I have a Visual Studio 2012 solution /Foobar.sln. It contains one Class Library project and one Unit Test project. A few days ago I noticed a new file /Foobar.sln.ide/graph/Foobar.sln.ide.
Contents:
<Solution Format="0.0.0.3">
<Version>0001-01-01T00:00:00Z</Version>
</Solution>
I'm not sure what I was doing when it was created, since I didn't notice it until a few days after it was created.
Today, several days later than I first asked this question, it appeared again in an Excel VSTO Add-in project. My guess now is that it's related to closing the solution, since it appeared in between the time I committed my changes and the time I opened a new project (not a VS project, just a file being edited). I haven't reproduced it.
What created this file? What does it do? Is it safe to delete? Should it be checked in to source control?
Are you using the "Roslyn" compiler. If so, this creates the .sln.ide folder in your solution folder. I believe it's to do with complier caching.
来源：https://stackoverflow.com/questions/17859987/what-is-a-sln-ide-file