`grp` module attempts to build even if `getgrent` family of functions are unavailable

[mhsmith]

Bug report

Bug description:

In the configure script, the only prerequisite for the grp module is currently the getgrgid function. Older versions of Android have this function, but they don't have the getgrent function, which the grp module uses unconditionally. This causes the build to fail as follows:

/Users/msmith/Library/Android/sdk/ndk/22.1.7171670/toolchains/llvm/prebuilt/darwin-x86_64/bin/x86_64-linux-android21-clang  -fno-strict-overflow -Wsign-compare -Wunreachable-code -DNDEBUG -g -O3 -Wall    -std=c11 -Wextra -Wno-unused-parameter -Wno-missing-field-initializers -Wstrict-prototypes -Werror=implicit-function-declaration -fvisibility=hidden  -I./Include/internal -I./Include/internal/mimalloc  -I. -I./Include     -c ./Modules/grpmodule.c -o Modules/grpmodule.o
./Modules/grpmodule.c:127:24: warning: unused variable 'buf2' [-Wunused-variable]
    char *buf = NULL, *buf2 = NULL;
                       ^
./Modules/grpmodule.c:205:24: warning: unused variable 'buf2' [-Wunused-variable]
    char *buf = NULL, *buf2 = NULL, *name_chars;
                       ^
./Modules/grpmodule.c:287:5: error: implicit declaration of function 'setgrent' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
    setgrent();
    ^
./Modules/grpmodule.c:288:17: error: implicit declaration of function 'getgrent' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
    while ((p = getgrent()) != NULL) {
                ^

CPython versions tested on:

CPython main branch

Operating systems tested on:

Other

Linked PRs

• gh-114875: Add getgrent as a prerequisite for building the grp module #114876