Move Windows protection check to specific commands

news/5311.bugfix

@@ -0,0 +1 @@
+Fix "pip wheel pip" being blocked by the "don't use pip to modify itself" check

news/5312.bugfix

@@ -0,0 +1 @@
+Fix "pip wheel pip" being blocked by the "don't use pip to modify itself" check

src/pip/_internal/basecommand.py

@@ -11,7 +11,6 @@
 from pip._internal.baseparser import (
     ConfigOptionParser, UpdatingDefaultsHelpFormatter,
 )
-from pip._internal.compat import WINDOWS
 from pip._internal.download import PipSession
 from pip._internal.exceptions import (
     BadCommand, CommandError, InstallationError, PreviousBuildDirError,
@@ -321,23 +320,6 @@ def populate_requirement_set(requirement_set, args, options, finder,
                     'You must give at least one requirement to %(name)s '
                     '(see "pip help %(name)s")' % opts)
 
-        # On Windows, any operation modifying pip should be run as:
-        #     python -m pip ...
-        # See https://github.com/pypa/pip/issues/1299 for more discussion
-        should_show_use_python_msg = (
-            WINDOWS and
-            requirement_set.has_requirement("pip") and
-            os.path.basename(sys.argv[0]).startswith("pip")
-        )
-        if should_show_use_python_msg:
-            new_command = [
-                sys.executable, "-m", "pip"
-            ] + sys.argv[1:]
-            raise CommandError(
-                'To modify pip, please run the following command:\n{}'
-                .format(" ".join(new_command))
-            )
-
     def _build_package_finder(self, options, session,
                               platform=None, python_versions=None,
                               abi=None, implementation=None):

src/pip/_internal/commands/install.py

@@ -20,7 +20,10 @@
 from pip._internal.resolve import Resolver
 from pip._internal.status_codes import ERROR
 from pip._internal.utils.filesystem import check_path_owner
-from pip._internal.utils.misc import ensure_dir, get_installed_version
+from pip._internal.utils.misc import (
+    ensure_dir, get_installed_version,
+    protect_pip_from_modification_on_windows,
+)
 from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.wheel import WheelBuilder
 
@@ -291,6 +294,10 @@ def run(self, options, args):
                     )
                     resolver.resolve(requirement_set)
 
+                    protect_pip_from_modification_on_windows(
+                        modifying_pip=requirement_set.has_requirement("pip")
+                    )
+
                     # If caching is disabled or wheel is not installed don't
                     # try to build wheels.
                     if wheel and options.cache_dir:

src/pip/_internal/commands/uninstall.py

@@ -5,6 +5,7 @@
 from pip._internal.basecommand import Command
 from pip._internal.exceptions import InstallationError
 from pip._internal.req import InstallRequirement, parse_requirements
+from pip._internal.utils.misc import protect_pip_from_modification_on_windows
 
 
 class UninstallCommand(Command):
@@ -63,6 +64,11 @@ def run(self, options, args):
                     'You must give at least one requirement to %(name)s (see '
                     '"pip help %(name)s")' % dict(name=self.name)
                 )
+
+            protect_pip_from_modification_on_windows(
+                modifying_pip="pip" in reqs_to_uninstall
+            )
+
             for req in reqs_to_uninstall.values():
                 uninstall_pathset = req.uninstall(
                     auto_confirm=options.yes, verbose=self.verbosity > 0,

src/pip/_internal/utils/misc.py

@@ -26,8 +26,10 @@
 from pip._vendor.six.moves import input
 from pip._vendor.six.moves.urllib import parse as urllib_parse
 
-from pip._internal.compat import console_to_str, expanduser, stdlib_pkgs
-from pip._internal.exceptions import InstallationError
+from pip._internal.compat import (
+    WINDOWS, console_to_str, expanduser, stdlib_pkgs,
+)
+from pip._internal.exceptions import CommandError, InstallationError
 from pip._internal.locations import (
     running_under_virtualenv, site_packages, user_site, virtualenv_no_global,
     write_delete_marker_file,
@@ -868,3 +870,32 @@ def remove_auth_from_url(url):
     )
     surl = urllib_parse.urlunsplit(url_pieces)
     return surl
+
+
+def protect_pip_from_modification_on_windows(modifying_pip):
+    """Protection of pip.exe from modification on Windows
+
+    On Windows, any operation modifying pip should be run as:
+        python -m pip ...
+    """
+    pip_names = [
+        "pip.exe",
+        "pip{}.exe".format(sys.version_info[0]),
+        "pip{}.{}.exe".format(*sys.version_info[:2])
+    ]
+
+    # See https://github.com/pypa/pip/issues/1299 for more discussion
+    should_show_use_python_msg = (
+        modifying_pip and
+        WINDOWS and
+        os.path.basename(sys.argv[0]) in pip_names
+    )
+
+    if should_show_use_python_msg:
+        new_command = [
+            sys.executable, "-m", "pip"
+        ] + sys.argv[1:]
+        raise CommandError(
+            'To modify pip, please run the following command:\n{}'
+            .format(" ".join(new_command))
+        )

tests/functional/test_install.py

@@ -40,9 +40,8 @@ def test_pep518_uses_build_env(script, data, common_wheels, command, variant):
 def test_pep518_with_user_pip(script, virtualenv, pip_src,
                               data, common_wheels):
     virtualenv.system_site_packages = True
-    script.pip_install_local("--ignore-installed",
-                             "-f", common_wheels,
-                             "--user", pip_src)
+    script.pip("install", "--ignore-installed", "--user", pip_src,
+               use_module=True)
     system_pip_dir = script.site_packages_path / 'pip'
     system_pip_dir.rmtree()
     system_pip_dir.mkdir()