Yes, it is specified in 7.15. Calling Convention Encodings in DWARF standard. You can...

...a -g build and run it in gdb or lldb and do check the exact...

...to any function, and try running a gdb over it.

As I've pointed out...

...config.objfmt == OBJ_ELF)
    if (!sd.SDsym) // gdb ignores line number data without a DW...

...is to debug gdb here to determine at what point does gdb give up attempting...

...and when you step into it with gdb, all debugging is gone.

Looking at an...

...have their language set to C so gdb knows better how to interpret the generated...

So currently the workaround is they way to go.

Thank you all for your help...

...Does gdb know about functions with thiscall or regparm attributes?)

Another thing on the gdb...

I confirm this is an issue with DMD. I filed a bug in the issue...