Check whether -std=c++11 can be safely added to the compiler flags

.github/workflows/test.yaml

@@ -8,10 +8,17 @@ jobs:
   tests:
     name: tests
     strategy:
+      fail-fast: false
       matrix:
+        os: [ubuntu-latest]
         pyver: [3.7, 3.8, 3.9]
+        compiler: [gcc]
+        include:
+            - os: macos-latest
+              pyver: 3.9
+              compiler: clang
 
-    runs-on: "ubuntu-latest"
+    runs-on: ${{ matrix.os }}
 
     steps:
       - uses: actions/checkout@v2
@@ -22,6 +29,8 @@ jobs:
           python-version: ${{ matrix.pyver }}
 
       - name: Install code
+        env:
+            CC: ${{ matrix.compiler }}
         run: pip install -e .
 
       - name: lint

setup.py

@@ -24,7 +24,7 @@
 local_tmp = "tmp"
 
 
-def try_compile(cpp_code, compiler, cflags=[], lflags=[]):
+def try_compile(cpp_code, compiler, cflags=[], lflags=[], c_not_cpp=False):
     """
     Check if compiling some code with the given compiler and flags works
     properly.
@@ -38,7 +38,7 @@ def try_compile(cpp_code, compiler, cflags=[], lflags=[]):
     # tmp directory so the user can troubleshoot the problem if they were
     # expecting it to work.
     with tempfile.NamedTemporaryFile(
-        delete=False, suffix=".cpp", dir=local_tmp
+        delete=False, suffix=".c" if c_not_cpp else ".cpp" , dir=local_tmp
     ) as cpp_file:
         cpp_file.write(cpp_code.encode())
         cpp_name = cpp_file.name
@@ -81,6 +81,9 @@ def try_compile(cpp_code, compiler, cflags=[], lflags=[]):
         # Don't delete files in case helpful for troubleshooting.
         return False
 
+    if lflags == []:
+        return returncode == 0
+
     # Link
     cc = compiler.linker_so[0]
     cmd = [cc] + compiler.linker_so[1:] + lflags + [o_name, "-o", exe_name]
@@ -111,7 +114,10 @@ def check_flags(compiler):
     cflags = extra_compile_args
     lflags = extra_link_args
 
-    cflags += ["-std=c++11"]
+    # Check whether we can safely add -std=c++11
+    if try_compile("int main (int argc, char **argv) { return 0; }",
+                   compiler, ["-std=c++11"], [], c_not_cpp=True):
+        cflags += ["-std=c++11"]
 
     if platform.system() == "Darwin":
         # Usually Macs need this, but they might not, so try it, and only add