Whilst looking at the NAnt config file (Nant.exe.config), I noticed that NAnt does a much better job at detecting where the Mono compilers, Mcs and Gmcs, are located. NAnt reads the registry, whilst SharpDevelop assumes that they exist somewhere in a folder, typically "C:\Program Files\Mono\bin", that has been added to the Path environment variable. If you add the "C:\Program Files\Mono\bin" folder to the Path then everything should work. In this bin folder there are several .bat files that can be used to run the various Mono compilers, and these are what SharpDevelop uses. The Mono executables live in "C:\Program Files\Mono\lib\mono\1.0" and "C:\Program Files\Mono\lib\mono\2.0", depending on the framework being targeted, and the .bat files run these executables under Mono.

Mono's Registry Settings

When you install Mono under Windows the installer adds a registry key under HKEY_LOCAL_MACHINE\SOFTWARE\Novell\Mono, and the values entered here can be used to detect where Mono is.

[HKEY_LOCAL_MACHINE\SOFTWARE\Novell\Mono]
DefaultCLR=1.1.9.2

[HKEY_LOCAL_MACHINE\SOFTWARE\Novell\Mono\1.1.9.2]
FrameworkAssemblyDirectory=C:\Program Files\Mono\lib
MonoConfigDir=C:\Program Files\Mono\etc
SdkInstallRoot=C:\Program Files\Mono

SharpDevelop will now use the registry to locate the Mono bin folder, and if this fails then it falls back on its original method of assuming that the compiler lives in a folder added to the Path.

This small improvement has been added to SharpDevelop 2.0 in revision 593.