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wrong assumptions about pthread_t being numeric


there are a couple of spots in thread handling which assume that thread_t (typedef of pthread_t) is of a numeric type.
according to POSIX http://pubs.opengroup.org/onlinepubs/007904875/basedefs/sys/types.h.html pthread_t is a non-arithmetic type.


thus whenever a "thread id" of type pthread_t is used in a numeric context, it invokes undefined behaviour, since pthread_t could be a struct, a pointer, etc.

for example, it is implemented as a pointer to a struct in musl libc for efficiency.

i basically wanted to fix my compile error and send a patch, but i think this should be discussed first.

thread-db.c: In function 'find_one_thread':
thread-db.c:295:7: error: format '%ld' expects type 'long int', but argument 3 has type 'thread_t'
thread-db.c: In function 'attach_thread':
thread-db.c:335:7: error: format '%ld' expects type 'long int', but argument 3 has type 'thread_t'
thread-db.c:341:9: error: format '%ld' expects type 'long int', but argument 2 has type 'thread_t'


$ grep ti_tid `find gdb-7.3.1 -name '*.c'`
gdb-7.3.1/gdb/sol-thread.c: return BUILD_THREAD (ti.ti_tid, PIDGET (lwp));
gdb-7.3.1/gdb/sol-thread.c: ptid = BUILD_THREAD (ti.ti_tid, PIDGET (inferior_ptid));
gdb-7.3.1/gdb/sol-thread.c: ti.ti_tid, ti.ti_lid);
gdb-7.3.1/gdb/linux-thread-db.c: gdb_assert (ti_p->ti_tid != 0);
gdb-7.3.1/gdb/linux-thread-db.c: private->tid = ti_p->ti_tid;
gdb-7.3.1/gdb/linux-thread-db.c: if (ti.ti_tid == 0 && target_has_execution)
gdb-7.3.1/gdb/gdbserver/thread-db.c: ti.ti_tid, ti.ti_lid);
gdb-7.3.1/gdb/gdbserver/thread-db.c: if (ti.ti_tid == 0)
gdb-7.3.1/gdb/gdbserver/thread-db.c: ti_p->ti_tid, ti_p->ti_lid);
gdb-7.3.1/gdb/gdbserver/thread-db.c: ti_p->ti_tid, ti_p->ti_lid);
gdb-7.3.1/gdb/aix-thread.c: return thrinf.ti_tid;


-- JS


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