From 053a672668a26e86a312d80f7c3ac629ea73472e Mon Sep 17 00:00:00 2001
From: James Le Cuirot <chewi@gentoo.org>
Date: Tue, 12 Jun 2018 22:34:01 +0100
Subject: [PATCH] autotools.eclass: Add has_version workaround for cross-prefix
 builds

Closes: https://bugs.gentoo.org/655414
---
 eclass/autotools.eclass | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/eclass/autotools.eclass b/eclass/autotools.eclass
index 2bc70f7b3c00..4497af236faf 100644
--- a/eclass/autotools.eclass
+++ b/eclass/autotools.eclass
@@ -444,14 +444,30 @@ autotools_env_setup() {
 		for pv in ${_LATEST_AUTOMAKE[@]/#*:} ; do
 			# Break on first hit to respect _LATEST_AUTOMAKE order.
 			local hv_args=""
-			case ${EAPI:-0} in
-				5|6)
-					hv_args="--host-root"
-					;;
-				7)
-					hv_args="-b"
-					;;
-			esac
+			# Cross-prefix builds rely on non-standard behaviour where
+			# automake is executed from the target system instead of the
+			# build system. ROOT=/ in this context but in other
+			# contexts, ROOT=/ indicates that the target system is also
+			# the build system, so we can check the target system
+			# without negatively impacting anyone. However, we only do
+			# this when EPREFIX is set just to be on the safe side. See
+			# https://bugs.gentoo.org/655414.
+			if [[ ${ROOT} == / && -n ${EPREFIX} ]]; then
+				case ${EAPI:-0} in
+					7)
+						hv_args="-d"
+						;;
+				esac
+			else
+				case ${EAPI:-0} in
+					5|6)
+						hv_args="--host-root"
+						;;
+					7)
+						hv_args="-b"
+						;;
+				esac
+			fi
 			ROOT=/ has_version ${hv_args} "=sys-devel/automake-${pv}*" && export WANT_AUTOMAKE="${pv}" && break
 		done
 		[[ ${WANT_AUTOMAKE} == "latest" ]] && \
-- 
2.17.0