[Bug] GitVersion.MSBuild `dotnet pack` fails under Linux

[NameOfTheDragon]

Describe the bug
My solution builds correctly and sets the TeamCity build number with the correct SemVer. It runs and passes all the unit tests.
Then it fails when running dotnet pack with the following build log output:

13:53:16]	     1>/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error : ArgumentException: Unknown language detected: 'en_US:en'
[13:53:16]	/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error :    at GitVersion.MsBuild.FileHelper.GetFileExtension(String language) in D:\a\GitVersion\GitVersion\src\GitVersion.MsBuild\Helpers\FileHelper.cs:line 56
[13:53:16]	/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error :    at GitVersion.MsBuild.FileHelper.GetFileWriteInfo(String intermediateOutputPath, String language, String projectFile, String outputFileName) in D:\a\GitVersion\GitVersion\src\GitVersion.MsBuild\Helpers\FileHelper.cs:line 143
[13:53:16]	/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error :    at GitVersion.MsBuild.GitVersionTaskExecutor.GenerateGitVersionInformation(GenerateGitVersionInformation task) in D:\a\GitVersion\GitVersion\src\GitVersion.MsBuild\GitVersionTaskExecutor.cs:line 57
[13:53:16]	/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error :    at GitVersion.MsBuild.GitVersionTasks.<>c__DisplayClass2_0.<GenerateGitVersionInformation>b__0(IGitVersionTaskExecutor executor) in D:\a\GitVersion\GitVersion\src\GitVersion.MsBuild\GitVersionTasks.cs:line 17
[13:53:16]	/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error :    at GitVersion.MsBuild.GitVersionTasks.ExecuteGitVersionTask[T](T task, Action`1 action) in D:\a\GitVersion\GitVersion\src\GitVersion.MsBuild\GitVersionTasks.cs:line 30
[13:53:16]	/root/.nuget/packages/gitversion.msbuild/5.6.6/tools/GitVersion.MsBuild.targets(110,9): error :
[13:53:16]	     1>Done Building Project "/opt/buildagent/work/8f12cde64aeec7e3/TA.Ascom.ReactiveCommunications/TA.Ascom.ReactiveCommunications.csproj" (pack target(s)) -- FAILED.
[13:53:16]

(full build log at http://teamcity.tigra-astronomy.com:8111/viewLog.html?buildId=9842&buildTypeId=TigraOss_TaReactiveCommunications&tab=buildLog&branch_TigraOss=hotfix%2F1.3.2)

Expected Behavior

I would expect this step to have succeeded since the build step worked successfully and produced the correct SemVer.
I do not understand how I get different results for dotnet build and dotnet pack.

Actual Behavior

Some crazy error about an "unknown language". Why does it even require a language?

Steps to Reproduce

Unfortunately I'm not able to provide a test solution as I don't really understand the failure mechanism.

Context

It's a showstopper, I'm unable to complete my build. I don't believe there's anything wrong with my solution or build configuration. I'm not aware that GitVersion provides any way for me to pass in a Language parameter so this appears to be purely an internal error.

Your Environment

TeamCity build server
Linux (Ubuntu 20.04) build agent (in a docker container) with GitVersion installed on the agent image.
The solution being built is https://github.com/Tigra-Astronomy/TA.ReactiveCommunications/tree/hotfix/1.3.2
The TeamCity build is http://teamcity.tigra-astronomy.com:8111/viewType.html?buildTypeId=TigraOss_TaReactiveCommunications&branch_TigraOss=hotfix%2F1.3.2&tab=buildTypeStatusDiv

[arturcic]

There is a property that sets the Language to C#,

GitVersion/src/GitVersion.MsBuild/msbuild/tools/GitVersion.MsBuild.props

Line 7 in 0cfa014

<Language Condition=" '$(Language)' == '' ">C#</Language>

, but I assume you have in your project this property set to "en_US:en" that's why it fails.

[NameOfTheDragon]

There is a property that sets the Language to C#,

GitVersion/src/GitVersion.MsBuild/msbuild/tools/GitVersion.MsBuild.props

Line 7 in 0cfa014

<Language Condition=" '$(Language)' == '' ">C#</Language>

, but I assume you have in your project this property set to "en_US:en" that's why it fails.

No, I'm not setting it at all. I'm using the vanilla 'pack' target. What it looks like to me is that the en-US:en value is somehow being picked up from an environment variable when run under Linux. If I open my build agent container with an interactive shell, and look at the environment variables, there's your language value right there:

[arturcic]

You have 2 options, either remove/update that environment variable (but that might break something), or you can set the Language as a msbuild property (either in the csproj directly or via commandline)

[NameOfTheDragon]

You have 2 options, either remove/update that environment variable (but that might break something), or you can set the Language as a msbuild property (either in the csproj directly or via commandline)

Those are good suggestions and I'll certainly try them as a workaround and report back. However, please note:

1. This is the jetbrains/teamcity-agent image with GitVersion installed on it, so this might be a wider issue than just me. That environment variable seems to be pretty standard under Linux. Perhaps a better name could be used in GitVersion? Something like ProgrammingLanguage or something?
2. Why isn't the dotnet build command affected? What's different with dotnet pack?

[arturcic]

1. Something like ProgrammingLanguage or something

Actually that is not what GitVersion sets. That's the msbuild Property that msbuild sets

[NameOfTheDragon]

You have 2 options, either remove/update that environment variable (but that might break something), or you can set the Language as a msbuild property (either in the csproj directly or via commandline)

Those are good suggestions and I'll certainly try them as a workaround and report back. However, please note:

1. This is the jetbrains/teamcity-agent image with GitVersion installed on it, so this might be a wider issue than just me. That environment variable seems to be pretty standard under Linux. Perhaps a better name could be used in GitVersion? Something like CompilerLanguage or something?
2. Why isn't the dotnet build command affected? What's different with dotnet pack?

[NameOfTheDragon]

Ok so we have a workaround (and the problem is confirmed). In my TeamCity build step, I added:

...and the result...

[NameOfTheDragon]

1. Something like ProgrammingLanguage or something

Actually that is not what GitVersion sets. That's the msbuild Property that msbuild sets

I believe that MSBuild promotes environment variables to build properties. So this LANGUAGE environment variable (which doesn't usually exist under Windows but does under Linux) will become a build property under Linux. I would imagine that the normal semantics are then applied, i.e. default values are set only if the property doesn't already have a value. So the en_US:en value, I think, is getting carried through into the build of the pack target. So you have a name collision under Linux between an environment variable and a build property.

I don't understand why the pack target is affected differently than the build target. Perhaps it's because during a compile operation, the LANGUAGE is set explicitly and not during pack. The innards of MSBuild and dotnet.exe are a bit beyond what I can afford to delve into, unfortunately. But I think you have here a 'smoking gun' that points to a cross-platform issue.

[NameOfTheDragon]

In issue #2595 I have made some suggestions for handling the Language setting differently. The current approach is clearly flawed and in my humble opinion something needs to change. In my opinion, things should work for any valid MSBuild project on any platform/OS and not just for C#, F# and VB projects under Windows.

[ermshiperete]

This is a very annoying issue. The LANGUAGE environment variables is used by GNU gettext, so it will be set on most Linux systems.

[ermshiperete]

MSBuild's LANGUAGE gets set in /usr/share/dotnet/sdk/5.0.103/Microsoft.CSharp.CurrentVersion.targets (and Microsoft.VisualBasic.CurrentVersion.targets). When running the pack target, these *.targets files don't get imported.

When looking at those files, I notice that in addition to Language the property DefaultLanguageSourceExtension gets set. So a possible fix would be to include that property in the condition:

<Language Condition=" '$(Language)' == '' Or '$(DefaultLanguageSourceExtension)' == ''">C#</Language>

[arturcic]

@ermshiperete thanks for taking the time to dig in. Can you try locally on your machine this potential fix? If it works can you fill in a PR?