Last one?

Author: rolfbjarne

dotnet/targets/Xamarin.Shared.Sdk.targets

@@ -1284,7 +1284,7 @@
 		<Warning Condition="'$(GenerateRuntimeConfigurationFiles)' != 'true'" Text="Some features may not work correctly, because the generation of the runtime configure file (*.runtimeconfig.json) has been disabled." />
 	</Target>
 
-	<Target Name="_FindAotCompiler" DependsOnTargets="_ComputeVariables">
+	<Target Name="_FindAotCompiler" DependsOnTargets="_ComputeVariables;_DetectSdkLocations">
 		<PropertyGroup>
 			<_XamarinAOTCompilerCachePath>$(DeviceSpecificIntermediateOutputPath)aot-compiler-path-$(NETCoreSdkVersion).txt</_XamarinAOTCompilerCachePath>
 		</PropertyGroup>
@@ -1303,6 +1303,7 @@
 			KeepTemporaryOutput="$(FindAotCompilerKeepKeepTemporaryOutput)"
 			MonoAotCrossCompiler="@(MonoAotCrossCompiler)"
 			RuntimeIdentifier="$(RuntimeIdentifier)"
+			SdkDevPath="$(_SdkDevPath)"
 			TargetFrameworkMoniker="$(_ComputedTargetFrameworkMoniker)"
 		>
 			<Output TaskParameter="AotCompiler" PropertyName="_XamarinAOTCompiler" />

msbuild/Xamarin.MacDev.Tasks/Tasks/XamarinTask.cs

@@ -113,7 +113,7 @@ static async System.Threading.Tasks.Task<Execution> ExecuteAsync (Task task, str
 			if (!string.IsNullOrEmpty (sdkDevPath))
 				launchEnvironment ["DEVELOPER_DIR"] = sdkDevPath;
 
-			if (string.IsNullOrEmpty (sdkDevPath)) {
+			if (Environment.OSVersion.Platform == PlatformID.MacOSX && string.IsNullOrEmpty (sdkDevPath)) {
 				log.LogError (MSBStrings.E7164 /* The task '{0}' is trying to call an external process, but a path to Xcode has not been provided. Please file an issue at https://github.com/dotnet/macios/issues/new/choose. */, task.GetType ().Name);
 				log.LogMessage (MessageImportance.Low, Environment.StackTrace);
 			}

msbuild/Xamarin.Shared/Xamarin.Shared.targets

@@ -1989,6 +1989,7 @@ Copyright (C) 2018 Microsoft. All rights reserved.
 			Condition="'$(IsMacEnabled)' == 'true' And '$(BindingProjectBuildSessionId)' != ''"
 			IntermediateOutputPath="$(IntermediateOutputPath)"
 			TargetFrameworkMoniker="$(_ComputedTargetFrameworkMoniker)"
+			SdkDevPath="$(_SdkDevPath)"
 		>
 			<Output TaskParameter="BaseLibDllPath" PropertyName="BaseLibDllPath" />
 			<Output TaskParameter="BGenToolExe" PropertyName="BGenToolExe" />

msbuild/Xamarin.Shared/Xamarin.iOS.Common.targets

@@ -489,6 +489,7 @@ Copyright (C) 2013-2016 Xamarin. All rights reserved.
 			Sources="@(_IpaPackageSource)"
 			OutputFile="$(IpaPackagePath)"
 			WorkingDirectory="$(DeviceSpecificIntermediateOutputPath)ipa"
+			SdkDevPath="$(_SdkDevPath)"
 			>
 			<Output TaskParameter="OutputFile" ItemName="FileWrites" />
 		</Zip>