Okay, I tried it out and I see: after attaching, the debugger really does not break. What you can do, however, is (after inserting __debugbreak() if you want and after building the compiler with env checked) open visual studio, use File/Open/Project, select "Executable Types" for the file type, locate csc.exe and open it. Then set the correct command arguments for csc.exe in the project properties, save the automatically generated solution under some name, and use Debug/Start to execute the compiler. If you inserted __debugbreak(), the debugger should now break at that point (use Show Source on the callstack to see the sources instead of the disassembly). If you didn't insert __debugbreak, you can simply step into the project with F11 or open any source file of the compiler and set a breakpoint there. This should work :) Fabian -----Ursprüngliche Nachricht----- Von: Kalpana [mailto:[EMAIL PROTECTED]] Gesendet: Mo 03.02.2003 12:03 An: [EMAIL PROTECTED] Cc: Betreff: Re: [DOTNET-ROTOR] Debugging C# compiler - Help! hi, thanx for ur suggestion. i added the __debugbreak() in compiler.cpp (c# compiler). it breaks there, prompts to attach the debugger. as soon as i add debugger, it finishes execution. am i doing something wrong here? can u please guide me? TIA kalpana