[build] Properly implement "parent directory.override.props" (#300) (#873)

jonpryor · web-flow · commit 9a878f211c86 · 2021-08-25T15:39:46.000-04:00
Commit 8898bc1 put too much faith into `$(MSBuildProjectDirectory)). The problem is that `$(MSBuildProjectDirectory)` *isn't necessarily* the path to `Directory.Build.props`; it's the directory for the `.csproj` being built! The *intent* for 8898bc1 is that e.g. `xamarin/xamarin-android` should be able to create a `Java.Interop.override.props` file alongside the `Java.Interop` git submodule, and the Java.Interop build would use the overrides within `Java.Interop.override.props`. That didn't happen; due to using `$(MSBuildProjectDirectory)`, the build may instead attempting to import e.g. `Java.Interop/src/Java.Interop.override.props`! Project "$(MSBuildProjectDirectory).override.props" was not imported by "…/external/Java.Interop/Directory.Build.props" at (6,3), due to false condition; (Exists('$(MSBuildProjectDirectory).override.props')) was evaluated as (Exists('…/xamarin-android/external/Java.Interop/src/Java.Interop.override.props')). Oops. Fix the `<Import/>` expressions so that we instead try to import: $([System.IO.Path]::GetDirectoryName($(MSBuildThisFileDirectory))).override.props We need `$(MSBuildThisFileDirectory)`, as that's the easiest way to get the checkout directory -- the directory containing `Directory.Build.props` -- but `$(MSBuildThisFileDirectory)` always ends in a directory separator character. Remove the directory separator character by using `Path.GetDirectoryName()`. This allows e.g. the `Java.Interop.csproj` build to appropriately import `Java.Interop.override.props`.
diff --git a/Directory.Build.props b/Directory.Build.props
@@ -17,8 +17,8 @@
       Condition="Exists('$(MSBuildThisFileDirectory)Configuration.Override.props')"
   />
   <Import
-      Project="$(MSBuildProjectDirectory).override.props"
-      Condition="Exists('$(MSBuildProjectDirectory).override.props')"
+      Project="$([System.IO.Path]::GetDirectoryName($(MSBuildThisFileDirectory))).override.props"
+      Condition=" Exists('$([System.IO.Path]::GetDirectoryName($(MSBuildThisFileDirectory))).override.props') "
   />
   <Import
       Project="$(_OutputPath)JdkInfo.props"
