Always reinstall local distributions provided by the user

src/pip/_internal/index/collector.py

@@ -22,7 +22,7 @@
 from pip._internal.models.search_scope import SearchScope
 from pip._internal.network.utils import raise_for_status
 from pip._internal.utils.compat import lru_cache
-from pip._internal.utils.filetypes import ARCHIVE_EXTENSIONS
+from pip._internal.utils.filetypes import is_archive_file
 from pip._internal.utils.misc import pairwise, redact_auth_from_url
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import path_to_url, url_to_path
@@ -65,17 +65,6 @@ def _match_vcs_scheme(url):
     return None
 
 
-def _is_url_like_archive(url):
-    # type: (str) -> bool
-    """Return whether the URL looks like an archive.
-    """
-    filename = Link(url).filename
-    for bad_ext in ARCHIVE_EXTENSIONS:
-        if filename.endswith(bad_ext):
-            return True
-    return False
-
-
 class _NotHTML(Exception):
     def __init__(self, content_type, request_desc):
         # type: (str, str) -> None
@@ -130,7 +119,7 @@ def _get_html_response(url, session):
     3. Check the Content-Type header to make sure we got HTML, and raise
        `_NotHTML` otherwise.
     """
-    if _is_url_like_archive(url):
+    if is_archive_file(Link(url).filename):
         _ensure_html_response(url, session=session)
 
     logger.debug('Getting page %s', redact_auth_from_url(url))

src/pip/_internal/req/constructors.py

@@ -24,8 +24,8 @@
 from pip._internal.pyproject import make_pyproject_path
 from pip._internal.req.req_install import InstallRequirement
 from pip._internal.utils.deprecation import deprecated
-from pip._internal.utils.filetypes import ARCHIVE_EXTENSIONS
-from pip._internal.utils.misc import is_installable_dir, splitext
+from pip._internal.utils.filetypes import is_archive_file
+from pip._internal.utils.misc import is_installable_dir
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 from pip._internal.utils.urls import path_to_url
 from pip._internal.vcs import is_url, vcs
@@ -45,15 +45,6 @@
 operators = Specifier._operators.keys()
 
 
-def is_archive_file(name):
-    # type: (str) -> bool
-    """Return True if `name` is a considered as an archive file."""
-    ext = splitext(name)[1].lower()
-    if ext in ARCHIVE_EXTENSIONS:
-        return True
-    return False
-
-
 def _strip_extras(path):
     # type: (str) -> Tuple[str, Optional[str]]
     m = re.match(r'^(.+)(\[[^\]]+\])$', path)

src/pip/_internal/resolution/resolvelib/resolver.py

@@ -16,6 +16,8 @@
     PipDebuggingReporter,
     PipReporter,
 )
+from pip._internal.utils.deprecation import deprecated
+from pip._internal.utils.filetypes import is_archive_file
 from pip._internal.utils.misc import dist_is_editable
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
@@ -132,12 +134,14 @@ def resolve(self, root_reqs, check_supported_wheels):
 
             # Check if there is already an installation under the same name,
             # and set a flag for later stages to uninstall it, if needed.
-            # * There isn't, good -- no uninstalltion needed.
+            #
+            # * There is no existing installation. Nothing to uninstall.
             # * The --force-reinstall flag is set. Always reinstall.
             # * The installation is different in version or editable-ness, so
             #   we need to uninstall it to install the new distribution.
-            # * The installed version is the same as the pending distribution.
-            #   Skip this distrubiton altogether to save work.
+            # * The candidate is a local wheel. Do nothing.
+            # * The candidate is a local sdist. Print a deprecation warning.
+            # * The candidate is a local path. Always reinstall.
             installed_dist = self.factory.get_dist_to_uninstall(candidate)
             if installed_dist is None:
                 ireq.should_reinstall = False
@@ -147,6 +151,34 @@ def resolve(self, root_reqs, check_supported_wheels):
                 ireq.should_reinstall = True
             elif dist_is_editable(installed_dist) != candidate.is_editable:
                 ireq.should_reinstall = True
+            elif candidate.source_link.is_file:
+                if candidate.source_link.is_wheel:
+                    logger.info(
+                        "%s is already installed with the same version as the "
+                        "provided wheel. Use --force-reinstall to force an "
+                        "installation of the wheel.",
+                        ireq.name,
+                    )
+                    continue
+
+                looks_like_sdist = (
+                    is_archive_file(candidate.source_link.file_path)
+                    and candidate.source_link.ext != ".zip"
+                )
+                if looks_like_sdist:
+                    reason = (
+                        "Source distribution is being reinstalled despite an "
+                        "installed package having the same name and version as "
+                        "the installed package."
+                    )
+                    replacement = "use --force-reinstall"
+                    deprecated(
+                        reason=reason,
+                        replacement=replacement,
+                        gone_in="21.1",
+                        issue=8711,
+                    )
+                ireq.should_reinstall = True
             else:
                 continue
 

src/pip/_internal/utils/filetypes.py

@@ -1,5 +1,6 @@
 """Filetype information.
 """
+from pip._internal.utils.misc import splitext
 from pip._internal.utils.typing import MYPY_CHECK_RUNNING
 
 if MYPY_CHECK_RUNNING:
@@ -14,3 +15,12 @@
 ARCHIVE_EXTENSIONS = (
     ZIP_EXTENSIONS + BZ2_EXTENSIONS + TAR_EXTENSIONS + XZ_EXTENSIONS
 )
+
+
+def is_archive_file(name):
+    # type: (str) -> bool
+    """Return True if `name` is a considered as an archive file."""
+    ext = splitext(name)[1].lower()
+    if ext in ARCHIVE_EXTENSIONS:
+        return True
+    return False

tests/functional/test_new_resolver.py

@@ -1152,44 +1152,69 @@ def test_new_resolver_check_wheel_version_normalized(
     assert_installed(script, simple="0.1.0+local.1")
 
 
-def test_new_resolver_contraint_on_dep_with_extra(script):
-    create_basic_wheel_for_package(
+def test_new_resolver_does_reinstall_local_sdists(script):
+    archive_path = create_basic_sdist_for_package(
         script,
-        name="simple",
-        version="1",
-        depends=["dep[x]"],
+        "pkg",
+        "1.0",
     )
-    create_basic_wheel_for_package(
-        script,
-        name="dep",
-        version="1",
-        extras={"x": ["depx==1"]},
+    script.pip(
+        "install", "--no-cache-dir", "--no-index",
+        archive_path,
     )
-    create_basic_wheel_for_package(
-        script,
-        name="dep",
-        version="2",
-        extras={"x": ["depx==2"]},
+    assert_installed(script, pkg="1.0")
+
+    result = script.pip(
+        "install", "--no-cache-dir", "--no-index",
+        archive_path,
+        expect_stderr=True,
     )
-    create_basic_wheel_for_package(
+    assert "Installing collected packages: pkg" in result.stdout, str(result)
+    assert "DEPRECATION" in result.stderr, str(result)
+    assert_installed(script, pkg="1.0")
+
+
+def test_new_resolver_does_reinstall_local_paths(script):
+    pkg = create_test_package_with_setup(
         script,
-        name="depx",
-        version="1",
+        name="pkg",
+        version="1.0"
     )
-    create_basic_wheel_for_package(
-        script,
-        name="depx",
-        version="2",
+    script.pip(
+        "install", "--no-cache-dir", "--no-index",
+        pkg,
     )
+    assert_installed(script, pkg="1.0")
+
+    result = script.pip(
+        "install", "--no-cache-dir", "--no-index",
+        pkg,
+    )
+    assert "Installing collected packages: pkg" in result.stdout, str(result)
+    assert_installed(script, pkg="1.0")
 
-    constraints_txt = script.scratch_path / "constraints.txt"
-    constraints_txt.write_text("dep==1")
 
+def test_new_resolver_does_not_reinstall_when_from_a_local_index(script):
+    create_basic_sdist_for_package(
+        script,
+        "simple",
+        "0.1.0",
+    )
     script.pip(
         "install",
         "--no-cache-dir", "--no-index",
         "--find-links", script.scratch_path,
-        "--constraint", constraints_txt,
-        "simple",
+        "simple"
+    )
+    assert_installed(script, simple="0.1.0")
+
+    result = script.pip(
+        "install",
+        "--no-cache-dir", "--no-index",
+        "--find-links", script.scratch_path,
+        "simple"
     )
-    assert_installed(script, simple="1", dep="1", depx="1")
+    # Should not reinstall!
+    assert "Installing collected packages: simple" not in result.stdout, str(result)
+    assert "Requirement already satisfied: simple" in result.stdout, str(result)
+    assert_installed(script, simple="0.1.0")