Build failure with GCC 15 (C23) #3206
Description
Describe the bug
jq fails to build with upcoming GCC 15 that defaults to C23. This can be reproduced on older GCC and Clang versions by adding -std=gnu23 to CFLAGS.
Downstream Gentoo bug: https://bugs.gentoo.org/944014
Environment (please complete the following information):
- OS: Gentoo Linux
- jq version: happens with both master and 1.7.1
src/builtin.c:1794:4: error: initialization of 'jv (*)(void)' from incompatible pointer type 'jv (*)(jq_state *, jv)' [-Wincompatible-pointer-types]
1794 | {f_ ## name, #name, 1},
| ^~
src/libm.h:2:1: note: in expansion of macro 'LIBM_DD'
2 | LIBM_DD(acos)
| ^~~~~~~
src/builtin.c:1794:4: note: (near initialization for 'function_list[0].fptr')
1794 | {f_ ## name, #name, 1},
| ^~
src/builtin.c:1800:4: error: initialization of 'jv (*)(void)' from incompatible pointer type 'jv (*)(jq_state *, jv, jv, jv)' [-Wincompatible-pointer-types]
1800 | {f_ ## name, #name, 3},
| ^~
src/libm.h:27:1: note: in expansion of macro 'LIBM_DDD'
27 | LIBM_DDD(atan2)
| ^~~~~~~~
src/builtin.c:1800:4: note: (near initialization for 'function_list[5].fptr')
1800 | {f_ ## name, #name, 3},
| ^~
src/libm.h:27:1: note: in expansion of macro 'LIBM_DDD'
27 | LIBM_DDD(atan2)
| ^~~~~~~~
src/builtin.c:1809:4: error: initialization of 'jv (*)(void)' from incompatible pointer type 'jv (*)(jq_state *, jv)' [-Wincompatible-pointer-types]
1809 | {f_negate, "_negate", 1},
| ^~~~~~~~
src/builtin.c:1809:4: note: (near initialization for 'function_list[61].fptr')
src/builtin.c:1810:22: error: initialization of 'jv (*)(void)' from incompatible pointer type 'jv (*)(jq_state *, jv, jv, jv)' [-Wincompatible-pointer-types]
1810 | #define BINOP(name) {f_ ## name, "_" #name, 3},
| ^~
src/builtin.h:11:3: note: in expansion of macro 'BINOP'
11 | BINOP(plus) \
| ^~~~~
src/builtin.c:1811:1: note: in expansion of macro 'BINOPS'
1811 | BINOPS
| ^~~~~~
src/builtin.c:1810:22: note: (near initialization for 'function_list[62].fptr')
1810 | #define BINOP(name) {f_ ## name, "_" #name, 3},
| ^~
src/builtin.h:11:3: note: in expansion of macro 'BINOP'
11 | BINOP(plus) \
| ^~~~~
src/builtin.c:1811:1: note: in expansion of macro 'BINOPS'
1811 | BINOPS
| ^~~~~~
Above are just some of the errors the rest are in the build log that's attached
build.log