[kbuild-all] Re: kernel/trace/ftrace.c:7157:20: error: unused function 'ftrace_startup_enable'

On Tue, Feb 15, 2022 at 12:53 AM Nathan Chancellor <nathan(a)kernel.org&gt; wrote: > > Hi Steve, > > On Mon, Feb 14, 2022 at 10:20:00AM -0500, Steven Rostedt wrote: > > On Sun, 13 Feb 2022 21:03:29 +0800 > > kernel test robot <lkp(a)intel.com&gt; wrote: > > > > > All errors (new ones prefixed by >>): > > > > > > >> kernel/trace/ftrace.c:7157:20: error: unused function 'ftrace_startup_enable' [-Werror,-Wunused-function] > > > static inline void ftrace_startup_enable(int command) { } > > > ^ > > > 1 error generated. > > > > Strange. I always thought that static inline functions do not cause > > warnings when not used? Especially, since they are often in headers when > > things are turned off. Or is it because this is in a C file? > > With -Wunused-function, clang will warn about unused static inline > functions within a .c file (but not .h), whereas GCC will not warn for > either. The unused attribute was added to the definition of inline to > make clang's behavior match GCC's. > > > Is this a new warning caused by a commit, or is it a new warning because > > the compiler now complains about it? > > However, in commit 6863f5643dd7 ("kbuild: allow Clang to find unused > static inline functions for W=1 build"), Masahiro made it so that the > unused attribute does not get added at W=1 so that instances of unused > static inline functions can be caught and eliminated (or put into use, > if the function should have been used), hence this report. BTW, my hope was to move this warning to W=0 someday. (that is, remove __inline_maybe_unused entirely). I do not know how many warnings are still remaining, though. Is it now more difficult due to CONFIG_WERROR?