In looking into this I realized a couple of things. First, I partially
addressed this problem in 2006 in gnulib's AC_C_VARARRAYS macro (sorry,
I forgot about this until today). Second, the C standardization
committee addressed it in a different way, in C11's __STDC_NO_VLA__
macro. So just now I fixed gnulib to do things the C11 way. RCS should
be able to use the vararrays module of the updated gnulib, and then do
something like this:
/* A function's argument must point to an array with at least N
elements.
Example: 'int main (int argc, char *argv[VLA_ELEMS (argc)]);'. */
#ifdef __STDC_NO_VLA__
# define VLA_ELEMS(n)
#else
# define VLA_ELEMS(n) static n
#endif
I prefer the name VLA_ELEMS to ARSZ_FN_PARM, as it's shorter and more
mnemonic to people who are used to the standard terminology.
It might be helpful to have a gnulib module that implements VLA_ELEMS,
such as in the attached patch; what do you think? (I haven't installed it.)
From 0bc8d16b21f5985012d32bffa5e36059aff6c9a7 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Thu, 7 Aug 2014 17:40:01 -0700
Subject: [PATCH] vla: new module
* MODULES.html.sh: Add vla.
* lib/vla.h, modules/vla: New files.
---
ChangeLog | 4 ++++
MODULES.html.sh | 1 +
lib/vla.h | 27 +++++++++++++++++++++++++++
modules/vla | 20 ++++++++++++++++++++
4 files changed, 52 insertions(+)
create mode 100644 lib/vla.h
create mode 100644 modules/vla
diff --git a/ChangeLog b/ChangeLog
index 386520b..a610b5e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
2014-08-07 Paul Eggert <egg...@cs.ucla.edu>
+ vla: new module
+ * MODULES.html.sh: Add vla.
+ * lib/vla.h, modules/vla: New files.
+
vararrays: modernize AC_C_VARARRAYS for C11
This backports a change I recently made to Autoconf.
* m4/vararrays.m4 (AC_C_VARARRAYS): Define __STDC_NO_VLA__ if
diff --git a/MODULES.html.sh b/MODULES.html.sh
index 2163f94..6c4520a 100755
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -2043,6 +2043,7 @@ func_all_modules ()
func_module snippet/unused-parameter
func_module va-args
func_module vararrays
+ func_module vla
func_end_table
element="Sizes of integer types <limits.h>"
diff --git a/lib/vla.h b/lib/vla.h
new file mode 100644
index 0000000..05125a7
--- /dev/null
+++ b/lib/vla.h
@@ -0,0 +1,27 @@
+/* vla.h - variable length arrays
+
+ Copyright 2014 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ Written by Paul Eggert. */
+
+/* A function's argument must point to an array with at least N elements.
+ Example: 'int main (int argc, char *argv[VLA_ELEMS (argc)]);'. */
+
+#ifdef __STDC_NO_VLA__
+# define VLA_ELEMS(n)
+#else
+# define VLA_ELEMS(n) static n
+#endif
diff --git a/modules/vla b/modules/vla
new file mode 100644
index 0000000..a007f88
--- /dev/null
+++ b/modules/vla
@@ -0,0 +1,20 @@
+Description:
+Macros for dealing with variable length arrays.
+
+Files:
+lib/vla.h
+
+Depends-on:
+vararrays
+
+configure.ac:
+
+Makefile.am:
+
+Include:
+
+License:
+GPL
+
+Maintainer:
+all
--
1.9.3
