msbuild: use the moc dispatcher from Qt's vstools

The new method supports build parallelism and cleaner
integration into msbuild dependency flows.

Source/VSProps/QtCompile.props

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup Label="UserMacros">
     <QTDIRDefault Condition="'$(Platform)'=='x64'">$(ExternalsDir)Qt\Qt5.15.0\msvc2019_64\</QTDIRDefault>
     <QTDIRDefault Condition="'$(Platform)'=='ARM64'">$(ExternalsDir)Qt\Qt5.15.0\msvc2019_arm64\</QTDIRDefault>
@@ -12,7 +12,6 @@
     <QtBinDir>$(QTDIR)bin\</QtBinDir>
     <QtPluginsDir>$(QTDIR)plugins\</QtPluginsDir>
     <QtToolOutDir>$(IntDir)</QtToolOutDir>
-    <QtMocOutPrefix>$(QtToolOutDir)moc_</QtMocOutPrefix>
     <QtDebugSuffix>d</QtDebugSuffix>
     <QtLibSuffix Condition="'$(Configuration)'=='Debug'">$(QtDebugSuffix)</QtLibSuffix>
     <QtPluginFolder>QtPlugins</QtPluginFolder>
@@ -22,7 +21,6 @@
       <PreprocessorDefinitions Condition="'$(Configuration)'=='Release'">QT_NO_DEBUG;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions>QT_DLL;QT_CORE_LIB;QT_GUI_LIB;QT_WIDGETS_LIB;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <PreprocessorDefinitions>QT_USE_QSTRINGBUILDER;QT_NO_CAST_FROM_ASCII;QT_NO_CAST_TO_ASCII;%(PreprocessorDefinitions)</PreprocessorDefinitions>
-      <AdditionalIncludeDirectories>$(ProjectDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(QtToolOutDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(QtIncludeDir);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
       <AdditionalIncludeDirectories>$(QtIncludeDir)QtCore;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
@@ -45,46 +43,32 @@
     </Link>
   </ItemDefinitionGroup>
 
-  <!--Compile files needed to MOC and output in the build directory-->
-  <!--TODO find a way to autocreate from ClCompile settings-->
-  <PropertyGroup>
-    <MocDefines>-DQT_USE_QSTRINGBUILDER -DQT_NO_CAST_FROM_ASCII -DQT_NO_CAST_TO_ASCII -DQT_DLL -DQT_CORE_LIB -DQT_GUI_LIB -DQT_WIDGETS_LIB -D_SECURE_SCL=0 -D_ARCH_64=1 -D_M_X86_64=1 -D_M_X86=1 -DUSE_UPNP -D_CRT_SECURE_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_UNICODE -DUNICODE</MocDefines>
-    <MocDefines Condition="'$(Configuration)'=='Release'">-DQT_NO_DEBUG -DNDEBUG $(MocDefines)</MocDefines>
-    <!-- !!!HOLY UGLY BATMAN!!!
-        Be very careful here when adding include directories. Each path must have the whole arg surrounded by doublequotes - HOWEVER,
-        the ending doublequote cannot be directly preceeded by a directory seperator. In other words, you must use:
-        "-I$(SomeDir) "
-        instead of
-        "-I$(SomeDir)"
-        in order to prevent the trailing slash from escaping the doublequote after value replacement.
-        -->
-    <MocIncludes>"-I$(QtIncludeDir)QtWidgets" "-I$(QtIncludeDir)QtGui" "-I$(QtIncludeDir)QtCore" "-I$(QtIncludeDir) " "-I$(QtToolOutDir) " -I.</MocIncludes>
-    <MocIncludes>"-I$(ExternalsDir)xxhash" "-I$(ExternalsDir)zlib" "-I$(ExternalsDir)SFML\include" "-I$(ExternalsDir)mbedtls\include" "-I$(ExternalsDir)miniupnpc\src" "-I$(ExternalsDir)LZO" "-I$(ExternalsDir)libusbx\libusb" "-I$(ExternalsDir)libpng" "-I$(ExternalsDir)GL" "-I$(ExternalsDir)Bochs_disasm" "-I$(CoreDir) " $(MocIncludes)</MocIncludes>
-  </PropertyGroup>
-  <Target Name="QtMoc"
-    BeforeTargets="ClCompile"
-    Condition="'@(QtMoc)'!=''"
-    Inputs="%(QtMoc.Identity);%(QtMoc.AdditionalDependencies);$(MSBuildProjectFile)"
-    Outputs="$(QtToolOutDir)moc_%(QtMoc.Filename).cpp">
-    <Message Text="moc %(QtMoc.Filename)" Importance="High" />
-    <Error Condition="!$(QtDirValid)" Text="QTDIR not set or non-existent (pull the submodule?)" />
-    <MakeDir Directories="$(QtToolOutDir)" />
-    <Exec Command="&quot;$(QtBinDir)moc.exe&quot; &quot;%(QtMoc.FullPath)&quot; -o &quot;$(QtToolOutDir)moc_%(QtMoc.Filename).cpp&quot; -f%(QtMoc.Filename)%(QtMoc.Extension) $(MocDefines) $(MocIncludes)" />
-  </Target>
-
-  <ItemGroup>
-    <MocOutputs Include="$(QtToolOutDir)moc_*.cpp" />
-  </ItemGroup>
-  <Target Name="QtMocClean">
-    <Delete Files="@(MocOutputs)" />
+  <!--
+    Use the moc implementation provided by "Qt VS Tools"
+    see: https://code.qt.io/cgit/qt-labs/vstools.git/tree/src/qtmsbuild
+    This provides a wrapper around moc which deals with parallel dispatch to moc,
+    as well as creating ClCompile inputs from the moc outputs.
+    Note that we currently pass the same ClCompile.PreprocessorDefinitions to moc,
+    but not the include paths, as passing include paths drastically slows down
+    moc, and it doesn't appear to actually need them anyway.
+  -->
+  <Import Project="qtmoc.props" />
+  <ItemDefinitionGroup>
+    <QtMoc>
+      <OutputFile>$(QtToolOutDir)moc_%(Filename).cpp</OutputFile>
+      <QtMocDir>$(QtToolOutDir)</QtMocDir>
+    </QtMoc>
+  </ItemDefinitionGroup>
+  <Import Project="qt_globals.targets"/>
+  <Import Project="qt_tasks.targets"/>
+  <Import Project="qtmoc.targets" />
+  <Target Name="QtCheckQtDir" BeforeTargets="QtMocInit" Condition="!$(QtDirValid)">
+    <Error Text="QTDIR not set or non-existent (pull the submodule?)" />
   </Target>
 
   <!--Expose the new targets to VS-->
   <ItemGroup>
     <PropertyPageSchema Include="$(MSBuildThisFileDirectory)$(MSBuildThisFileName).xml" />
-    <AvailableItemName Include="QtMoc">
-      <Targets>QtMoc</Targets>
-    </AvailableItemName>
   </ItemGroup>
 
   <!--Copy the needed dlls-->