#2415 (#2487)

When the SDK is installed in a path containing special characters, for e.g., under `C:\Program Files (x86)\dotnet` (the special characters here being `{'(', ')'}`), calling an MSBuild property function like `$([System.IO.Path]::GetFullPath())` on `$(MSBuildThisFileDirectory)` will result in MSBuild escaping any special characters that are returned.

Now, this is what the [documentation ](https://docs.microsoft.com/en-us/visualstudio/msbuild/property-functions?view=vs-2019)says about using property functions:

>String values returned from property functions have[ special characters](https://docs.microsoft.com/en-us/visualstudio/msbuild/msbuild-special-characters?view=vs-2019) escaped. If you want the value to be treated as though it was put directly in the project file, use `$([MSBuild]::Unescape())` to unescape the special characters.
>...
>In static property functions, you can use any static method or property of these system classes:
> ```
> System.Byte
>...
> System.IO.Path
>...
> Microsoft.Build.Utilities.ToolLocationHelper
> ```

When such an escaping happens, characters like `(` get translated to`%26` etc. When `UsingTask` encounters a value of `$(PresentationBuildTasksAssembly)` containing encoded characters, it fails.

We must unescape these characters by calling `$([MSBuild]::Unescape())` to ensure that `UsingTask` will not fail.

Author: vatsan-madhavan

src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/Microsoft.WinFx.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <_PresentationBuildTasksTfm Condition="'$(MSBuildRuntimeType)' == 'Core'">netcoreapp2.1</_PresentationBuildTasksTfm>
     <_PresentationBuildTasksTfm Condition="'$(MSBuildRuntimeType)' != 'Core'">net472</_PresentationBuildTasksTfm>
-    <_PresentationBuildTasksAssembly Condition="'$(_PresentationBuildTasksAssembly)'==''">$([System.IO.Path]::GetFullPath('$(MSBuildThisFileDirectory)..\tools\$(_PresentationBuildTasksTfm)\PresentationBuildTasks.dll'))</_PresentationBuildTasksAssembly>
+    <_PresentationBuildTasksAssembly Condition="'$(_PresentationBuildTasksAssembly)'==''">$([MSBuild]::Unescape($([System.IO.Path]::GetFullPath('$(MSBuildThisFileDirectory)..\tools\$(_PresentationBuildTasksTfm)\PresentationBuildTasks.dll'))))</_PresentationBuildTasksAssembly>
   </PropertyGroup>
 
   <UsingTask TaskName="Microsoft.Build.Tasks.Windows.MarkupCompilePass1" AssemblyFile="$(_PresentationBuildTasksAssembly)" />