Use -std=c++14 flag when available on clang and gcc

setup.py

@@ -1,6 +1,6 @@
 from setuptools import setup, Extension
 from setuptools.command.build_ext import build_ext
-import sys
+import os, sys
 
 ext_modules = [
     Extension(
@@ -11,12 +11,41 @@ ext_modules = [
     ),
 ]
 
+def has_flag(compiler, flagname):
+    """Return a boolean indicating whether a flag name is supported on
+    the specified compiler.
+    """
+    import tempfile
+    fd, fname = tempfile.mkstemp('.cpp', 'main', text=True)
+    f = os.fdopen(fd, 'w')
+    try:
+        f.write('int main (int argc, char **argv) { return 0; }')
+    finally:
+        f.close()
+    try:
+        compiler.compile([fname], extra_postargs=[flagname])
+    except setuptools.distutils.errors.CompileError:
+        return False
+    return True
+
+def cpp_flag(compiler):
+    """Return the -std=c++[11/14] compiler flag.
+
+    The c++14 is prefered over c++11 (when it is available).
+    """
+    if has_flag(compiler, '-std=c++14'):
+        return '-std=c++14'
+    elif has_flag(compiler, '-std=c++11'):
+        return '-std=c++11'
+    else:
+        raise RuntimeError('Unsupported compiler -- at least C++11 support is needed!')
+
 
 class BuildExt(build_ext):
     """A custom build extension for adding compiler-specific options."""
     c_opts = {
         'msvc': ['/EHsc'],
-        'unix': ['-std=c++11'],
+        'unix': [],
     }
 
     if sys.platform == 'darwin':
@@ -25,6 +54,8 @@ class BuildExt(build_ext):
     def build_extensions(self):
         ct = self.compiler.compiler_type
         opts = self.c_opts.get(ct, [])
+        if ct == 'unix':
+            opts.append(cpp_flag(self.compiler))
         for ext in self.extensions:
             ext.extra_compile_args = opts
         build_ext.build_extensions(self)