Better handling of conflicting --copies and --symlinks

Introduce priority of where the option is set to follow the order:
cli, env var, file, hard coded. If both set at same level prefer copy
over symlink.

Signed-off-by: Bernat Gabor <bgabor8@bloomberg.net>

docs/changelog/1784.bugfix.rst

@@ -0,0 +1,3 @@
+Better handling of conflicting :conf:`copies` and :conf:`symlinks`. Introduce priority of where the option is set to
+follow the order: CLI, env var, file, hardcoded. If both set at same level prefers copy over symlink. - by
+user:`gaborbernat`.

src/virtualenv/config/cli/parser.py

@@ -1,7 +1,8 @@
 from __future__ import absolute_import, unicode_literals
 
-from argparse import SUPPRESS, ArgumentDefaultsHelpFormatter, ArgumentParser
+from argparse import SUPPRESS, ArgumentDefaultsHelpFormatter, ArgumentParser, Namespace
 from collections import OrderedDict
+from contextlib import contextmanager
 
 from virtualenv.config.convert import get_type
 
@@ -28,6 +29,7 @@ def __init__(self, options=None, *args, **kwargs):
  self._options = options
  self._interpreter = None
  self._app_data = None
+ self._source = {}
 
  def _fix_defaults(self):
  for action in self._actions:
@@ -52,19 +54,44 @@ def _fix_default(self, action):
  break
  if outcome is not None:
  action.default, action.default_source = outcome
+ else:
+ outcome = action.default, "default"
+ if outcome[1].startswith("env var"):
+ outcome = outcome[0], "env var"
+ self._source[action.dest] = outcome
 
  def enable_help(self):
  self._fix_defaults()
  self.add_argument("-h", "--help", action="help", default=SUPPRESS, help="show this help message and exit")
 
  def parse_known_args(self, args=None, namespace=None):
- self._fix_defaults()
- return super(VirtualEnvConfigParser, self).parse_known_args(args, namespace=namespace)
+ with self._record_arg_src(namespace) as namespace:
+  return super(VirtualEnvConfigParser, self).parse_known_args(args, namespace=namespace)
 
  def parse_args(self, args=None, namespace=None):
- self._fix_defaults()
+ # this delegates to parse_known_args
  return super(VirtualEnvConfigParser, self).parse_args(args, namespace=namespace)
 
+ @contextmanager
+ def _record_arg_src(self, namespace):
+ inst = object()
+ self._fix_defaults()
+ if namespace is None:
+ namespace = Namespace()
+ for key in self._source:
+ setattr(namespace, key, inst)
+ try:
+ yield namespace
+ finally:
+ source = self._source.copy()
+ for key, default in self._source.items():
+ value = getattr(namespace, key)
+ if value is inst:
+ setattr(namespace, key, default[0])
+ else:
+ source[key] = (value, "cli")
+ namespace.key_to_source = source
+
 
 class HelpFormatter(ArgumentDefaultsHelpFormatter):
  def __init__(self, prog):

src/virtualenv/create/via_global_ref/api.py

@@ -34,11 +34,27 @@ def can_symlink(self):
 class ViaGlobalRefApi(Creator):
  def __init__(self, options, interpreter):
  super(ViaGlobalRefApi, self).__init__(options, interpreter)
- copies = getattr(options, "copies", False)
- symlinks = getattr(options, "symlinks", False)
- self.symlinks = symlinks is True and copies is False
+ self.symlinks = self._should_symlink(options)
  self.enable_system_site_package = options.system_site
 
+ @staticmethod
+ def _should_symlink(options):
+ # Priority of where the option is set to follow the order: CLI, env var, file, hardcoded.
+ # If both set at same level prefers copy over symlink.
+ copies_opt, symlinks_opt = options.key_to_source.get("copies"), options.key_to_source.get("symlinks")
+ symlinks, sym_src = symlinks_opt if symlinks_opt is not None else (False, None)
+ copies, copy_src = copies_opt if copies_opt is not None else (False, None)
+ for level in ["cli", "env var", "file", "default"]:
+ s_opt = symlinks if sym_src == level else None
+ c_opt = copies if copy_src == level else None
+ if s_opt is True and c_opt is True:
+ return False
+ if s_opt is True:
+ return True
+ if c_opt is True:
+ return False
+ return False # fallback to copy
+
  @classmethod
  def add_parser_arguments(cls, parser, interpreter, meta, app_data):
  super(ViaGlobalRefApi, cls).add_parser_arguments(parser, interpreter, meta, app_data)
@@ -50,6 +66,8 @@ def add_parser_arguments(cls, parser, interpreter, meta, app_data):
  help="give the virtual environment access to the system site-packages dir",
  )
  group = parser.add_mutually_exclusive_group()
+ if not meta.can_symlink and not meta.can_copy:
+ raise RuntimeError("neither symlink or copy method supported")
  if meta.can_symlink:
  group.add_argument(
  "--symlinks",

tests/unit/config/test_ini.py

@@ -0,0 +1,22 @@
+from textwrap import dedent
+
+from tests.unit.config.test_env_var import parse_cli
+from virtualenv.util.six import ensure_str
+
+
+def test_ini_can_be_overwritten_by_flag(tmp_path, monkeypatch):
+ custom_ini = tmp_path / "conf.ini"
+ custom_ini.write_text(
+ dedent(
+ """
+ [virtualenv]
+ copies = True
+ """
+ )
+ )
+ monkeypatch.setenv(ensure_str("VIRTUALENV_CONFIG_FILE"), str(custom_ini))
+
+ result = parse_cli(["venv", "--symlinks"])
+
+ symlinks = result.creator.symlinks
+ assert symlinks is True