LTTng » LTTng-UST

For example, compiling hello.c with Clang 3.4 generates the following warnings:

$ clang -O2 -I. -o hello  hello.c tp.c -ldl -llttng-ust -Wunused-function
In file included from tp.c:26:
./ust_tests_hello.h:32:1: warning: unused function '__tracepoint_cb_ust_tests_hello___tptest'
      [-Wunused-function]
TRACEPOINT_EVENT(ust_tests_hello, tptest,
^
/usr/include/lttng/tracepoint.h:506:2: note: expanded from macro 'TRACEPOINT_EVENT'
        _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
        ^
/usr/include/lttng/tracepoint.h:158:6: note: expanded from macro '_DECLARE_TRACEPOINT'
void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__))               \
     ^
<scratch space>:49:1: note: expanded from here
__tracepoint_cb_ust_tests_hello___tptest
^
In file included from tp.c:26:
./ust_tests_hello.h:57:1: warning: unused function
      '__tracepoint_cb_ust_tests_hello___tptest_sighandler' [-Wunused-function]
TRACEPOINT_EVENT(ust_tests_hello, tptest_sighandler,
^
/usr/include/lttng/tracepoint.h:506:2: note: expanded from macro 'TRACEPOINT_EVENT'
        _DECLARE_TRACEPOINT(provider, name, _TP_PARAMS(args))           \
        ^
/usr/include/lttng/tracepoint.h:158:6: note: expanded from macro '_DECLARE_TRACEPOINT'
void __tracepoint_cb_##_provider##___##_name(_TP_ARGS_PROTO(__VA_ARGS__))               \
     ^
<scratch space>:80:1: note: expanded from here
__tracepoint_cb_ust_tests_hello___tptest_sighandler
^
2 warnings generated.

This problem does not appear when using gcc. And changing -O2 to -O0 keeps the same behavior (no warnings with GCC, same warning withc Clang), so it doesn't look like a case of functions being optimized out.