Merge pull request #3179

4 files changed, 128 insertions, 132 deletions

diff --git a/setuptools/_distutils/_macos_compat.py b/setuptools/_distutils/_macos_compat.py
new file mode 100644
index 00000000..17769e91
--- /dev/null
+++ b/setuptools/_distutils/_macos_compat.py
@@ -0,0 +1,12 @@
+import sys
+import importlib
+
+
+def bypass_compiler_fixup(cmd, args):
+    return cmd
+
+
+if sys.platform == 'darwin':
+    compiler_fixup = importlib.import_module('_osx_support').compiler_fixup
+else:
+    compiler_fixup = bypass_compiler_fixup
diff --git a/setuptools/_distutils/sysconfig.py b/setuptools/_distutils/sysconfig.py
index 4a77a431..9fad3835 100644
--- a/setuptools/_distutils/sysconfig.py
+++ b/setuptools/_distutils/sysconfig.py
@@ -436,51 +436,6 @@ def expand_makefile_vars(s, vars):
 _config_vars = None
 
 
-_sysconfig_name_tmpl = '_sysconfigdata_{abi}_{platform}_{multiarch}'
-
-
-def _init_posix():
-    """Initialize the module as appropriate for POSIX systems."""
-    # _sysconfigdata is generated at build time, see the sysconfig module
-    name = os.environ.get(
-        '_PYTHON_SYSCONFIGDATA_NAME',
-        _sysconfig_name_tmpl.format(
-            abi=sys.abiflags,
-            platform=sys.platform,
-            multiarch=getattr(sys.implementation, '_multiarch', ''),
-        ),
-    )
-    try:
-        _temp = __import__(name, globals(), locals(), ['build_time_vars'], 0)
-    except ImportError:
-        # Python 3.5 and pypy 7.3.1
-        _temp = __import__(
-            '_sysconfigdata', globals(), locals(), ['build_time_vars'], 0)
-    build_time_vars = _temp.build_time_vars
-    global _config_vars
-    _config_vars = {}
-    _config_vars.update(build_time_vars)
-
-
-def _init_nt():
-    """Initialize the module as appropriate for NT"""
-    g = {}
-    # set basic install directories
-    g['LIBDEST'] = get_python_lib(plat_specific=0, standard_lib=1)
-    g['BINLIBDEST'] = get_python_lib(plat_specific=1, standard_lib=1)
-
-    # XXX hmmm.. a normal install puts include files here
-    g['INCLUDEPY'] = get_python_inc(plat_specific=0)
-
-    g['EXT_SUFFIX'] = _imp.extension_suffixes()[0]
-    g['EXE'] = ".exe"
-    g['VERSION'] = get_python_version().replace(".", "")
-    g['BINDIR'] = os.path.dirname(os.path.abspath(sys.executable))
-
-    global _config_vars
-    _config_vars = g
-
-
 def get_config_vars(*args):
     """With no arguments, return a dictionary of all configuration
     variables relevant for the current platform.  Generally this includes
@@ -493,60 +448,7 @@ def get_config_vars(*args):
     """
     global _config_vars
     if _config_vars is None:
-        func = globals().get("_init_" + os.name)
-        if func:
-            func()
-        else:
-            _config_vars = {}
-
-        # Normalized versions of prefix and exec_prefix are handy to have;
-        # in fact, these are the standard versions used most places in the
-        # Distutils.
-        _config_vars['prefix'] = PREFIX
-        _config_vars['exec_prefix'] = EXEC_PREFIX
-
-        if not IS_PYPY:
-            # For backward compatibility, see issue19555
-            SO = _config_vars.get('EXT_SUFFIX')
-            if SO is not None:
-                _config_vars['SO'] = SO
-
-            # Always convert srcdir to an absolute path
-            srcdir = _config_vars.get('srcdir', project_base)
-            if os.name == 'posix':
-                if python_build:
-                    # If srcdir is a relative path (typically '.' or '..')
-                    # then it should be interpreted relative to the directory
-                    # containing Makefile.
-                    base = os.path.dirname(get_makefile_filename())
-                    srcdir = os.path.join(base, srcdir)
-                else:
-                    # srcdir is not meaningful since the installation is
-                    # spread about the filesystem.  We choose the
-                    # directory containing the Makefile since we know it
-                    # exists.
-                    srcdir = os.path.dirname(get_makefile_filename())
-            _config_vars['srcdir'] = os.path.abspath(os.path.normpath(srcdir))
-
-            # Convert srcdir into an absolute path if it appears necessary.
-            # Normally it is relative to the build directory.  However, during
-            # testing, for example, we might be running a non-installed python
-            # from a different directory.
-            if python_build and os.name == "posix":
-                base = project_base
-                if (not os.path.isabs(_config_vars['srcdir']) and
-                    base != os.getcwd()):
-                    # srcdir is relative and we are not in the same directory
-                    # as the executable. Assume executable is in the build
-                    # directory and make srcdir absolute.
-                    srcdir = os.path.join(base, _config_vars['srcdir'])
-                    _config_vars['srcdir'] = os.path.normpath(srcdir)
-
-        # OS X platforms require special customization to handle
-        # multi-architecture, multi-os-version installers
-        if sys.platform == 'darwin':
-            import _osx_support
-            _osx_support.customize_config_vars(_config_vars)
+        _config_vars = sysconfig.get_config_vars().copy()
 
     if args:
         vals = []
diff --git a/setuptools/_distutils/tests/test_unixccompiler.py b/setuptools/_distutils/tests/test_unixccompiler.py
index 4574f77f..c8b4c149 100644
--- a/setuptools/_distutils/tests/test_unixccompiler.py
+++ b/setuptools/_distutils/tests/test_unixccompiler.py
@@ -3,6 +3,7 @@ import os
 import sys
 import unittest
 from test.support import run_unittest
+from unittest.mock import patch
 
 from .py38compat import EnvironmentVarGuard
 
@@ -215,6 +216,42 @@ class UnixCCompilerTestCase(support.TempdirManager, unittest.TestCase):
         self.assertEqual(self.cc.linker_so[0], 'my_cc')
 
     @unittest.skipIf(sys.platform == 'win32', "can't test on Windows")
+    def test_cc_overrides_ldshared_for_cxx_correctly(self):
+        """
+        Ensure that setting CC env variable also changes default linker
+        correctly when building C++ extensions.
+
+        pypa/distutils#126
+        """
+        def gcv(v):
+            if v == 'LDSHARED':
+                return 'gcc-4.2 -bundle -undefined dynamic_lookup '
+            elif v == 'CXX':
+                return 'g++-4.2'
+            return 'gcc-4.2'
+
+        def gcvs(*args, _orig=sysconfig.get_config_vars):
+            if args:
+                return list(map(sysconfig.get_config_var, args))
+            return _orig()
+
+        sysconfig.get_config_var = gcv
+        sysconfig.get_config_vars = gcvs
+        with patch.object(self.cc, 'spawn', return_value=None) as mock_spawn, \
+                patch.object(self.cc, '_need_link', return_value=True), \
+                patch.object(self.cc, 'mkpath', return_value=None), \
+                EnvironmentVarGuard() as env:
+            env['CC'] = 'ccache my_cc'
+            env['CXX'] = 'my_cxx'
+            del env['LDSHARED']
+            sysconfig.customize_compiler(self.cc)
+            self.assertEqual(self.cc.linker_so[0:2], ['ccache', 'my_cc'])
+            self.cc.link(None, [], 'a.out', target_lang='c++')
+            call_args = mock_spawn.call_args[0][0]
+            expected = ['my_cxx', '-bundle', '-undefined', 'dynamic_lookup']
+            assert call_args[:4] == expected
+
+    @unittest.skipIf(sys.platform == 'win32', "can't test on Windows")
     def test_explicit_ldshared(self):
         # Issue #18080:
         # ensure that setting CC env variable does not change
diff --git a/setuptools/_distutils/unixccompiler.py b/setuptools/_distutils/unixccompiler.py
index a07e5988..715408f5 100644
--- a/setuptools/_distutils/unixccompiler.py
+++ b/setuptools/_distutils/unixccompiler.py
@@ -22,9 +22,7 @@ from distutils.ccompiler import \
 from distutils.errors import \
      DistutilsExecError, CompileError, LibError, LinkError
 from distutils import log
-
-if sys.platform == 'darwin':
-    import _osx_support
+from ._macos_compat import compiler_fixup
 
 # XXX Things not currently handled:
 #   * optimization/debug/warning flags; we just use whatever's in Python's
@@ -42,6 +40,66 @@ if sys.platform == 'darwin':
 #     options and carry on.
 
 
+def _split_env(cmd):
+    """
+    For macOS, split command into 'env' portion (if any)
+    and the rest of the linker command.
+
+    >>> _split_env(['a', 'b', 'c'])
+    ([], ['a', 'b', 'c'])
+    >>> _split_env(['/usr/bin/env', 'A=3', 'gcc'])
+    (['/usr/bin/env', 'A=3'], ['gcc'])
+    """
+    pivot = 0
+    if os.path.basename(cmd[0]) == "env":
+        pivot = 1
+        while '=' in cmd[pivot]:
+            pivot += 1
+    return cmd[:pivot], cmd[pivot:]
+
+
+def _split_aix(cmd):
+    """
+    AIX platforms prefix the compiler with the ld_so_aix
+    script, so split that from the linker command.
+
+    >>> _split_aix(['a', 'b', 'c'])
+    ([], ['a', 'b', 'c'])
+    >>> _split_aix(['/bin/foo/ld_so_aix', 'gcc'])
+    (['/bin/foo/ld_so_aix'], ['gcc'])
+    """
+    pivot = os.path.basename(cmd[0]) == 'ld_so_aix'
+    return cmd[:pivot], cmd[pivot:]
+
+
+def _linker_params(linker_cmd, compiler_cmd):
+    """
+    The linker command usually begins with the compiler
+    command (possibly multiple elements), followed by zero or more
+    params for shared library building.
+
+    If the LDSHARED env variable overrides the linker command,
+    however, the commands may not match.
+
+    Return the best guess of the linker parameters by stripping
+    the linker command. If the compiler command does not
+    match the linker command, assume the linker command is
+    just the first element.
+
+    >>> _linker_params('gcc foo bar'.split(), ['gcc'])
+    ['foo', 'bar']
+    >>> _linker_params('gcc foo bar'.split(), ['other'])
+    ['foo', 'bar']
+    >>> _linker_params('ccache gcc foo bar'.split(), 'ccache gcc'.split())
+    ['foo', 'bar']
+    >>> _linker_params(['gcc'], ['gcc'])
+    []
+    """
+    c_len = len(compiler_cmd)
+    pivot = c_len if linker_cmd[:c_len] == compiler_cmd else 1
+    return linker_cmd[pivot:]
+
+
 class UnixCCompiler(CCompiler):
 
     compiler_type = 'unix'
@@ -109,10 +167,8 @@ class UnixCCompiler(CCompiler):
                 raise CompileError(msg)
 
     def _compile(self, obj, src, ext, cc_args, extra_postargs, pp_opts):
-        compiler_so = self.compiler_so
-        if sys.platform == 'darwin':
-            compiler_so = _osx_support.compiler_fixup(compiler_so,
-                                                    cc_args + extra_postargs)
+        compiler_so = compiler_fixup(
+            self.compiler_so, cc_args + extra_postargs)
         try:
             self.spawn(compiler_so + cc_args + [src, '-o', obj] +
                        extra_postargs)
@@ -173,33 +229,22 @@ class UnixCCompiler(CCompiler):
                 ld_args.extend(extra_postargs)
             self.mkpath(os.path.dirname(output_filename))
             try:
-                if target_desc == CCompiler.EXECUTABLE:
-                    linker = self.linker_exe[:]
-                else:
-                    linker = self.linker_so[:]
+                # Select a linker based on context: linker_exe when
+                # building an executable or linker_so (with shared options)
+                # when building a shared library.
+                building_exe = target_desc == CCompiler.EXECUTABLE
+                linker = (self.linker_exe if building_exe else self.linker_so)[:]
+
                 if target_lang == "c++" and self.compiler_cxx:
-                    # skip over environment variable settings if /usr/bin/env
-                    # is used to set up the linker's environment.
-                    # This is needed on OSX. Note: this assumes that the
-                    # normal and C++ compiler have the same environment
-                    # settings.
-                    i = 0
-                    if os.path.basename(linker[0]) == "env":
-                        i = 1
-                        while '=' in linker[i]:
-                            i += 1
-
-                    if os.path.basename(linker[i]) == 'ld_so_aix':
-                        # AIX platforms prefix the compiler with the ld_so_aix
-                        # script, so we need to adjust our linker index
-                        offset = 1
-                    else:
-                        offset = 0
-
-                    linker[i+offset] = self.compiler_cxx[i]
-
-                if sys.platform == 'darwin':
-                    linker = _osx_support.compiler_fixup(linker, ld_args)
+                    env, linker_ne = _split_env(linker)
+                    aix, linker_na = _split_aix(linker_ne)
+                    _, compiler_cxx_ne = _split_env(self.compiler_cxx)
+                    _, linker_exe_ne = _split_env(self.linker_exe)
+
+                    params = _linker_params(linker_na, linker_exe_ne)
+                    linker = env + aix + compiler_cxx_ne + params
+
+                linker = compiler_fixup(linker, ld_args)
 
                 self.spawn(linker + ld_args)
             except DistutilsExecError as msg: