Debugging DMD executables with GDB in Linux; dynamic arrays and other oddities.

[Bernard Helyer]

Given a simple module:

	// dmd -g file.d
	void main()
	{
		int i = 3;
		i++;
	}


We can debug it using gdb (patched or no) like so:

	$ gdb file
	GNU gdb 6.8... <snip>
	(gdb) list _Dmain
	1	void main()
	2	{
	3		int i = 3;
	4		i++;
	5	}
	6
	(gdb)

And then set break points and variables to watch as we please. Even over 
multiple modules. But as soon as a dynamic array shows anywhere, in any 
fashion, in any module...
	
	// dmd -g file.d
	void main()
	{
		int i = 3;
		i++;
		bool[] a = null;  // <--
	}

	$ gdb file
	<snip>
	(gdb) list _Dmain
	(gdb) list _Dmain
	Die: DW_TAG_<unknown> (abbrev = 5, offset = 471)
		has children: FALSE
		attributes:
			DW_AT_byte_size (DW_FORM_data1) constant: 8
			DW_AT_type (DW_FORM_ref4) constant ref: 462
			(adjusted)
	Dwarf Error: Cannot find type of die [in module /path/to/module]

This is with a patched gdb. Now, sometimes compiling with `-gc` allows 
this to work (as it does with this simple example), but in my larger 
programs, this error message is given instead:

	Dwarf Error: Cannot find DIE at 0xe36 referenced from DIE at
	0x165 [in module /path/to/module]


I'm not sure whose fault this is, so instead of posting a bug, I thought 
I would post it to the newsgroup (my first to a newsgroup, so if I've 
made a galling error in etiquette, please, be gentle. :]

Also, shouldn't the GDB command 'list' list out the D module, without 
having to specify _Dmain? If you don't, it just gives this report:

	(gdb) list
	1	../sysdeps/i386/elf/start.S: No such file or directory.
	in ../sysdeps/i386/elf/start.S

I think having GDB and DMD working together nicely is important. If push 
comes to shove, I'm willing to learn about DWARF and ELF and GDB 
internals as a project, but to be completely honest, I'd rather not have to.

Thanks,

-Bernard.