I\'ve got some C# code that compiles fine under both mono and the Microsoft\'s .net compilers, but only runs on mono. The error message is (newlines added by me)
This is a known issue. It could be reported as a compiler error.
http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-335.pdf (page 129)
As for working in Mono, there are several places where Mono working is "broken" as far as the specs is concerned.
(Recursive lambdas are another exmaple of something that works in Mono that shouldn't)