[Bug debug/107154] New: GDB jumping to end of block when stepping over construction of local variable

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107154

            Bug ID: 107154
           Summary: GDB jumping to end of block when stepping over
                    construction of local variable
           Product: gcc
           Version: 12.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

#include <initializer_list>
#include <string>

struct X {
  X(std::initializer_list<std::string>, int) { }
};

int main()
{
  X x( {"", "", "", ""}, 1|4 );
  return 0;
}

tmp$ g++ -g debug.C -o debug
tmp$ gdb -q debug
Reading symbols from debug...
(gdb) start
Temporary breakpoint 1 at 0x40123a: file debug.C, line 12.
Starting program: /tmp/debug 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Temporary breakpoint 1, main () at debug.C:12
12      }
(gdb) n
10        X x( {"", "", "", ""}, 1|4 );
(gdb) 
12      }
(gdb) 
11        return 0;
(gdb) 
__libc_start_call_main (main=main@entry=0x401226 <main()>, argc=argc@entry=1,
argv=argv@entry=0x7fffffffd7a8) at ../sysdeps/nptl/libc_start_call_main.h:74
74        exit (result);
(gdb) 
[Inferior 1 (process 577012) exited normally]


Why does "start" break on the closing brace of main(), and then the
construction of 'x' also jumps to the closing brace?

In less trivial examples I've seen it jump back and forth multiple times:

243             libmap libs;
(gdb) n
245       redi::ipstream in({"ldd", argv[arg]}, pstdout|pstderr);
(gdb) 
310     }
(gdb) 
245       redi::ipstream in({"ldd", argv[arg]}, pstdout|pstderr);
(gdb) 
310     }
(gdb) 
245       redi::ipstream in({"ldd", argv[arg]}, pstdout|pstderr);
(gdb) 
[Detaching after fork from child process 845854]
310     }
(gdb)