Remove hard-coded version from autotools build

Moves version fetch code into external shell script.
Adds another possibility to provide the version on compile
time by VERSION file. We still give higher priority to the
environment variable or the version from git if available.
Addresses #892

Makefile

@@ -7,6 +7,7 @@ WINDRES  ?= windres
 CFLAGS   ?= -Wall -O2
 CXXFLAGS ?= -Wall -O2
 LDFLAGS  ?= -Wall -O2 -Wl,--no-undefined
+CAT      ?= $(if $(filter $(OS),Windows_NT),type,cat)
 
 ifneq (,$(findstring /cygdrive/,$(PATH)))
 	UNAME := Cygwin
@@ -28,6 +29,12 @@ ifeq "$(LIBSASS_VERSION)" ""
   endif
 endif
 
+ifeq "$(LIBSASS_VERSION)" ""
+  ifneq ("$(wildcard VERSION)","")
+    LIBSASS_VERSION ?= $(shell $(CAT) VERSION)
+  endif
+endif
+
 ifneq "$(LIBSASS_VERSION)" ""
   CFLAGS   += -DLIBSASS_VERSION="\"$(LIBSASS_VERSION)\""
   CXXFLAGS += -DLIBSASS_VERSION="\"$(LIBSASS_VERSION)\""

Makefile.am

@@ -1,12 +1,19 @@
 ACLOCAL_AMFLAGS = -I m4
 
 AM_LDFLAGS = -lstdc++ -lm
-AM_CFLAGS = -Wall -fPIC
-AM_CXXFLAGS = -Wall -fPIC
-AM_CFLAGS += -DLIBSASS_VERSION="\"$(LIBSASS_VERSION)\""
-AM_CXXFLAGS += -DLIBSASS_VERSION="\"$(LIBSASS_VERSION)\""
+AM_CFLAGS = -Wall
+AM_CXXFLAGS = -Wall
 
-AM_CXXFLAGS += -std=c++0x
+if COMPILER_IS_MINGW32
+  AM_CXXFLAGS += -std=gnu++0x
+else
+  AM_CFLAGS += -fPIC
+  AM_CXXFLAGS += -fPIC
+  AM_CXXFLAGS += -std=c++0x
+endif
+
+AM_CFLAGS += -DLIBSASS_VERSION="\"$(VERSION)\""
+AM_CXXFLAGS += -DLIBSASS_VERSION="\"$(VERSION)\""
 
 if ENABLE_COVERAGE
 	AM_CFLAGS += -O0 --coverage
@@ -18,8 +25,6 @@ else
 	AM_LDFLAGS += -O2
 endif
 
-VERSION = $(LIBSASS_VERSION)
-
 EXTRA_DIST = \
 	COPYING \
 	INSTALL \

configure.ac

@@ -2,7 +2,8 @@
 # Process this file with autoconf to produce a configure script.
 
 AC_PREREQ([2.61])
-AC_INIT([libsass], [3.0.3], [[email protected]])
+
+AC_INIT([libsass], m4_esyscmd_s([./version.sh]), [[email protected]])
 AC_CONFIG_SRCDIR([ast.hpp])
 AC_CONFIG_MACRO_DIR([m4])
 AC_CONFIG_HEADERS([config.h])
@@ -62,7 +63,7 @@ the --with-sass-spec-dir=<dir> argument.
   # Automake doesn't like its tests in an absolute path, so we make it relative.
   case $sass_spec_dir in
     /*)
-      SASS_SPEC_PATH=`$RUBY -e "require 'pathname';puts Pathname.new('$sass_spec_dir').relative_path_from(Pathname.new('$PWD')).to_s"`
+      SASS_SPEC_PATH=`$RUBY -e "require 'pathname'; puts Pathname.new('$sass_spec_dir').relative_path_from(Pathname.new('$PWD')).to_s"`
       ;;
     *)
       SASS_SPEC_PATH="$sass_spec_dir"
@@ -106,25 +107,10 @@ fi
 
 AM_CONDITIONAL(ENABLE_COVERAGE, test "x$enable_cov" = "xyes")
 
-AC_ARG_VAR(LIBSASS_VERSION, libsass version)
-if test "x$LIBSASS_VERSION" = "x"; then
-  AC_CHECK_PROG(GIT, git, git)
-  if test "x$GIT" = "x"; then
-    LIBSASS_VERSION=$VERSION
-  else
-    AC_CHECK_FILE(.git/config, [
-      LIBSASS_VERSION=`$GIT describe --abbrev=4 --dirty --always --tags`
-    ], [
-      LIBSASS_VERSION=$VERSION
-    ])
-  fi
-  if test "x$LIBSASS_VERSION" = "x"; then
-    AC_MSG_ERROR([LIBSASS_VERSION not defined.
-You can solve this by setting LIBSASS_VERSION:
-# export LIBSASS_VERSION="x.y.z"
-])
-  fi
-fi
+AS_CASE([$host], [*-*-mingw32], [is_mingw32=yes], [is_mingw32=no])
+AM_CONDITIONAL(COMPILER_IS_MINGW32, test "x$is_mingw32" = "xyes")
+
+AC_MSG_NOTICE([Building libsass ($VERSION)])
 
 AC_CONFIG_FILES([Makefile support/libsass.pc])
 AC_OUTPUT

version.sh

@@ -0,0 +1,10 @@
+if test "x$LIBSASS_VERSION" = "x"; then
+  LIBSASS_VERSION=`git describe --abbrev=4 --dirty --always --tags 2>/dev/null`
+fi
+if test "x$LIBSASS_VERSION" = "x"; then
+  LIBSASS_VERSION=`cat VERSION 2>/dev/null`
+fi
+if test "x$LIBSASS_VERSION" = "x"; then
+  LIBSASS_VERSION="[na]"
+fi
+echo $LIBSASS_VERSION