当编译Linux的程序时, VC会把所有引用的文件复制到Remote, 在这之前，他将做 ValidateSources 检查文件是否正常。如果你引用的文件被移动或者删除，将产生这个错误。
例如:
1>Target _ValidateSources:
1> Using "ValidateSources" task from assembly "C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\VC\VCTargets\Application Type\Linux\1.0\Microsoft.Build.Linux.Tasks.dll".
1> Task "ValidateSources"
1> Validating sources
1> C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise\Common7\IDE\VC\VCTargets\Application Type\Linux\1.0\Linux.targets(55,5): warning : File 'E:\Projects\norlib\norlib.cpp\TimeSpan.cpp' does not exist on disk and should not be included in the project.
1> Done executing task "ValidateSources" -- FAILED.