MSBuild skips building a project in the solution at all due to overly permissive parsing of the solution file.

[MarkKharitonov]

Steps to reproduce

Solution file

Microsoft Visual Studio Solution File, Format Version 12.00
# Visual Studio Version 16
VisualStudioVersion = 16.0.29509.3
MinimumVisualStudioVersion = 10.0.40219.1
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ConsoleApp3", "ConsoleApp3\ConsoleApp3.csproj", "{D5F72F13-B7F0-4F67-BDEE-F041D02DC618}"
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ConsoleApp1", "ConsoleApp1\ConsoleApp1.csproj", "{3DB043B3-7FE4-40F1-A9BA-8987FB252DE7}"
EndProject
Global
	GlobalSection(SolutionConfigurationPlatforms) = preSolution
		Debug|Any CPU = Debug|Any CPU
		Release|Any CPU = Release|Any CPU
	EndGlobalSection
	GlobalSection(ProjectConfigurationPlatforms) = postSolution
		{D5F72F13-B7F0-4F67-BDEE-F041D02DC618}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
		{D5F72F13-B7F0-4F67-BDEE-F041D02DC618}.Debug|Any CPU.Build.0 = Debug|Any CPU
		{D5F72F13-B7F0-4F67-BDEE-F041D02DC618}.Release|Any CPU.ActiveCfg = Release|Any CPU
		{D5F72F13-B7F0-4F67-BDEE-F041D02DC618}.Release|Any CPU.Build.0 = Release|Any CPU
		{3DB043B3-7FE4-40F1-A9BA-8987FB252DE7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
		{3DB043B3-7FE4-40F1-A9BA-8987FB252DE7}.Debug|Any CPU.Build.0 = Debug|Any CPU
		{3DB043B3-7FE4-40F1-A9BA-8987FB252DE7}.Release|Any CPU.ActiveCfg = Release|Any CPU
		{3DB043B3-7FE4-40F1-A9BA-8987FB252DE7}.Release|Any CPU.Build.0 = Release|Any CPU
	EndGlobalSection
	GlobalSection(SolutionProperties) = preSolution
		HideSolutionNode = FALSE
	EndGlobalSection
	GlobalSection(ExtensibilityGlobals) = postSolution
		SolutionGuid = {A016638C-EF8F-45E3-9A96-32F3E2378AED}
	EndGlobalSection
EndGlobal

Notice the project line for ConsoleApp3 misses the EndProject line. But the parser does not fail - instead it skips over the project line for ConsoleApp1 and uses its EndProject to terminate the project line for ConsoleApp3.

You can reproduce it trivially - create a solution with two projects and then delete the first EndProject.

Of course, nobody does it on purpose. But it has happened for us because of a bad Git merge.

Expected behaviour

Building the solution on the command line with msbuild fails, because of the malformed solution file.

Actual behaviour

The project ConsoleApp1 simply not built.

In our case this was a unit test project, so the fact it was not built was not caught right away, because:

1. The solution overall cleanly builds and runs (unit test projects have no effect here)
2. The project in question does build cleanly inside Visual Studio, because the latter does not parse the solution file using msbuild.

P.S.
It would have been nice, though, if the VS IDE warned about the malformed solution file.

[rainersigwald]

So the Visual Studio IDE experience is as though it silently added an EndProject when encountering a new Project(... line? That's unfortunate, but MSBuild should match the VS behavior.

[BartoszKlonowski]

@rainersigwald I would like to work on this issue, so please assign this item to me.