always-install-via-wheel feature

src/pip/_internal/cli/cmdoptions.py

@@ -72,6 +72,12 @@ def check_install_build_global(options, check_options=None):
     :param check_options: The options to check, if not supplied defaults to
         options.
     """
+    if "always-install-via-wheel" in options.features_enabled:
+        # In this mode, we accept --global-option and --build-option that are
+        # passed to setup.py bdist_wheel. --install-option is not allowed at
+        # all in this mode, since setup.py install will not be used.
+        return
+
     if check_options is None:
         check_options = options
 
@@ -82,6 +88,7 @@ def getname(n):
     if any(map(getname, names)):
         control = options.format_control
         control.disallow_binaries()
+        # TODO this should be a deprecation
         warnings.warn(
             'Disabling all use of wheels due to the use of --build-option '
             '/ --global-option / --install-option.', stacklevel=2,
@@ -917,7 +924,7 @@ def check_list_path_option(options):
     metavar='feature',
     action='append',
     default=[],
-    choices=['2020-resolver', 'fast-deps'],
+    choices=['2020-resolver', 'fast-deps', 'always-install-via-wheel'],
     help='Enable new functionality, that may be backward incompatible.',
 )  # type: Callable[..., Option]
 

src/pip/_internal/commands/install.py

@@ -46,10 +46,12 @@
 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)
         allowed_formats = format_control.get_allowed_formats(canonical_name)
         return "binary" in allowed_formats
@@ -331,7 +333,7 @@ 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

@@ -81,7 +81,7 @@ 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