Merge branch 'master' into feature/implicit-bootstrapfeature/implicit-bootstrap

1 files changed, 22 insertions, 18 deletions

diff --git a/setuptools/build_meta.py b/setuptools/build_meta.py
index a1c951cf..b9e8a2b3 100644
--- a/setuptools/build_meta.py
+++ b/setuptools/build_meta.py
@@ -32,13 +32,12 @@ import sys
 import tokenize
 import shutil
 import contextlib
+import tempfile
 
 import setuptools
 import distutils
-from setuptools.py31compat import TemporaryDirectory
 
 from pkg_resources import parse_requirements
-from pkg_resources.py31compat import makedirs
 
 __all__ = ['get_requires_for_build_sdist',
            'get_requires_for_build_wheel',
@@ -76,17 +75,20 @@ class Distribution(setuptools.dist.Distribution):
             distutils.core.Distribution = orig
 
 
-def _to_str(s):
-    """
-    Convert a filename to a string (on Python 2, explicitly
-    a byte string, not Unicode) as distutils checks for the
-    exact type str.
+@contextlib.contextmanager
+def no_install_setup_requires():
+    """Temporarily disable installing setup_requires
+
+    Under PEP 517, the backend reports build dependencies to the frontend,
+    and the frontend is responsible for ensuring they're installed.
+    So setuptools (acting as a backend) should not try to install them.
     """
-    if sys.version_info[0] == 2 and not isinstance(s, str):
-        # Assume it's Unicode, as that's what the PEP says
-        # should be provided.
-        return s.encode(sys.getfilesystemencoding())
-    return s
+    orig = setuptools._install_setup_requires
+    setuptools._install_setup_requires = lambda attrs: None
+    try:
+        yield
+    finally:
+        setuptools._install_setup_requires = orig
 
 
 def _get_immediate_subdirectories(a_dir):
@@ -153,9 +155,10 @@ class _BuildMetaBackend(object):
 
     def prepare_metadata_for_build_wheel(self, metadata_directory,
                                          config_settings=None):
-        sys.argv = sys.argv[:1] + ['dist_info', '--egg-base',
-                                   _to_str(metadata_directory)]
-        self.run_setup()
+        sys.argv = sys.argv[:1] + [
+            'dist_info', '--egg-base', metadata_directory]
+        with no_install_setup_requires():
+            self.run_setup()
 
         dist_info_directory = metadata_directory
         while True:
@@ -190,12 +193,13 @@ class _BuildMetaBackend(object):
         result_directory = os.path.abspath(result_directory)
 
         # Build in a temporary directory, then copy to the target.
-        makedirs(result_directory, exist_ok=True)
-        with TemporaryDirectory(dir=result_directory) as tmp_dist_dir:
+        os.makedirs(result_directory, exist_ok=True)
+        with tempfile.TemporaryDirectory(dir=result_directory) as tmp_dist_dir:
             sys.argv = (sys.argv[:1] + setup_command +
                         ['--dist-dir', tmp_dist_dir] +
                         config_settings["--global-option"])
-            self.run_setup()
+            with no_install_setup_requires():
+                self.run_setup()
 
             result_basename = _file_with_extension(
                 tmp_dist_dir, result_extension)