Cleaned up c++11 config a bit

c++11.pri

@@ -0,0 +1,38 @@
+macx {
+  # Mac needs special care to link against the correct C++ library
+  # We attempt to auto-detect it by inspecting Boost
+  dirs = $${BOOSTDIR} $${QMAKE_LIBDIR}
+  for(dir, dirs) {
+    system(grep -q __112basic_string $${dir}/libboost_thread* >& /dev/null) {
+      message("Using libc++11")
+      CONFIG += libc++
+    }
+    else {
+      message("Using libstdc++")
+      CONFIG += libstdc++
+      c++11 {
+        # libc++ is a requirement for using C++11 
+        warning("Disabling C++11 since libstdc++ dependencies were found")
+        CONFIG -= c++11
+      }
+    }
+  }
+
+  libc++ {
+    QMAKE_CXXFLAGS += -stdlib=libc++
+    QMAKE_LFLAGS += -stdlib=libc++
+    QMAKE_OBJECTIVE_CFLAGS += -stdlib=libc++
+    # libc++ on requires Mac OS X 10.7+
+    QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.7
+  }
+}
+
+c++11 {
+  QMAKE_CXXFLAGS += -std=c++11
+  message("Using C++11")
+}
+else {
+  *clang* {
+    QMAKE_CXXFLAGS_WARN_ON += -Wno-c++11-extensions
+  }
+}

common.pri

@@ -17,3 +17,4 @@ include(harfbuzz.pri)
 include(freetype.pri)
 include(fontconfig.pri)
 include(scintilla.pri)
+include(c++11.pri)

openscad.pro

@@ -63,8 +63,6 @@ macx:isEmpty(OPENSCAD_LIBDIR) {
   QMAKE_LIBDIR = $$OPENSCAD_LIBDIR/lib
 }
 
-CONFIG += c++11
-
 # add CONFIG+=deploy to the qmake command-line to make a deployment build
 deploy {
   message("Building deployment version")
@@ -86,41 +84,9 @@ macx {
   APP_RESOURCES.files = OpenSCAD.sdef dsa_pub.pem icons/SCAD.icns
   QMAKE_BUNDLE_DATA += APP_RESOURCES
   LIBS += -framework Cocoa -framework ApplicationServices
-
-  # Mac needs special care to link against the correct C++ library
-  # We attempt to auto-detect it by inspecting Boost
-  dirs = $${BOOSTDIR} $${QMAKE_LIBDIR}
-  for(dir, dirs) {
-    system(grep -q __112basic_string $${dir}/libboost_thread* >& /dev/null) {
-      message("Using libc++11")
-      CONFIG += libc++
-    }
-    else {
-      message("Using libstdc++")
-      CONFIG += libstdc++
-    }
-  }
-
-  c++11 {
-    libstdc++: error("libc++ vs. libstdc++ conflict: Dependencies must be linked with libc++")
-    else: CONFIG += libc++
-  }
-
-  libc++ {
-    QMAKE_CXXFLAGS += -stdlib=libc++
-    QMAKE_LFLAGS += -stdlib=libc++
-    QMAKE_OBJECTIVE_CFLAGS += -stdlib=libc++
-    # libc++ on requires Mac OS X 10.7+
-    QMAKE_MACOSX_DEPLOYMENT_TARGET = 10.7
-  }
 }
 
 
-c++11 {
-  QMAKE_CXXFLAGS += -std=c++11
-  message("Using C++11")
-}
-
 win* {
   RC_FILE = openscad_win32.rc
   QTPLUGIN += qtaccessiblewidgets
@@ -174,7 +140,6 @@ netbsd* {
   QMAKE_CXXFLAGS_WARN_ON += -Wno-unused-parameter
   QMAKE_CXXFLAGS_WARN_ON += -Wno-unused-variable
   QMAKE_CXXFLAGS_WARN_ON += -Wno-unused-function
-  QMAKE_CXXFLAGS_WARN_ON += -Wno-c++11-extensions
   # might want to actually turn this on once in a while
   QMAKE_CXXFLAGS_WARN_ON += -Wno-sign-compare
 }
@@ -186,6 +151,7 @@ CONFIG(skip-version-check) {
 
 # Application configuration
 macx:CONFIG += mdi
+CONFIG += c++11
 CONFIG += cgal
 CONFIG += opencsg
 CONFIG += boost