Support for clang specific boost and protobuf dirs:

Clang does not understand gcc 5's new ABI. On linux systems
that default to the new ABI (such as ubuntu 15.10), building
with clang requires using C++ libraries built with the the old
gcc ABI.

When building with the clang protobuf lib, a common error is to
load the gcc protobuf library at run time. When set, PROTOBUF_ROOT
is added to rpath to make sure the correct lib is loaded.

Adds a script to install clang and download and build boost and
protobuf with boost.

Builds/Ubuntu/build_clang_libs.sh

@@ -0,0 +1,79 @@
+#!/usr/bin/env bash
+
+#
+# This scripts installs boost and protobuf built with clang. This is needed on
+# ubuntu 15.10 when building with clang
+# It will build these in a 'clang' subdirectory that it creates below the directory
+# this script is run from. If a clang directory already exists the script will refuse
+# to run.
+
+if hash lsb_release 2>/dev/null; then
+    if [ $(lsb_release -si) == "Ubuntu" ]; then
+        ubuntu_release=$(lsb_release -sr)
+    fi
+fi
+
+if [ -z "${ubuntu_release}" ]; then
+    echo "System not supported"
+    exit 1
+fi
+
+if ! hash clang 2>/dev/null; then
+    clang_version=3.7
+    sudo apt-get -y install clang-${clang_version}
+    update-alternatives --install /usr/bin/clang clang /usr/bin/clang-${clang_version} 99 clang++
+    hash -r
+    if ! hash clang 2>/dev/null; then
+        echo "Please install clang"
+        exit 1
+    fi
+fi
+
+if [ ${ubuntu_release} != "15.10" ]; then
+    echo "clang specific boost and protobuf not needed"
+    exit 0
+fi
+
+if [ -d clang ]; then
+    echo "clang directory already exists. Cowardly refusing to run"
+    exit 1
+fi
+
+if ! hash wget 2>/dev/null; then
+    sudo apt-get -y install wget
+    hash -r
+    if ! hash wget 2>/dev/null; then
+        echo "Please install wget"
+        exit 1
+    fi
+fi
+
+num_procs=$(lscpu -p | grep -v '^#' | sort -u -t, -k 2,4 | wc -l) # pysical cores
+
+mkdir clang
+pushd clang > /dev/null
+
+# Install protobuf
+pb=protobuf-2.6.1
+pb_tar=${pb}.tar.gz 
+wget -O ${pb_tar} https://github.com/google/protobuf/releases/download/v2.6.1/${pb_tar}
+tar xf ${pb_tar}
+rm ${pb_tar}
+pushd ${pb} > /dev/null
+./configure CC=clang CXX=clang++ CXXFLAGS='-std=c++14 -O3 -g'
+make -j${num_procs}
+popd > /dev/null
+
+# Install boost
+boost_ver=1.60.0
+bd=boost_${boost_ver//./_}
+bd_tar=${bd}.tar.gz
+wget -O ${bd_tar} http://sourceforge.net/projects/boost/files/boost/${boost_ver}/${bd_tar}
+tar xf ${bd_tar}
+rm ${bd_tar}
+pushd ${bd} > /dev/null
+./bootstrap.sh
+./b2 toolset=clang -j${num_procs}
+popd > /dev/null
+
+popd > /dev/null

SConstruct

@@ -61,10 +61,16 @@ The following environment variables modify the build environment:
       Path to the boost directory.
     OPENSSL_ROOT
       Path to the openssl directory.
-    PROTOBUF_DIR
-      Path to the protobuf directory. This is usually only needed when
-      the installed protobuf library uses a different ABI than clang
-      (as with ubuntu 15.10).
+    PROTOBUF_ROOT
+      Path to the protobuf directory.
+    CLANG_PROTOBUF_ROOT
+      Override the path to the protobuf directory for the clang toolset. This is
+      usually only needed when the installed protobuf library uses a different
+      ABI than clang (as with ubuntu 15.10).
+    CLANG_BOOST_ROOT
+      Override the path to the boost directory for the clang toolset. This is
+      usually only needed when the installed protobuf library uses a different
+      ABI than clang (as with ubuntu 15.10).
 
 The following extra options may be used:
     --ninja         Generate a `build.ninja` build file for the specified target
@@ -356,21 +362,6 @@ def config_base(env):
         ,'-DBOOST_NO_AUTO_PTR'
         ])
 
-    try:
-        BOOST_ROOT = os.path.normpath(os.environ['BOOST_ROOT'])
-        env.Append(LIBPATH=[
-            os.path.join(BOOST_ROOT, 'stage', 'lib'),
-            ])
-        env['BOOST_ROOT'] = BOOST_ROOT
-    except KeyError:
-        pass
-
-    try:
-        protobuf_dir = os.environ['PROTOBUF_DIR']
-        env.Append(LIBPATH=[protobuf_dir])
-    except KeyError:
-        pass
-
     if Beast.system.windows:
         try:
             OPENSSL_ROOT = os.path.normpath(os.environ['OPENSSL_ROOT'])
@@ -444,21 +435,52 @@ def add_sanitizer (toolchain, env):
     add_static_libs(env, [san_to_lib[san]])
     env.Append(CPPDEFINES=['SANITIZER='+san_to_lib[san].upper()])
 
-# Set toolchain and variant specific construction variables
-def config_env(toolchain, variant, env):
-    if is_debug_variant(variant):
-        env.Append(CPPDEFINES=['DEBUG', '_DEBUG'])
+def add_boost_and_protobuf(toolchain, env):
+    def get_environ_value(candidates):
+        for c in candidates:
+            try:
+                return os.environ[c]
+            except KeyError:
+                pass
+        raise KeyError('Environment variable not set')
 
-    elif variant == 'release' or variant == 'profile':
-        env.Append(CPPDEFINES=['NDEBUG'])
-
-    if 'BOOST_ROOT' in env:
+    try:
+        br_cands = ['CLANG_BOOST_ROOT'] if toolchain == 'clang' else []
+        br_cands.append('BOOST_ROOT')
+        BOOST_ROOT = os.path.normpath(get_environ_value(br_cands))
+        env.Append(LIBPATH=[
+            os.path.join(BOOST_ROOT, 'stage', 'lib'),
+            ])
+        env['BOOST_ROOT'] = BOOST_ROOT
         if toolchain == 'gcc':
             env.Append(CCFLAGS=['-isystem' + env['BOOST_ROOT']])
         else:
             env.Append(CPPPATH=[
                 env['BOOST_ROOT'],
                 ])
+    except KeyError:
+        pass
+
+    try:
+        pb_cands = ['CLANG_PROTOBUF_ROOT'] if toolchain == 'clang' else []
+        pb_cands.append('PROTOBUF_ROOT')
+        PROTOBUF_ROOT = os.path.normpath(get_environ_value(pb_cands))
+        env.Append(LIBPATH=[PROTOBUF_ROOT + '/src/.libs'])
+        if not should_link_static() and toolchain in['clang', 'gcc']:
+            env.Append(LINKFLAGS=['-Wl,-rpath,' + PROTOBUF_ROOT + '/src/.libs'])
+        env['PROTOBUF_ROOT'] = PROTOBUF_ROOT
+        env.Append(CPPPATH=[env['PROTOBUF_ROOT'] + '/src',])
+    except KeyError:
+        pass
+
+# Set toolchain and variant specific construction variables
+def config_env(toolchain, variant, env):
+    add_boost_and_protobuf(toolchain, env)
+    if is_debug_variant(variant):
+        env.Append(CPPDEFINES=['DEBUG', '_DEBUG'])
+
+    elif variant == 'release' or variant == 'profile':
+        env.Append(CPPDEFINES=['NDEBUG'])
 
     if should_link_static() and not Beast.system.linux:
         raise Exception("Static linking is only implemented for linux.")