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