Abort sourcing for yash in posixlycorrect mode

The yash shell takes conformance so seriously that it goes as far as to
disable the local builtin in its posixlycorrect mode.

https://magicant.github.io/yash/doc/posix.html

$ yash -o posixlycorrect -c 'f() { local var; }; f'
yash: local: non-portable built-in is not supported in the POSIXly-correct mode

Signed-off-by: Kerin Millar <kfm@plushkava.net>

1 files changed, 15 insertions, 8 deletions

diff --git a/functions.sh b/functions.sh
index 733e4e9..1c8721f 100644
--- a/functions.sh
+++ b/functions.sh
@@ -30,10 +30,25 @@
 # SENTINEL         : can define a value separating two distinct argument lists
 # SYSTEMD_EXEC_PID : used by from_unit()
 # TERM             : used to detect dumb terminals
+# YASH_VERSION     : for detecting yash before checking for incompatible options
 
 #------------------------------------------------------------------------------#
 
 #
+# Prints a diagnostic message prefixed with the basename of the running script.
+#
+warn()
+{
+	printf '%s: %s\n' "${0##*/}" "$*" >&2
+}
+
+if [ "${YASH_VERSION}" ] && set +o | grep -qxF 'set -o posixlycorrect'; then
+	# The yash shell disables the local builtin in its POSIXly-correct mode.
+	warn "gentoo-functions does not support yash in posixlycorrect mode"
+	return 1
+fi
+
+#
 # Considers the first parameter as a reference to a variable by name and
 # assigns the second parameter as its value. If the first parameter is found
 # not to be a legal identifier, no assignment shall occur and the return value
@@ -706,14 +721,6 @@ trueof_any()
 }
 
 #
-# Prints a diagnostic message prefixed with the basename of the running script.
-#
-warn()
-{
-	printf '%s: %s\n' "${0##*/}" "$*" >&2
-}
-
-#
 # Considers the first parameter as a command name before trying to locate it as
 # a regular file. If not specified as an absolute pathname, a PATH search shall
 # be performed in accordance with the Environment Variables section of the Base