Issue #18080: When building a C extension module on OS X, if the compiler

is overriden with the CC environment variable, use the new compiler as
the default for linking if LDSHARED is not also overriden.  This restores
Distutils behavior introduced in 2.7.3 and inadvertently dropped in 2.7.4.

2 files changed, 41 insertions, 3 deletions

diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
index 0c726d9..4aa9334 100644
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -175,9 +175,15 @@ def customize_compiler(compiler):
                             'CCSHARED', 'LDSHARED', 'SO', 'AR',
                             'ARFLAGS')
 
-        newcc = None
         if 'CC' in os.environ:
-            cc = os.environ['CC']
+            newcc = os.environ['CC']
+            if (sys.platform == 'darwin'
+                    and 'LDSHARED' not in os.environ
+                    and ldshared.startswith(cc)):
+                # On OS X, if CC is overridden, use that as the default
+                #       command for LDSHARED as well
+                ldshared = newcc + ldshared[len(cc):]
+            cc = newcc
         if 'CXX' in os.environ:
             cxx = os.environ['CXX']
         if 'LDSHARED' in os.environ:
diff --git a/Lib/distutils/tests/test_unixccompiler.py b/Lib/distutils/tests/test_unixccompiler.py
index 40c908a..64f9d26 100644
--- a/Lib/distutils/tests/test_unixccompiler.py
+++ b/Lib/distutils/tests/test_unixccompiler.py
@@ -1,7 +1,8 @@
 """Tests for distutils.unixccompiler."""
+import os
 import sys
 import unittest
-from test.test_support import run_unittest
+from test.test_support import EnvironmentVarGuard, run_unittest
 
 from distutils import sysconfig
 from distutils.unixccompiler import UnixCCompiler
@@ -122,6 +123,37 @@ class UnixCCompilerTestCase(unittest.TestCase):
         sysconfig.get_config_var = gcv
         self.assertEqual(self.cc.rpath_foo(), '-R/foo')
 
+    @unittest.skipUnless(sys.platform == 'darwin', 'test only relevant for OS X')
+    def test_osx_cc_overrides_ldshared(self):
+        # Issue #18080:
+        # ensure that setting CC env variable also changes default linker
+        def gcv(v):
+            if v == 'LDSHARED':
+                return 'gcc-4.2 -bundle -undefined dynamic_lookup '
+            return 'gcc-4.2'
+        sysconfig.get_config_var = gcv
+        with EnvironmentVarGuard() as env:
+            env['CC'] = 'my_cc'
+            del env['LDSHARED']
+            sysconfig.customize_compiler(self.cc)
+        self.assertEqual(self.cc.linker_so[0], 'my_cc')
+
+    @unittest.skipUnless(sys.platform == 'darwin', 'test only relevant for OS X')
+    def test_osx_explict_ldshared(self):
+        # Issue #18080:
+        # ensure that setting CC env variable does not change
+        #   explicit LDSHARED setting for linker
+        def gcv(v):
+            if v == 'LDSHARED':
+                return 'gcc-4.2 -bundle -undefined dynamic_lookup '
+            return 'gcc-4.2'
+        sysconfig.get_config_var = gcv
+        with EnvironmentVarGuard() as env:
+            env['CC'] = 'my_cc'
+            env['LDSHARED'] = 'my_ld -bundle -dynamic'
+            sysconfig.customize_compiler(self.cc)
+        self.assertEqual(self.cc.linker_so[0], 'my_ld')
+
 
 def test_suite():
     return unittest.makeSuite(UnixCCompilerTestCase)