+dnl Check that strcasestr is present and works.
+AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE],
+[
+ AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+
+ dnl Persuade glibc <string.h> to declare strcasestr().
+ AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
+ AC_REQUIRE([gl_FUNC_MEMCHR])
+ AC_CHECK_FUNCS([strcasestr])
+ if test $ac_cv_func_strcasestr = no; then
+ HAVE_STRCASESTR=0
+ else
+ if test "$gl_cv_func_memchr_works" != yes; then
+ REPLACE_STRCASESTR=1
+ else
+ dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+ AC_CACHE_CHECK([whether strcasestr works],
+ [gl_cv_func_strcasestr_works_always],
+ [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h> /* for strcasestr */
+#define P "_EF_BF_BD"
+#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
+#define NEEDLE P P P P P
+]], [[return !!strcasestr (HAYSTACK, NEEDLE);
+ ]])],
+ [gl_cv_func_strcasestr_works_always=yes],
+ [gl_cv_func_strcasestr_works_always=no],
+ [dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not
+ dnl affected, since it uses different source code for strcasestr
+ dnl than glibc.
+ dnl Assume that it works on all other platforms, even if it is not
+ dnl linear.
+ AC_EGREP_CPP([Lucky user],
+ [
+#ifdef __GNU_LIBRARY__
+ #include <features.h>
+ #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
+ || defined __UCLIBC__
+ Lucky user
+ #endif
+#elif defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
+ Lucky user
+ #endif
+#else
+ Lucky user
+#endif
+ ],
+ [gl_cv_func_strcasestr_works_always="guessing yes"],
+ [gl_cv_func_strcasestr_works_always="guessing no"])
+ ])
+ ])
+ case "$gl_cv_func_strcasestr_works_always" in
+ *yes) ;;
+ *)
+ REPLACE_STRCASESTR=1
+ ;;
+ esac
+ fi
+ fi
+]) # gl_FUNC_STRCASESTR_SIMPLE
+
+dnl Additionally, check that strcasestr is efficient.