Add always-install-via-wheel feature

--no-binary does not disable wheel building anymore, so a wheel
is built during the install process and setup.py install is
not used anymore in this case

--build-option and --global-option are passed to setup.py bdist_wheel
in the pip install command, like it is done in the pip wheel command.

docs/html/cli/pip_install.rst

@@ -315,8 +315,9 @@ Per-requirement Overrides
 -------------------------
 
 Since version 7.0 pip supports controlling the command line options given to
-``setup.py`` via requirements files. This disables the use of wheels (cached or
-otherwise) for that package, as ``setup.py`` does not exist for wheels.
+``setup.py`` via requirements files. Unless the ``always-install-via-wheel``
+feature is enabled, this disables the use of wheels (cached or otherwise),
+as ``setup.py`` does not exist for wheels.
 
 The ``--global-option`` and ``--install-option`` options are used to pass
 options to ``setup.py``. For example:
@@ -334,6 +335,10 @@ script as:
 
  python setup.py --no-user-cfg install --prefix='/usr/local' --no-compile
 
+When the ``always-install-via-wheel`` feature is enabled, ``--install-option``
+is ignored, and ``--global-option`` is passed to the ``setup.py bdist_wheel``
+command that is used to create a wheel that will be installed.
+
 Note that the only way of giving more than one option to ``setup.py``
 is through multiple ``--global-option`` and ``--install-option``
 options, as shown in the example above. The value of each option is

news/9778.feature.rst

@@ -0,0 +1,11 @@
+Add an experimental ``always-install-via-wheel`` feature flag. When enabled, it has the
+following effects:
+
+- Installation of source distributions is always done by first building a wheel
+ then installing from it (assuming the ``wheel`` package is installed).
+- ``--no-binary`` now only means "do not download wheels" and
+ "do not use the wheel cache", whereas before it also
+ implied using the legacy ``setup.py install``.
+- ``--build-option`` and ``--global-option`` are passed to ``setup.py bdist_wheel``
+ during installation, as it was already done when using ``pip wheel``.
+- ``--install-option`` is ignored (because there is no ``setup.py install`` involved)

src/pip/_internal/cli/cmdoptions.py

@@ -501,12 +501,15 @@ def no_binary():
  callback=_handle_no_binary,
  type="str",
  default=format_control,
- help="Do not use binary packages. Can be supplied multiple times, and "
+ help="Do not download binary packages nor use the wheel cache. "
+ "Can be supplied multiple times, and "
  'each time adds to the existing value. Accepts either ":all:" to '
  'disable all binary packages, ":none:" to empty the set (notice '
  "the colons), or one or more package names with commas between "
  "them (no colons). Note that some packages are tricky to compile "
- "and may fail to install when this option is used on them.",
+ "and may fail to install when this option is used on them. "
+ "Additionally, this option forces the use of the legacy 'setup.py install' "
+ "path, unless the 'always-install-via-wheel' feature is enabled.",
  )
 
 
@@ -821,7 +824,8 @@ def _handle_no_use_pep517(option, opt, value, parser):
  'command (use like --install-option="--install-scripts=/usr/local/'
  'bin"). Use multiple --install-option options to pass multiple '
  "options to setup.py install. If you are using an option with a "
- "directory path, be sure to use absolute path.",
+ "directory path, be sure to use absolute path. "
+ "This option implies '--no-binary :all:'.",
 ) # type: Callable[..., Option]
 
 build_options = partial(
@@ -830,7 +834,10 @@ def _handle_no_use_pep517(option, opt, value, parser):
  dest="build_options",
  metavar="options",
  action="append",
- help="Extra arguments to be supplied to 'setup.py bdist_wheel'.",
+ help="Extra arguments to be supplied to 'setup.py bdist_wheel'. "
+ "This option implies '--no-binary :all:'."
+ "This option is ignored by the 'pip install' command unless the "
+ "'always-install-via-wheel' feature is enabled.",
 ) # type: Callable[..., Option]
 
 global_options = partial(
@@ -840,7 +847,8 @@ def _handle_no_use_pep517(option, opt, value, parser):
  action="append",
  metavar="options",
  help="Extra global options to be supplied to the setup.py "
- "call before the install or bdist_wheel command.",
+ "call before the install or bdist_wheel command. "
+ "This option implies '--no-binary :all:'.",
 ) # type: Callable[..., Option]
 
 no_clean = partial(
@@ -965,7 +973,7 @@ def check_list_path_option(options):
  metavar="feature",
  action="append",
  default=[],
- choices=["2020-resolver", "fast-deps", "in-tree-build"],
+ choices=["2020-resolver", "fast-deps", "in-tree-build", "always-install-via-wheel"],
  help="Enable new functionality, that may be backward incompatible.",
 ) # type: Callable[..., Option]
 

src/pip/_internal/commands/install.py

@@ -45,10 +45,12 @@
 logger = logging.getLogger(__name__)
 
 
-def get_check_binary_allowed(format_control):
- # type: (FormatControl) -> BinaryAllowedPredicate
+def get_check_binary_allowed(format_control, features_enabled):
+ # type: (FormatControl, List[str]) -> BinaryAllowedPredicate
  def check_binary_allowed(req):
  # type: (InstallRequirement) -> bool
+ if "always-install-via-wheel" in features_enabled:
+ return True
  canonical_name = canonicalize_name(req.name or "")
  allowed_formats = format_control.get_allowed_formats(canonical_name)
  return "binary" in allowed_formats
@@ -330,7 +332,7 @@ def run(self, options, args):
  )
 
  check_binary_allowed = get_check_binary_allowed(
- finder.format_control
+ finder.format_control, options.features_enabled
  )
 
  reqs_to_build = [

src/pip/_internal/wheel_builder.py

@@ -75,7 +75,7 @@ def _should_build(
 
  if not check_binary_allowed(req):
  logger.info(
- "Skipping wheel build for %s, due to binaries "
+ "Using legacy 'setup.py install' for %s, due to binaries "
  "being disabled for it.", req.name,
  )
  return False

tests/functional/test_install.py

@@ -724,6 +724,17 @@ def test_install_global_option(script):
  assert not result.files_created
 
 
+def test_install_global_option_does_not_disable_wheel_building(
+ script, data, with_wheel
+):
+ res = script.pip(
+ 'install', '--no-index', '--global-option=-v', '-f', data.find_links,
+ '--use-feature=always-install-via-wheel',
+ 'upper', expect_stderr=True)
+ assert "Successfully installed upper-2.0" in str(res), str(res)
+ assert "Building wheel for upper" in str(res), str(res)
+
+
 def test_install_with_hacked_egg_info(script, data):
  """
  test installing a package which defines its own egg_info class
@@ -1439,6 +1450,17 @@ def test_install_no_binary_disables_building_wheels(script, data, with_wheel):
  assert "Running setup.py install for upper" in str(res), str(res)
 
 
+def test_install_no_binary_does_not_disable_building_wheels(
+ script, data, with_wheel
+):
+ res = script.pip(
+ 'install', '--no-index', '--no-binary=upper', '-f', data.find_links,
+ '--use-feature=always-install-via-wheel',
+ 'upper', expect_stderr=True)
+ assert "Successfully installed upper-2.0" in str(res), str(res)
+ assert "Building wheel for upper" in str(res), str(res)
+
+
 @pytest.mark.network
 def test_install_no_binary_builds_pep_517_wheel(script, data, with_wheel):
  to_install = data.packages.joinpath('pep517_setup_and_pyproject')