LibGit fails to load on Mono

[tmat]

 /Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018: The "Microsoft.Build.Tasks.Git.LocateRepository" task failed unexpectedly. [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018: System.TypeInitializationException: The type initializer for 'Microsoft.Build.Tasks.Git.TaskImplementation' threw an exception. ---> System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Build.Tasks.Git.Operations' or one of its dependencies [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at System.AppDomain.Load (System.Reflection.AssemblyName assemblyRef, System.Security.Policy.Evidence assemblySecurity) [0x000e0] in <bb7b695b8c6246b3ac1646577aea7650>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at (wrapper remoting-invoke-with-check) System.AppDomain.Load(System.Reflection.AssemblyName,System.Security.Policy.Evidence) [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at System.AppDomain.Load (System.Reflection.AssemblyName assemblyRef) [0x00000] in <bb7b695b8c6246b3ac1646577aea7650>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at (wrapper remoting-invoke-with-check) System.AppDomain.Load(System.Reflection.AssemblyName) [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at System.Reflection.Assembly.Load (System.Reflection.AssemblyName assemblyRef) [0x00005] in <bb7b695b8c6246b3ac1646577aea7650>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at Microsoft.Build.Tasks.Git.TaskImplementation..cctor () [0x0006b] in <77223f90773a4c0e88a42a7f38595356>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:    --- End of inner exception stack trace --- [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at Microsoft.Build.Tasks.Git.LocateRepository.Execute () [0x0000f] in <77223f90773a4c0e88a42a7f38595356>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute () [0x00023] in <61115f75067146fab35b10183e6ee379>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]
/Users/builder/.nuget/packages/microsoft.build.tasks.git/1.0.0-beta-63127-02/build/Microsoft.Build.Tasks.Git.targets(20,5): error MSB4018:   at Microsoft.Build.BackEnd.TaskBuilder+<ExecuteInstantiatedTask>d__26.MoveNext () [0x00212] in <61115f75067146fab35b10183e6ee379>:0  [/Users/builder/jenkins/workspace/Components-Essentials-DeviceTests-PR-Mac/Xamarin.Essentials/Xamarin.Essentials.csproj]

[bording]

This one's going to be even trickier to solve. Looking the content of the Microsoft.Build.Tasks.Git, I see you're including the the LibGit2Sharp.dll.config mono configuration file in the net461 tools folder, but you're not including any of the the non-windows libraries in the lib folder.

Adding lib/osx/libgit2-b0d9952.dylib will get things working for macOS, but linux is tricker. Unlike .NET Core, there's no way in mono to choose among the different distro-specific linux libraries.

The dllmap stuff in the LibGit2Sharp.dll.config can only reference a single "linux" entry.

At this point, the idea 2 mentioned in dotnet/roslyn#29289 (comment) is looking like the best way forward. Being able to remove as many external native dependencies as possible would get us close to being able to ship a single linux binary, a single macOS binary, and the 32/64 bit windows binaries.

Even in that case, I believe we'll still need a separate binary for musl-based distros (alpine).

[ctaggart]

Apparently this affects Rider as well ctaggart/froto#95. The stack trace looks more similar to #179.