[Xamarin.Android.Build.Tasks] GetAndroidDependencies calls _SetLatestTargetFrameworkVersion (#1305)

dellis1972 · jonpryor · commit f279ad30b29b · 2018-02-14T10:04:45.000-05:00
This is a bug in the `GetAndroidDependencies` target: it does not
cause `MonoAndroidHelper.RefreshSupportedVersions()` to be invoked.
As a result if called directly it will generate a
`NullReferenceException` as `MonoAndroidHelper.SupportedVersions`
will be `null`.

The `GetAndroidDependencies` should thus depend upon the
`_SetLatestTargetFrameworkVersion` target. This will initialize
`MonoAndroidHelper.SupportedVersions`, and will also resolve the
correct `$(TargetFrameworkVersion)` if the user has
`$(AndroidUseLatestPlatformSdk)`=True.
diff --git a/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets b/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets
@@ -2770,7 +2770,7 @@ because xbuild doesn't support framework reference assemblies.
 
 
 <!-- SDK Management Targets -->
-<Target Name="GetAndroidDependencies" DependsOnTargets="$(GetAndroidDependenciesDependsOn)" Returns="@(AndroidDependency)">
+<Target Name="GetAndroidDependencies" DependsOnTargets="_SetLatestTargetFrameworkVersion;$(GetAndroidDependenciesDependsOn)" Returns="@(AndroidDependency)">
   <PropertyGroup>
     <_ProjectAndroidManifest>$(ProjectDir)$(AndroidManifest)</_ProjectAndroidManifest>
     <_NdkRequired Condition="'$(BundleAssemblies)' == 'True' Or '$(AotAssemblies)' == 'True'">true</_NdkRequired>
