[patch] Ban nameref variables from exported and default scope

0001-Ban-nameref-variables-from-exported-and-default-scop.patch (text/plain), 1.85 KB, created by Ulrich Müller on 2021-05-25 16:20:46 UTC

From 364746528f55a84c683dfb0e80a30a1b649fdd64 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ulrich=20M=C3=BCller?= <[e-mail]>
Date: Tue, 25 May 2021 17:59:13 +0200
Subject: [PATCH] Ban nameref variables from exported and default scope
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Nameref variables will break detection of Bash arrays. The default
src_prepare() has this test:

    [[ $(declare -p PATCHES 2>/dev/null) == "declare -a"* ]]

If PATCHES is a name reference and its target is an array, then
declare -p will _not_ resolve the indirection, but output "declare -n"
instead.

We could work around this by updating the test to:

    ( unset "PATCHES[1]" 2>/dev/null )

using the fact that unset will return an error status when applied
to an element (other than the zeroth) of a scalar variable. However,
this looks like a very hackish solution which could break with future
Bash versions.

Bug: https://bugs.gentoo.org/636652
Signed-off-by: Ulrich Müller <[e-mail]>
---
 ebuild-format.tex | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ebuild-format.tex b/ebuild-format.tex
index 4929ba4..3f45242 100644
--- a/ebuild-format.tex
+++ b/ebuild-format.tex
@@ -11,6 +11,8 @@ compatibility settings (e.\,g.\ the \t{BASH_COMPAT} variable) are not exported t
 option of bash is set in the global scope of ebuilds. If set, failed pattern matches during
 filename expansion result in an error when the ebuild is being sourced.
 
+Name reference variables (introduced in Bash version~4.3) must not be used, except in local scope.
+
 The file encoding must be UTF-8 with Unix-style newlines. When sourced, the ebuild must define
 certain variables and functions (see chapters~\ref{ch:ebuild-vars} and~\ref{ch:ebuild-functions}
 for specific information), and must not call any external programs, write anything to standard
-- 
2.31.1