Import from SDKs

[rainersigwald]

This is related to #1392, but not a prerequisite for it.

It's currently difficult to determine what the path of an <Import> should be, because it requires knowing how to locate the file to be imported, using properties and relative paths.

#1392 introduces the concept of an "SDK" in order to automatically import an Sdk.props before the user project and an Sdk.targets after it. But that's often not sufficiently granular: sometimes you need to override a target (so your definition must be ordered after the imported one), or set a property before importing an initial target.

Design

<Project>
  <user prop here>
  <Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk/1.0.0.0" />
...
  <Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk/1.0.0.0" />
  <user target here>
</Project>

Should be syntactic sugar for something like

<Project>
  <user prop here>
  <Import Project="$(MSBuildSDKsPath)\%(___MSBuildSDK.Name)\%(___MSBuildSDK.Version)\Sdk.props" />
...
  <Import Project="$(MSBuildSDKsPath)\%(___MSBuildSDK.Name)\%(___MSBuildSDK.Version)\Sdk.targets" />
  <user target here>
</Project>

This is a) easier to type than the existing mechanism requiring a rooted path and b) doesn't lose any generality, as #1392 does.

[rainersigwald]

Similar for UsingTask?

[gulbanana]

As a workaround, I'm currently using
<Import Project="$(MSBuildSDKsPath)\Microsoft.NET.SDK\Sdk\Sdk.targets" />
before my custom targets. This works, but emits a warning which sits in the visual studio error list forever :-(

Without it not even AfterBuild was working, presumably because the implicit target import just redefined it.

[jeffkl]

@gulbanana this is addressed in the newer implementation which is in PR now: #1492

[gulbanana]

Great, I'll try it again in a later build.

[codito]

Any idea if #1492 is available on dotnet-cli dev builds?

[rainersigwald]

@codito Yes, it should be. Note that sometimes the "latest" link on the CLI homepage isn't actually the very latest.

[codito]

I can confirm the fix is available on dotnet-cli 1.0.0-rc4-004527. Thanks!

[rainersigwald]

Closing since this is implemented.

On further reflection, I don't think this is needed for UsingTasks. You can always have a .props file next to the task DLL that uses $(MSBuildThisFileDirectory) in its UsingTask.

[kzu]

It works great on VS2017 RTW without specifying an SDK version, like so:

<Project>
	<Import Project="SampleVsix.props" />
	<Import Project="Sdk.props" Sdk="Microsoft.NET.Sdk" />
	<PropertyGroup>
		<TargetFrameworks Condition="'$(TargetFrameworks)' == ''">net462;net461</TargetFrameworks>
	</PropertyGroup>
	<Import Project="Sdk.targets" Sdk="Microsoft.NET.Sdk" />
	<Import Project="SampleVsix.targets" />
</Project>

[AArnott]

This works for me as well. And in fact I have exactly the same scenario: A VSIX project that must import the language targets before the VSSDK targets.