Hello, and a Happy New Year,
quoting memmem.m4:
AC_CACHE_CHECK([whether memmem works], [gl_cv_func_memmem_works],
[AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <string.h>],
[return !memmem ("a", 1, NULL, 0);])],
[gl_cv_func_memmem_works=yes], [gl_cv_func_memmem_works=no],
[dnl pessimistically assume the worst, since even glibc 2.6.1
dnl has quadratic complexity in its memmem
gl_cv_func_memmem_works=no])])
This sets gl_cv_func_memmem_works=yes in the non-cross-compiling case,
tested on GNU/Linux with glibc 2.3.6, which in turn causes the
test-memmem.c test to take an awful lot of time to complete (I killed
it after several minutes). I noticed this with git master M4.
I suggest that either the testsuite test use some time limit (alarm?),
or the configure test tries to expose the quadratic complexity, or the
configure test assume `no' on systems where we know libc's memmem to be
insufficient.
Cheers,
Ralf
