[PATCH] gnu: Add s2tc.

[Taylan Ulrich Bayırlı/Kammer]

This adds s2tc as an input to mesa, and uses a mesa-without-s2tc package
as an input to s2tc to solve a cyclic dependency.

The resulting s2tc package does *not* link to any libraries in the
mesa-without-s2tc package (it's not a requisite as per "guix gc -R"), so
this should be safe, as in the user won't end up with two different
libGL images in memory.

>From 9b23215a9ab474c2f03c6ae2c888672beb4b4f58 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Taylan=20Ulrich=20Bay=C4=B1rl=C4=B1/Kammer?=
 <address@hidden>
Date: Wed, 11 Mar 2015 21:49:24 +0100
Subject: [PATCH] gnu: Add s2tc.

* gnu/packages/gl.scm (s2tc): New variable.
(mesa): Add input s2tc.
(mesa-without-s2tc): New variable.
---
 gnu/packages/gl.scm | 43 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/gnu/packages/gl.scm b/gnu/packages/gl.scm
index 7d549d3..ba5f8a4 100644
--- a/gnu/packages/gl.scm
+++ b/gnu/packages/gl.scm
@@ -21,11 +21,13 @@
 
 (define-module (gnu packages gl)
   #:use-module (ice-9 match)
+  #:use-module (guix build utils)
   #:use-module ((guix licenses) #:prefix l:)
   #:use-module (guix packages)
   #:use-module (guix download)
   #:use-module (guix build-system gnu)
   #:use-module (guix packages)
+  #:use-module (gnu packages autotools)
   #:use-module (gnu packages bison)
   #:use-module (gnu packages flex)
   #:use-module (gnu packages pkg-config)
@@ -123,6 +125,38 @@ rendering modes are: Bitmaps, Anti-aliased pixmaps, 
Texture maps, Outlines,
 Polygon meshes, and Extruded polygon meshes")
     (license l:x11)))
 
+(define-public s2tc
+  (package
+    (name "s2tc")
+    (version "1.0")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append
+             "https://github.com/divVerent/s2tc/archive/v"; version ".tar.gz"))
+       (sha256
+        (base32 "0ibfdib277fhbqvxzan0bmglwnsl1y1rw2g8skvz82l1sfmmn752"))))
+    (build-system gnu-build-system)
+    (native-inputs
+     `(("autoconf" ,autoconf)
+       ("automake" ,automake)
+       ("libtool" ,libtool)))
+    (inputs
+     `(("mesa" ,mesa-without-s2tc)))
+    (arguments
+     '(#:phases
+       (alist-cons-after
+        'unpack 'autogen
+        (lambda _
+          (zero? (system* "sh" "autogen.sh")))
+        %standard-phases)))
+    (home-page "https://github.com/divVerent/s2tc";)
+    (synopsis "S3 Text Compression implementation")
+    (description
+     "S2TC is a patent-free S3TC compatible implementation and provides
+texture compression to Mesa.")
+    (license l:expat)))
+
 (define-public mesa
   (package
     (name "mesa")
@@ -153,7 +187,8 @@ Polygon meshes, and Extruded polygon meshes")
         ("libxml2" ,libxml2)
         ;; TODO: Add 'libva'
         ;; TODO: Add 'libxml2-python' for OpenGL ES 1.1 and 2.0 support
-        ("makedepend" ,makedepend)))
+        ("makedepend" ,makedepend)
+        ("s2tc" ,s2tc)))
     (native-inputs
       `(("pkg-config" ,pkg-config)
         ("gettext" ,gnu-gettext)
@@ -196,6 +231,12 @@ allows Mesa to be used in many different environments 
ranging from software
 emulation to complete hardware acceleration for modern GPUs.")
     (license l:x11)))
 
+(define-public mesa-without-s2tc
+  (package
+    (inherit mesa)
+    (name "mesa-without-s2tc")
+    (inputs (alist-delete "s2tc" (package-inputs mesa)))))
+
 (define-public glew
   (package
     (name "glew")
-- 
2.2.1