From fbe3b8ebb4bd549548943edd4d1b83f2d759228d Mon Sep 17 00:00:00 2001
From: Fabian Groffen <grobian@gentoo.org>
Date: Mon, 27 Nov 2017 14:54:44 +0100
Subject: [PATCH] app-crypt/libb2: addUSE=native-cflags to control feature
 guessing

Package-Manager: Portage-2.3.13, Repoman-2.3.3
---
 app-crypt/libb2/libb2-0.98.ebuild | 10 ++++++----
 app-crypt/libb2/metadata.xml      |  8 ++++++++
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/app-crypt/libb2/libb2-0.98.ebuild b/app-crypt/libb2/libb2-0.98.ebuild
index 08bf237662f2..b42921bc69d2 100644
--- a/app-crypt/libb2/libb2-0.98.ebuild
+++ b/app-crypt/libb2/libb2-0.98.ebuild
@@ -13,7 +13,7 @@ SRC_URI="https://github.com/BLAKE2/libb2/archive/${GITHASH}.tar.gz -> ${P}.tar.g
 LICENSE="CC0-1.0"
 SLOT="0"
 KEYWORDS="~amd64 ~ppc64"
-IUSE="static"
+IUSE="static native-cflags"
 
 DEPEND=""
 RDEPEND="${DEPEND}"
@@ -28,12 +28,14 @@ src_prepare() {
 }
 
 src_configure() {
-	econf $(use_enable static)
+	econf \
+		$(use_enable static) \
+		$(use_enable native-cflags native)
 }
 
 src_compile() {
-	# respect our CFLAGS
-	emake CFLAGS="${CFLAGS}"
+	# respect our CFLAGS when native-cflags is not in effect
+	emake $(use native-cflags && echo no)CFLAGS="${CFLAGS}"
 }
 
 src_install() {
diff --git a/app-crypt/libb2/metadata.xml b/app-crypt/libb2/metadata.xml
index 5ef83e989e93..76fd7590acbb 100644
--- a/app-crypt/libb2/metadata.xml
+++ b/app-crypt/libb2/metadata.xml
@@ -10,4 +10,12 @@
 
 		Official implementations from BLAKE2 project.
 	</longdescription>
+	<use>
+		<flag name="native-cflags">
+		Use CFLAGS as determined by configure script.  These flags will
+		enable all CPU specific features it find available, to further
+		optimise the implementation.  This discards any existing CFLAGS
+		set in make.conf or similar.
+		</flag>
+	</use>
 </pkgmetadata>
-- 
2.26.2