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 3.2.3 and inadvertently dropped in 3.3.0.

3 files changed, 47 insertions, 4 deletions

diff --git a/Lib/distutils/sysconfig.py b/Lib/distutils/sysconfig.py
index b73503d..b947988 100644
--- a/Lib/distutils/sysconfig.py
+++ b/Lib/distutils/sysconfig.py
@@ -195,9 +195,15 @@ def customize_compiler(compiler):
             get_config_vars('CC', 'CXX', 'OPT', 'CFLAGS',
                             'CCSHARED', 'LDSHARED', 'SHLIB_SUFFIX', '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 1bff38e..a5a63fd 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.support import run_unittest
+from test.support import EnvironmentVarGuard, run_unittest
 
 from distutils import sysconfig
 from distutils.unixccompiler import UnixCCompiler
@@ -94,7 +95,6 @@ class UnixCCompilerTestCase(unittest.TestCase):
         sysconfig.get_config_var = gcv
         self.assertEqual(self.cc.rpath_foo(), '-Wl,--enable-new-dtags,-R/foo')
 
-
         # non-GCC GNULD
         sys.platform = 'bar'
         def gcv(v):
@@ -115,6 +115,38 @@ 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)
 
diff --git a/Misc/NEWS b/Misc/NEWS
index cb1a33a..828e240 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -55,6 +55,11 @@ Library
 - Issue #17269: Workaround for socket.getaddrinfo crash on MacOS X
   with port None or "0" and flags AI_NUMERICSERV.
 
+- 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 3.2.3 and inadvertently dropped in 3.3.0.
+
 IDLE
 ----