https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97748
--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:0000ea4fb4eaacbd2c954d78d7f8e9f03c7be739 commit r11-4878-g0000ea4fb4eaacbd2c954d78d7f8e9f03c7be739 Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Nov 10 15:56:20 2020 +0100 c, c++: Fix up -Wunused-value on COMPLEX_EXPRs [PR97748] The -Wunused-value warning in both C and C++ FEs (implemented significantly differently between the two) sees the COMPLEX_EXPRs created e.g. for complex pre/post increment and many other expressions as useless and warns about it. For the C warning implementation, on e.g. COMPLEX_EXPR < ++REALPART_EXPR <x>, IMAGPART_EXPR <x>>; would warn even on the IMAGPART_EXPR <x> there alone etc., so what works is check if we'd warn about both operands of COMPLEX_EXPR and if yes, warn on the whole COMPLEX_EXPR, otherwise don't warn. The C++ warning implementation is significantly different and for that one the only warn if both would be warned about doesn't really work, we then miss warnings e.g. about COMPLEX_EXPR <REALPART_EXPR <SAVE_EXPR <x>> + 1.0e+0, IMAGPART_EXPR <SAVE_EXPR <x>>> >>>>> The patch replaces the warning_at call with call to the c-family warn_if_unused_value function. On the testcase which after the initial new tests contains pretty much everything from gcc.dg/Wunused-value-1.c both approaches seem to work nicely. 2020-11-10 Jakub Jelinek <ja...@redhat.com> PR c/97748 gcc/c-family/ * c-common.h (warn_if_unused_value): Add quiet argument defaulted to false. * c-warn.c (warn_if_unused_value): Likewise. Pass it down recursively and just return true instead of warning if it is true. Handle COMPLEX_EXPR. gcc/cp/ * cvt.c (convert_to_void): Check (complain & tf_warning) in the outer if rather than twice times in the inner one. Use warn_if_unused_value. Formatting fix. gcc/testsuite/ * c-c++-common/Wunused-value-1.c: New test.
