Merge pull request #16619 from mattip/c99-again2

BLD: check if std=c99 is really required

1 files changed, 18 insertions, 12 deletions

diff --git a/setup.py b/setup.py
index 0016deac0..1f5212676 100755
--- a/setup.py
+++ b/setup.py
@@ -189,7 +189,6 @@ def check_submodules():
     for line in status.splitlines():
         if line.startswith('-') or line.startswith('+'):
             raise ValueError('Submodule not clean: {}'.format(line))
-            
 
 
 class concat_license_files():
@@ -234,20 +233,27 @@ def get_build_overrides():
     """
     from numpy.distutils.command.build_clib import build_clib
     from numpy.distutils.command.build_ext import build_ext
+    from distutils.version import LooseVersion
 
-    def _is_using_gcc(obj):
-        is_gcc = False
-        if obj.compiler.compiler_type == 'unix':
-            cc = sysconfig.get_config_var("CC")
-            if not cc:
-                cc = ""
-            compiler_name = os.path.basename(cc)
-            is_gcc = "gcc" in compiler_name
-        return is_gcc
+    def _needs_gcc_c99_flag(obj):
+        if obj.compiler.compiler_type != 'unix':
+            return False
+
+        cc = obj.compiler.compiler[0]
+        if "gcc" not in cc:
+            return False
+
+        # will print something like '4.2.1\n'
+        out = subprocess.run([cc, '-dumpversion'], stdout=subprocess.PIPE,
+                             stderr=subprocess.PIPE, universal_newlines=True)
+        # -std=c99 is default from this version on
+        if LooseVersion(out.stdout) >= LooseVersion('5.0'):
+            return False
+        return True
 
     class new_build_clib(build_clib):
         def build_a_library(self, build_info, lib_name, libraries):
-            if _is_using_gcc(self):
+            if _needs_gcc_c99_flag(self):
                 args = build_info.get('extra_compiler_args') or []
                 args.append('-std=c99')
                 build_info['extra_compiler_args'] = args
@@ -255,7 +261,7 @@ def get_build_overrides():
 
     class new_build_ext(build_ext):
         def build_extension(self, ext):
-            if _is_using_gcc(self):
+            if _needs_gcc_c99_flag(self):
                 if '-std=c99' not in ext.extra_compile_args:
                     ext.extra_compile_args.append('-std=c99')
             build_ext.build_extension(self, ext)