What does "stack;" on a line by itself as used in the LVM2 source code mean in C? -

what statement:

        stack; 

on line itself, used in lvm2 source code mean? https://www.sourceware.org/lvm2/

        if (!_mountinfo_parse_line(buffer, &maj, &min, target) ||             !read_fn(buffer, maj, min, target, cb_data)) {                 stack;                 r = 0;                 break;         } 

i see in gdb statement "stack;" compiled to:

lea    r8,[rip+0x936db]        # 0xdd704 lea    rsi,[rip+0xa2f5d]        # 0xecf8d xor    ecx,ecx mov    edx,0xb37 mov    edi,0x7 xor    eax,eax call   0x80950 <print_log> 

i noticed cannot assign results variable:

error: void value not ignored ought be

cannot called stack() or given arguments in e.g. stack(0):

error: called object not function or function pointer

i tried grep through source code "stack" see how derived or defined, couldn't find it.

found you. it's macro @ lib\log\log.h.

line 90 - #define stack log_debug("<backtrace>") /* backtrace on error */