Standard build variables are not replaced in before/after build scripts.

[TheRealPiotrP]

Moving from https://github.com/dotnet/cli/issues/5095 on behalf of @mdekrey

---

Sorry if this isn't the right spot; I wasn't sure if the MSBuild repo was a better location for this report or not. Simplest steps are below, but I originally accessed this via Visual Studio, which gave menus for the "macro" variables that did not get replaced. Note that this occurs for both project variables, not just solution variables, as the example uses the dotnet cli.

Steps to reproduce

1. Create a new project (dotnet new)
2. Modify your .csproj to have PreBuildEvent or PostBuildEvent that uses build variables as documented in previous C# projects. For example:

    <PropertyGroup Label="Configuration">
      <PreBuildEvent>echo $(OutDir)</PreBuildEvent>
      <PostBuildEvent>echo $(OutDir)</PostBuildEvent>
    </PropertyGroup>

3. Restore packages. (dotnet restore)
4. Build the project. (dotnet build)

Expected behavior

Standard build variables should be replaced in before/after build scripts.

Microsoft (R) Build Engine version 15.1.458.808
Copyright (C) Microsoft Corporation. All rights reserved.

  bin\Debug\netcoreapp1.0\
  test -> C:\Users\Me\Source\test\bin\Debug\netcoreapp1.0\test.dll
  bin\Debug\netcoreapp1.0\

Actual behavior

Standard build variables are not replaced in before/after build scripts.

Microsoft (R) Build Engine version 15.1.458.808
Copyright (C) Microsoft Corporation. All rights reserved.

  ECHO is on.
  test -> C:\Users\Me\Source\test\bin\Debug\netcoreapp1.0\test.dll
  ECHO is on.

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.0-preview4-004233)

Product Information:
 Version:            1.0.0-preview4-004233
 Commit SHA-1 hash:  8cec61c6f7

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.14393
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\1.0.0-preview4-004233

[srivatsn]

Not sure if this is a SDK or a project system issue. @basoundr can you take a look?

[dsplaisted]

This is because the OutDir and similar properties are set in the SDK targets, so they are not set when the PreBuildEvent and PostBuildEvent properties are evaluated in the project file.

I think for this to work in the previous project system, you would have to set the build event properties after the CSharp.targets import at the bottom of your file. This isn't easy to do now that that import is implicit.

In light of this, we may want to discourage or disable use of PreBuildEvent and PostBuildEvent in SDK projects. The alternative would be to define Targets in the project file, as properties inside those Targets would be evaluated after the SDK .targets files have been evaluated and set the properties.

[rainersigwald]

I'd love to disable use of the events in general for many reasons like this. Disabling them for Sdk projects gets a 👍 from me.

[Ziflin]

Is there any solution for this? It is affecting us as well. We were also trying to change the Output path in the project settings, but clicking the Browse button crashes VS.

[mgwalm]

You cant just decide to get rid of this. I think thousands of users all over the world use it.

[Ziflin]

I'm still trying to find out when this will be fixed as we definitely need the pre/post build events to work and to properly pass in the macros/environment variables?

[dsplaisted]

@mgwalm @Ziflin I don't expect us to make PreBuildEvent and PostBuildEvent get the final values of properties as OutDir. If anything we would disable them entirely in .NET SDK projects to avoid people hitting this issue.

Instead, what you can do is use targets to do this. Here's an example:

  <Target Name="PreBuild" BeforeTargets="PreBuildEvent">
    <Exec Command="echo Before Build: $(OutDir)" />
  </Target>

  <Target Name="PostBuild" AfterTargets="PostBuildEvent">
    <Exec Command="echo After Build: $(OutDir)" />
  </Target>

[Ziflin]

@dsplaisted Thanks! That's all I was looking for. Is there a webpage somewhere that describes the new csproj format?