./compat/have_strcasestr.c:10:13: error: call to undeclared function 'strcasestr'; ISO C99 and later do not support implicit function declarations [-Werror,-Wimplicit-function-declaration] found = strcasestr (haystack, needle); ^ ./compat/have_strcasestr.c:10:13: note: did you mean 'strcasecmp'? /usr/include/strings.h:116:12: note: 'strcasecmp' declared here extern int strcasecmp (const char *__s1, const char *__s2) ^ ./compat/have_strcasestr.c:10:11: error: incompatible integer to pointer conversion assigning to 'char *' from 'int' [-Wint-conversion] found = strcasestr (haystack, needle); ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 2 errors generated. ./compat/check_getpwuid.c:9:53: warning: null passed to a callee that requires a non-null argument [-Wnonnull] (void) getpwuid_r (0, &passwd, NULL, 0, &ignored); ~~~~ ^