From 3cbefde37656f2d3655e020e5922d33f44834187 Mon Sep 17 00:00:00 2001
From: Doug Luce <doug@github.con.com>
Date: Thu, 18 Jun 2015 11:07:16 -0700
Subject: [PATCH] Add alloca() discovery to configure.ac

The build failed on FreeBSD as there is no alloca.h.  This patch is
lifted from the autoconf documentation.
---
 builtin.c    | 21 ++++++++++++++++-----
 configure.ac |  2 ++
 util.c       | 18 +++++++++++++++++-
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/builtin.c b/builtin.c
index 1e3f0854..4d538eac 100644
--- a/builtin.c
+++ b/builtin.c
@@ -1,10 +1,22 @@
 #define _BSD_SOURCE
 #define _XOPEN_SOURCE
 #include <sys/time.h>
-#ifdef WIN32
-  #include <malloc.h>
-#else
-  #include <alloca.h>
+#include <stdlib.h>
+#include <stddef.h>
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#elif !defined alloca
+# ifdef __GNUC__
+#  define alloca __builtin_alloca
+# elif defined _MSC_VER
+#  include <malloc.h>
+#  define alloca _alloca
+# elif !defined HAVE_ALLOCA
+#  ifdef  __cplusplus
+extern "C"
+#  endif
+void *alloca (size_t);
+# endif
 #endif
 #include <assert.h>
 #include <ctype.h>
@@ -13,7 +25,6 @@
 #ifdef HAVE_ONIGURUMA
 #include <oniguruma.h>
 #endif
-#include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include "builtin.h"
diff --git a/configure.ac b/configure.ac
index bf236194..ccbe8dcb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -123,6 +123,8 @@ AM_CONDITIONAL([ENABLE_DOCS], [test "x$enable_docs" != xno])
 AM_CONDITIONAL([ENABLE_ERROR_INJECTION], [test "x$enable_error_injection" = xyes])
 AM_CONDITIONAL([ENABLE_ALL_STATIC], [test "x$enable_all_static" = xyes])
 
+AC_FUNC_ALLOCA
+
 AC_FIND_FUNC([isatty], [c], [#include <unistd.h>], [0])
 AC_FIND_FUNC([_isatty], [c], [#include <io.h>], [0])
 AC_FIND_FUNC([strptime], [c], [#include <time.h>], [0, 0, 0])
diff --git a/util.c b/util.c
index f7e3f917..30419269 100644
--- a/util.c
+++ b/util.c
@@ -10,8 +10,24 @@
 #include <fcntl.h>
 #include <limits.h>
 #include <string.h>
-#include <stdlib.h>
 #include <unistd.h>
+#include <stdlib.h>
+#include <stddef.h>
+#ifdef HAVE_ALLOCA_H
+# include <alloca.h>
+#elif !defined alloca
+# ifdef __GNUC__
+#  define alloca __builtin_alloca
+# elif defined _MSC_VER
+#  include <malloc.h>
+#  define alloca _alloca
+# elif !defined HAVE_ALLOCA
+#  ifdef  __cplusplus
+extern "C"
+#  endif
+void *alloca (size_t);
+# endif
+#endif
 #ifndef WIN32
 #include <pwd.h>
 #endif