+
+ # Define an additional variable used in the Makefile substitution.
+ if test $ac_cv_working_alloca_h = yes; then
+ AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [
+ AC_EGREP_CPP([Need own alloca], [
+#if defined __GNUC__ || defined _AIX || defined _MSC_VER
+ Need own alloca
+#endif
+ ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
+ ])
+ if test $gl_cv_rpl_alloca = yes; then
+ dnl OK, alloca can be implemented through a compiler built-in.
+ AC_DEFINE([HAVE_ALLOCA], 1,
+ [Define to 1 if you have 'alloca' after including <alloca.h>,
+ a header that may be supplied by this distribution.])
+ ALLOCA_H=alloca.h
+ else
+ dnl alloca exists as a library function, i.e. it is slow and probably
+ dnl a memory leak. Don't define HAVE_ALLOCA in this case.
+ ALLOCA_H=
+ fi
+ else
+ ALLOCA_H=alloca.h
+ fi
+ AC_SUBST([ALLOCA_H])
+
+ AC_DEFINE(HAVE_ALLOCA_H, 1,
+ [Define HAVE_ALLOCA_H for backward compatibility with older code
+ that includes <alloca.h> only if HAVE_ALLOCA_H is defined.])