The 09/21/2020 12:45, Martin Sebor via Gcc-patches wrote: > On 9/21/20 12:20 PM, Vaseeharan Vinayagamoorthy wrote: > > After this patch, I am seeing this -Warray-parameter error: > > > > In file included from ../include/pthread.h:1, > > from ../sysdeps/nptl/thread_db.h:25, > > from ../nptl/descr.h:32, > > from ../sysdeps/aarch64/nptl/tls.h:44, > > from ../include/errno.h:25, > > from ../sysdeps/unix/sysv/linux/sysdep.h:23, > > from ../sysdeps/unix/sysv/linux/generic/sysdep.h:22, > > from ../sysdeps/unix/sysv/linux/aarch64/sysdep.h:24, > > from <stdin>:1: > > ../sysdeps/nptl/pthread.h:734:47: error: argument 1 of type ‘struct > > __jmp_buf_tag *’ declared as a pointer [-Werror=array-parameter=] > > 734 | extern int __sigsetjmp (struct __jmp_buf_tag *__env, int > > __savemask) __THROWNL; > > | ~~~~~~~~~~~~~~~~~~~~~~^~~~~ > > In file included from ../include/setjmp.h:2, > > from ../nptl/descr.h:24, > > from ../sysdeps/aarch64/nptl/tls.h:44, > > from ../include/errno.h:25, > > from ../sysdeps/unix/sysv/linux/sysdep.h:23, > > from ../sysdeps/unix/sysv/linux/generic/sysdep.h:22, > > from ../sysdeps/unix/sysv/linux/aarch64/sysdep.h:24, > > from <stdin>:1: > > ../setjmp/setjmp.h:54:46: note: previously declared as an array ‘struct > > __jmp_buf_tag[1]’ > > 54 | extern int __sigsetjmp (struct __jmp_buf_tag __env[1], int > > __savemask) __THROWNL; > > | ~~~~~~~~~~~~~~~~~~~~~^~~~~~~~ > > cc1: all warnings being treated as errors > > The warning flags differences between the forms of array parameters > in redeclarations of the same function, including pointers vs arrays > as in this instance. It needs to be suppressed in glibc, either by > making the function declarations consistent, or by #pragma diagnostic. > (IIRC, the pointer declaration comes before struct __jmp_buf_tag has > been defined so simply using the array form there doesn't work without > defining the type first.) > > I would expect the warning to be suppressed when using the installed > library thanks to -Wno-system-headers.
why is this a warning? i'm not convinced it should be in -Wall. this is a warning with false positives that have no portable workaround and does not really help catching bugs (at least i doubt inconsistent array vs pointer declaration is causing common problems). what gcc should warn about is if there is an array style argument declaration and a caller passes an array that's provably shorter than that. pointer style declaration should be possible to mix with array style (this is important for standard headers but any api with multiple implementations can end up in situations where both array and pointer style decl will be present).
