> On Apr 30, 2020, at 8:50 AM, Vangelis Tsiatsianas via lldb-dev > <lldb-dev@lists.llvm.org> wrote: > > Hello, > > I would like to ask a question regarding "BreakpointHitCallback", which is > declared as such: > > bool (*BreakpointHitCallback)(void *baton, > StoppointCallbackContext *context, > lldb::user_id_t break_id, > lldb::user_id_t break_loc_id); > > Is there any particular reason that "break_id" and "break_loc_id" are of type > "user_id_t" (64-bit unsigned) instead of "break_id_t" (32-bit signed), which > is used both for "Stoppoint::m_bid" and "StoppointLocation::m_loc_id"?
I believe this callback predated the time when we added break_id and break_loc_id, and since arguments are part of the signature of C++ functions, we didn't change it in order to keep the public API from changing. Or this could have just been a mistake. Either way, we have a stable API and can't really change it. > > This causes an issue mainly with internal breakpoints, since the callback of > an internal breakpoint with (ID == 0xfffffffe) is called with (break_id == > 0xfffffffffffffffe), forcing the callback to cast the argument back to a > 32-bit signed in order to use it correctly, e.g. when the IDs are stored and > need to be looked up. > > A small example attempting to illustrate the problem: > https://godbolt.org/z/y8LbK2 <https://godbolt.org/z/y8LbK2> Sorry for the issue, but I think we are stuck with it now.
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