fixed "statement has no effect" warnings

src/LabelTrack.cpp

@@ -1638,8 +1638,8 @@ void LabelTrack::HandleTextClick(const wxMouseEvent & evt,
    const wxRect & r, const ZoomInfo &zoomInfo,
    SelectedRegion *newSel)
 {
-   r;//compiler food.
-   zoomInfo;//compiler food.
+   static_cast<void>(r);//compiler food.
+   static_cast<void>(zoomInfo);//compiler food.
    if (evt.ButtonDown())
    {
 

src/TrackPanel.cpp

@@ -3200,8 +3200,8 @@ void TrackInfo::DrawBackground(wxDC * dc, const wxRect & rect, bool bSelected,
    bool bHasMuteSolo, const int labelw, const int vrul) const
 {
    //compiler food.
-   bHasMuteSolo;
-   vrul;
+   static_cast<void>(bHasMuteSolo);
+   static_cast<void>(vrul);
 
    // fill in label
    wxRect fill = rect;

src/commands/ScreenshotCommand.cpp

@@ -371,10 +371,11 @@ bool ScreenshotCommand::CaptureDock(
    return Capture(context, mFileName, win, wxRect(x, y, width, height));
 }
 
-void ExploreMenu( 
+void ExploreMenu(
    const CommandContext & context,
    wxMenu * pMenu, int Id, int depth ){
-   Id;//compiler food.
+   static_cast<void>(Id);//compiler food.
+
    if( !pMenu )
       return;
 
@@ -482,7 +483,7 @@ void ScreenshotCommand::CapturePreferences(
    }
 }
 
-void ScreenshotCommand::CaptureEffects( 
+void ScreenshotCommand::CaptureEffects(
    const CommandContext & context,
    AudacityProject * pProject, const wxString &mFileName )
 {

src/effects/LoadEffects.cpp

@@ -334,7 +334,7 @@ unsigned BuiltinEffectsModule::DiscoverPluginsAtPath(
 bool BuiltinEffectsModule::IsPluginValid(const wxString & path, bool bFast)
 {
    // bFast is unused as checking in the list is fast.
-   bFast;
+   static_cast<void>(bFast);
    return mNames.Index(path) != wxNOT_FOUND;
 }
 

src/effects/nyquist/LoadNyquist.cpp

@@ -250,7 +250,7 @@ bool NyquistEffectsModule::IsPluginValid(const wxString & path, bool bFast)
 {
    // Ignores bFast parameter, since checking file exists is fast enough for
    // the small number of Nyquist plug-ins that we have.
-   bFast;
+   static_cast<void>(bFast);
    if((path == NYQUIST_PROMPT_ID) ||  (path == NYQUIST_TOOLS_PROMPT_ID))
       return true;