GNU bug report logs - #34167
build: ensure no VLA is used

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: bug-gzip <at> gnu.org
Subject: build: ensure no VLA is used
Date: Mon, 21 Jan 2019 16:49:42 -0800

[Message part 1 (text/plain, inline)]

I'm pushing these to prevent use of VLAs:

[vla.txt (text/plain, inline)]

From 8aa53f1797315a541960d4225f00c9f27c9612fe Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering <at> fb.com>
Date: Sun, 20 Jan 2019 22:23:57 -0800
Subject: [PATCH 1/2] build: update gnulib to latest

---
 gnulib | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gnulib b/gnulib
index 4652c7b..5b490ef 160000
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 4652c7bafa60332145f1e05a7de5f48e1bc56226
+Subproject commit 5b490ef07f257a5dd41fc0b351c1a387b8a8f89c
-- 
2.20.1.2.gb21ebb671b


From 20540be6186c159880dda3a49a5827722c1a0ac9 Mon Sep 17 00:00:00 2001
From: Jim Meyering <meyering <at> fb.com>
Date: Sun, 20 Jan 2019 22:24:06 -0800
Subject: [PATCH 2/2] build: ensure no VLA is used

Cause developer builds to fail for any use of a VLA.
VLAs (variable length arrays) limit portability.
* configure.ac (nw): Remove -Wvla from the list of disabled warnings,
thus enabling the warning when configured with --enable-gcc-warnings.
(GNULIB_NO_VLA) Define, disabling use of VLAs in gnulib.  This commit
is functionally equivalent to coreutils' v8.30-44-gd26dece5d.
---
 configure.ac | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index db86a2a..9a2b635 100644
--- a/configure.ac
+++ b/configure.ac
@@ -59,6 +59,10 @@ gl_EARLY

 gl_INIT

+# Ensure VLAs are not used.
+# Note -Wvla is implicitly added by gl_MANYWARN_ALL_GCC
+AC_DEFINE([GNULIB_NO_VLA], [1], [Define to 1 to disable use of VLAs])
+
 AC_ARG_ENABLE([gcc-warnings],
   [AS_HELP_STRING([--enable-gcc-warnings],
      [turn on many GCC warnings (for developers; best with GNU make)])],
@@ -114,7 +118,6 @@ if test "$gl_gcc_warnings" = yes; then
   nw="$nw -Wredundant-decls"        # openat.h declares e.g., mkdirat
   nw="$nw -Wlogical-op"             # any use of fwrite provokes this
   nw="$nw -Wformat-nonliteral"      # who.c and pinky.c strftime uses
-  nw="$nw -Wvla"                    # warnings in gettext.h
   nw="$nw -Wnested-externs"         # use of XARGMATCH/verify_function__
   nw="$nw -Wswitch-enum"            # Too many warnings for now
   nw="$nw -Wswitch-default"         # Too many warnings for now
-- 
2.20.1.2.gb21ebb671b

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