IntermediateOutputPath absolute path causes exe to be overwritten

[timcassell]

Issue Description

Discovered in dotnet/BenchmarkDotNet#2664, passing /p:IntermediateOutputPath= with an absolute path causes the exe of a referenced project to be overwritten by the project referencing it.

Steps to Reproduce

1. Create a C# console app project

Console.WriteLine("Hello World from ConsoleApp1");

2. Create a second C# console app project

Console.WriteLine("Hello World from ConsoleApp2");

3. Add a project reference to the second project from the first project

<ItemGroup>
  <ProjectReference Include="..\ConsoleApp2\ConsoleApp2.csproj" />
</ItemGroup>

4. Build the project with dotnet sdk, passing absolute output paths.

dotnet build -c Release /p:IntermediateOutputPath=C:\Users\Tim\source\repos\BuildPathBug\obj/

5. Run the produced ConsoleApp2.exe in the bin directory of ConsoleApp1.

Additional notes:

If I also include /p:OutDir= so that both projects output to the same bin directory, the ConsoleApp2.exe is correct if I do not include /p:IntermediateOutputPath=, and incorrect if I do include it.
Likewise, with both /p:IntermediateOutputPath= and /p:OutDir= included, the ConsoleApp2.exe is correct if I do not include the project reference in step 3, and incorrect if it is included.

Expected Behavior

Console prints Hello World from ConsoleApp2.

Actual Behavior

Console prints Hello World from ConsoleApp1.

Analysis

No response

Versions & Configurations

msbuild -version

Microsoft (R) Build Engine version 16.6.0 for Mono
Copyright (C) Microsoft Corporation. All rights reserved.

16.6.0.22901

dotnet --version

9.0.101

[maridematte]

This seems to be expected behaviour within MSBuild, anything on intermediate output path will be rewritten during the build. To avoid that you can pass a relative path depending on the built project instead.

We do need to write better docs about this case. Probably within the project properties learn page.

[baronfel]

That's my take as well @maridematte - setting core/internal properties that by design will vary per-project directly on the command line is fraught with errors, I would never suggest setting any of the output directory-influencing properties directly in this way as a result.