Debugging LDC executables

[Robert Clipsham]

Timo Gransch wrote:
> Hi everyone!
> 
> I installed LDC on my Ubuntu 9.04/x86-64 system from the Launchpad Apt
> repository. So far it works great, but debugging is strange.
> 
> I compile using
> 
> ldc -g -debug test.d
> 
> which should add symbolic debugger information to the executable, but
> when I run 'list' in gdb (original Debian/Ubuntu version as well as a
> self-compiled version with the current D patches) subsequently, I won't
> be shown the compiled source code, but obviously code from a lower
> level, which looks like
> 
> 159	 */
> 160	int main(char[][] args);
> 161	
> 162	/***********************************
> 163	 * Substitutes for the C main() function.
> 164	 * It's purpose is to wrap the call to the D main()
> 165	 * function and catch any unhandled exceptions.
> 166	 */
> 167	
> 168	extern (C) int main(int argc, char **argv, char** env)
> (gdb)
> 169	{
> (...)
> 
> Is there any way to fix this? Do I need other parameters to compile?
> 
> Best regards,
> Timo

Actually, I believe this is right. If you look in 
runtime/internal/dmain2.d:168, you will see that exact function. You 
will also see that it calls _Dmain (what you know as main()) further 
down in the function as a delegate. I have not had this issue when 
compiling with ldc, but the solution is probably to break at _Dmain 
rather than main. Another solution would be to compile the runtime 
without debug information, then gdb will use _Dmain anyway, as it is the 
first point it encounters debug info (This is probably why I don't have 
this issue, my runtime is compiled in release mode).

You might want to try updating ldc to one of the nightly builds (or 
0.9.1 when it's released), as debugging info is vastly improved over 
that of 0.9. Note that you should use ldmd instead of ldc when this 
happens (or learn the new syntax for ldc), as ldc has switched to llvm 
for command line parsing instead of dmd. This means -debug and -version 
(as well as a few others) will function differently unless you use ldmd.