1# alloca.m4 serial 9
2dnl Copyright (C) 2002-2004, 2006-2007, 2009-2010 Free Software Foundation,
3dnl Inc.
4dnl This file is free software; the Free Software Foundation
5dnl gives unlimited permission to copy and/or distribute it,
6dnl with or without modifications, as long as this notice is preserved.
7
8AC_DEFUN([gl_FUNC_ALLOCA],
9[
10  dnl Work around a bug of AC_EGREP_CPP in autoconf-2.57.
11  AC_REQUIRE([AC_PROG_CPP])
12  AC_REQUIRE([AC_PROG_EGREP])
13
14  AC_REQUIRE([AC_FUNC_ALLOCA])
15  if test $ac_cv_func_alloca_works = no; then
16    gl_PREREQ_ALLOCA
17  fi
18
19  # Define an additional variable used in the Makefile substitution.
20  if test $ac_cv_working_alloca_h = yes; then
21    AC_CACHE_CHECK([for alloca as a compiler built-in], [gl_cv_rpl_alloca], [
22      AC_EGREP_CPP([Need own alloca], [
23#if defined __GNUC__ || defined _AIX || defined _MSC_VER
24        Need own alloca
25#endif
26        ], [gl_cv_rpl_alloca=yes], [gl_cv_rpl_alloca=no])
27    ])
28    if test $gl_cv_rpl_alloca = yes; then
29      dnl OK, alloca can be implemented through a compiler built-in.
30      AC_DEFINE([HAVE_ALLOCA], [1],
31        [Define to 1 if you have 'alloca' after including <alloca.h>,
32         a header that may be supplied by this distribution.])
33      ALLOCA_H=alloca.h
34    else
35      dnl alloca exists as a library function, i.e. it is slow and probably
36      dnl a memory leak. Don't define HAVE_ALLOCA in this case.
37      ALLOCA_H=
38    fi
39  else
40    ALLOCA_H=alloca.h
41  fi
42  AC_SUBST([ALLOCA_H])
43])
44
45# Prerequisites of lib/alloca.c.
46# STACK_DIRECTION is already handled by AC_FUNC_ALLOCA.
47AC_DEFUN([gl_PREREQ_ALLOCA], [:])
48