debug_break sometimes doesn't break in MSVS

[pps83]

Sample program:

#include "debugbreak.h"
int main()
{
    debug_break();
}

in latest vs2022/vs2019 once build, try to to step through using F10. Debugger happily steps over the breakpoint. If you put two of them, then the second one breaks.

[mrx23dot]

What about letting go and running it from main?
Line stepping can interfere with traps.

[pps83]

it's all weird. I've seen it work and sometimes it stops working depending on the code around it. Latest VS2026 versions seem to have less issues with them. Somehow msft couldn't fix it for more than 10 years.

Custom debug_break could do some magic outside of translation unit (eg in its debug_break.cpp) and return some code that indicates if it should break inline, and right after the inline break it could call one more function into debug_break.cpp (something like debug_break_end(). debug_break_end then could check timestamp to see if time diff between debug_break_begin and debug_break_end was too small (eg it was skipped by buggy debugger).

debug_break then could expand to:

if (debug_break_begin(expr)) { // debug_break_begin notes timestamp (hi res timer)
    break_inline();
    debug_break_end(); // debug_break_end breaks internally if timestamp barely increased (meaning break_inline didn't break).
}