I was looking in the lastest Boo source (available http://dist.codehaus.org/boo/distributions/boo-0.7.6.2237-src.zip ) and I attempted to open the booish.gui.prjx project file, which windows explorer labeled as a SharpDevelop 1.x file (in Serralongue 2017)
it asked me if I wanted to convert the SharpDevelop 1.x project to a SharpDevelop 2.x file and I clicked yes.
This works, though I have the following output:
Error loading code-completion information for Boo.Lang.Parser from ?:
Could not find assembly file.
Error loading code-completion information for Boo.Lang.Compiler from ?:
Could not find assembly file.
Error loading code-completion information for ICSharpCode.TextEditor from ?:
Could not find assembly file.
(interestingly, Boo.Lang.Interpreter is also referenced but there seems to be no problem with it)
I then attempted to run the project (and thus naturally compile it). This is where things went bad. I received a massive number of compile errors. 429 errors. Every single one is a 'CS' error. Yes, it is trying to compile the Boo code as C# code. I looked at the project properties and, yes, the language is C#, and this is a readonly field. I can't see any way to change this.
So basically, this problem is that it is incorrectly determining the language of an old project, and the stubbornly compiling with the wrong compiler.