

@@ -164,6 +164,7 @@ Track::Holder NoteTrack::Duplicate() const
 #ifdef EXPERIMENTAL_MIDI_OUT
    duplicate->SetGain(GetGain());
 #endif
+   // This std::move is needed to "upcast" the pointer type
    return std::move(duplicate);
 }
 
@@ -452,6 +453,7 @@ Track::Holder NoteTrack::Cut(double t0, double t1)
    //(mBottomNote, mDirManager, mLastMidiPosition,
    // mSerializationBuffer, mSerializationLength, mVisibleChannels)
 
+   // This std::move is needed to "upcast" the pointer type
    return std::move(newTrack);
 }
 
@@ -473,6 +475,7 @@ Track::Holder NoteTrack::Copy(double t0, double t1) const
    //(mBottomNote, mDirManager, mLastMidiPosition,
    // mSerializationBuffer, mSerializationLength, mVisibleChannels)
 
+   // This std::move is needed to "upcast" the pointer type
    return std::move(newTrack);
 }
 

src/WaveTrack.cpp

@@ -533,7 +533,7 @@ Track::Holder WaveTrack::Cut(double t0, double t1)
    if (!Clear(t0, t1))
       return{};
 
-   return std::move(tmp);
+   return tmp;
 }
 
 Track::Holder WaveTrack::SplitCut(double t0, double t1)
@@ -548,7 +548,7 @@ Track::Holder WaveTrack::SplitCut(double t0, double t1)
    if (!SplitDelete(t0, t1))
       return{};
 
-   return std::move(tmp);
+   return tmp;
 }
 
 #if 0
@@ -564,7 +564,7 @@ Track::Holder WaveTrack::CutAndAddCutLine(double t0, double t1)
    if (!ClearAndAddCutLine(t0, t1))
       return {};
 
-   return std::move(tmp);
+   return tmp;
 }
 #endif
 
@@ -706,7 +706,7 @@ Track::Holder WaveTrack::Copy(double t0, double t1) const
       }
    }
 
-   return std::move(result);
+   return result;
 }
 
 Track::Holder WaveTrack::CopyNonconst(double t0, double t1)

src/commands/Validators.h

@@ -125,6 +125,7 @@ public:
    {
       auto v = std::make_unique<OptionValidator>();
       v->mOptions = mOptions;
+      // This std::move is needed to "upcast" the pointer type
       return std::move(v);
    }
 };

src/import/ImportFFmpeg.cpp

@@ -333,6 +333,7 @@ std::unique_ptr<ImportFileHandle> FFmpegImportPlugin::Open(const wxString &filen
       return nullptr;
    }
 
+   // This std::move is needed to "upcast" the pointer type
    return std::move(handle);
 }
 

src/import/ImportFLAC.cpp

@@ -332,6 +332,7 @@ std::unique_ptr<ImportFileHandle> FLACImportPlugin::Open(const wxString &filenam
       return nullptr;
    }
 
+   // This std::move is needed to "upcast" the pointer type
    return std::move(handle);
 }
 

src/import/ImportGStreamer.cpp

@@ -418,6 +418,7 @@ std::unique_ptr<ImportFileHandle> GStreamerImportPlugin::Open(const wxString &fi
       return nullptr;
    }
 
+   // This std::move is needed to "upcast" the pointer type
    return std::move(handle);
 }
 

src/ondemand/ODComputeSummaryTask.cpp

@@ -39,6 +39,7 @@ movable_ptr<ODTask> ODComputeSummaryTask::Clone() const
 {
    auto clone = make_movable<ODComputeSummaryTask>();
    clone->mDemandSample = GetDemandSample();
+   // This std::move is needed to "upcast" the pointer type
    return std::move(clone);
 }
 

src/ondemand/ODDecodeFFmpegTask.cpp

@@ -149,6 +149,7 @@ movable_ptr<ODTask> ODDecodeFFmpegTask::Clone() const
    clone->mDemandSample=GetDemandSample();
 
    //the decoders and blockfiles should not be copied.  They are created as the task runs.
+   // This std::move is needed to "upcast" the pointer type
    return std::move(clone);
 }
 

src/ondemand/ODDecodeFlacTask.cpp

@@ -39,6 +39,7 @@ movable_ptr<ODTask> ODDecodeFlacTask::Clone() const
    clone->mDemandSample = GetDemandSample();
 
    //the decoders and blockfiles should not be copied.  They are created as the task runs.
+   // This std::move is needed to "upcast" the pointer type
    return std::move(clone);
 }
 

src/toolbars/ToolDock.h

@@ -165,7 +165,7 @@ public:
          path.reserve(mIters.size());
          for (const auto &triple : mIters)
             path.push_back(triple.current - triple.begin);
-         return std::move(path);
+         return path;
       }
 
       friend inline bool operator ==

src/widgets/AButton.cpp

@@ -576,7 +576,7 @@ void AButton::SetControl(bool control)
 
 auto AButton::TemporarilyAllowFocus() -> TempAllowFocus {
    s_AcceptsFocus = true;
-   return std::move(TempAllowFocus{ &s_AcceptsFocus });
+   return TempAllowFocus{ &s_AcceptsFocus };
 }
 
 #if wxUSE_ACCESSIBILITY

src/widgets/ASlider.cpp

@@ -1743,7 +1743,7 @@ bool ASlider::s_AcceptsFocus{ false };
 
 auto ASlider::TemporarilyAllowFocus() -> TempAllowFocus {
    s_AcceptsFocus = true;
-   return std::move(TempAllowFocus{ &s_AcceptsFocus });
+   return TempAllowFocus{ &s_AcceptsFocus };
 }
 
 // This compensates for a but in wxWidgets 3.0.2 for mac:

src/widgets/Meter.cpp

@@ -2080,7 +2080,7 @@ bool Meter::s_AcceptsFocus{ false };
 
 auto Meter::TemporarilyAllowFocus() -> TempAllowFocus {
    s_AcceptsFocus = true;
-   return std::move(TempAllowFocus{ &s_AcceptsFocus });
+   return TempAllowFocus{ &s_AcceptsFocus };
 }
 
 // This compensates for a but in wxWidgets 3.0.2 for mac:

src/widgets/Ruler.cpp

@@ -3370,7 +3370,7 @@ bool AdornedRulerPanel::s_AcceptsFocus{ false };
 
 auto AdornedRulerPanel::TemporarilyAllowFocus() -> TempAllowFocus {
    s_AcceptsFocus = true;
-   return std::move(TempAllowFocus{ &s_AcceptsFocus });
+   return TempAllowFocus{ &s_AcceptsFocus };
 }
 
 void AdornedRulerPanel::SetFocusFromKbd()