Merge usage of download_dir and wheel_download_dir

In every cases, at least one of them is None.  By doing this,
it is also possible to simplify wrapper codes around download_dir.

src/pip/_internal/cli/req_command.py

@@ -203,7 +203,6 @@ def make_requirement_preparer(
         finder,                   # type: PackageFinder
         use_user_site,            # type: bool
         download_dir=None,        # type: str
-        wheel_download_dir=None,  # type: str
     ):
         # type: (...) -> RequirementPreparer
         """
@@ -229,7 +228,6 @@ def make_requirement_preparer(
             build_dir=temp_build_dir_path,
             src_dir=options.src_dir,
             download_dir=download_dir,
-            wheel_download_dir=wheel_download_dir,
             build_isolation=options.build_isolation,
             req_tracker=req_tracker,
             session=session,

src/pip/_internal/commands/wheel.py

@@ -137,7 +137,7 @@ def run(self, options, args):
             req_tracker=req_tracker,
             session=session,
             finder=finder,
-            wheel_download_dir=options.wheel_dir,
+            download_dir=options.wheel_dir,
             use_user_site=False,
         )
 

src/pip/_internal/operations/prepare.py

@@ -300,7 +300,6 @@ def __init__(
         build_dir,  # type: str
         download_dir,  # type: Optional[str]
         src_dir,  # type: str
-        wheel_download_dir,  # type: Optional[str]
         build_isolation,  # type: bool
         req_tracker,  # type: RequirementTracker
         session,  # type: PipSession
@@ -325,16 +324,6 @@ def __init__(
         # not saved, and are deleted immediately after unpacking.
         self.download_dir = download_dir
 
-        # Where still-packed .whl files should be written to. If None, they are
-        # written to the download_dir parameter. Separate to download_dir to
-        # permit only keeping wheel archives for pip wheel.
-        self.wheel_download_dir = wheel_download_dir
-
-        # NOTE
-        # download_dir and wheel_download_dir overlap semantically and may
-        # be combined if we're willing to have non-wheel archives present in
-        # the wheelhouse output by 'pip wheel'.
-
         # Is build isolation allowed?
         self.build_isolation = build_isolation
 
@@ -371,15 +360,8 @@ def _log_preparing_link(self, req):
             with indent_log():
                 logger.info("Using cached %s", req.link.filename)
 
-    def _get_download_dir(self, link):
-        # type: (Link) -> Optional[str]
-        if link.is_wheel and self.wheel_download_dir:
-            # Download wheels to a dedicated dir when doing `pip wheel`.
-            return self.wheel_download_dir
-        return self.download_dir
-
-    def _ensure_link_req_src_dir(self, req, download_dir, parallel_builds):
-        # type: (InstallRequirement, Optional[str], bool) -> None
+    def _ensure_link_req_src_dir(self, req, parallel_builds):
+        # type: (InstallRequirement, bool) -> None
         """Ensure source_dir of a linked InstallRequirement."""
         # Since source_dir is only set for editable requirements.
         if req.link.is_wheel:
@@ -480,10 +462,9 @@ def prepare_linked_requirement(self, req, parallel_builds=False):
             # Check if the relevant file is already available
             # in the download directory
             file_path = None
-            download_dir = self._get_download_dir(req.link)
-            if download_dir is not None and link.is_wheel:
+            if self.download_dir is not None and link.is_wheel:
                 hashes = self._get_linked_req_hashes(req)
-                file_path = _check_download_dir(req.link, download_dir, hashes)
+                file_path = _check_download_dir(req.link, self.download_dir, hashes)
 
             if file_path is not None:
                 # The file is already available, so mark it as downloaded
@@ -514,15 +495,14 @@ def _prepare_linked_requirement(self, req, parallel_builds):
         # type: (InstallRequirement, bool) -> Distribution
         assert req.link
         link = req.link
-        download_dir = self._get_download_dir(link)
 
-        self._ensure_link_req_src_dir(req, download_dir, parallel_builds)
+        self._ensure_link_req_src_dir(req, parallel_builds)
         hashes = self._get_linked_req_hashes(req)
         if link.url not in self._downloaded:
             try:
                 local_file = unpack_url(
                     link, req.source_dir, self._download,
-                    download_dir, hashes,
+                    self.download_dir, hashes,
                 )
             except NetworkConnectionError as exc:
                 raise InstallationError(
@@ -544,20 +524,21 @@ def _prepare_linked_requirement(self, req, parallel_builds):
             req, self.req_tracker, self.finder, self.build_isolation,
         )
 
-        if download_dir:
+        if self.download_dir is not None:
             if link.is_existing_dir():
                 logger.info('Link is a directory, ignoring download_dir')
             elif local_file:
-                download_location = os.path.join(download_dir, link.filename)
+                download_location = os.path.join(
+                    self.download_dir, link.filename
+                )
                 if not os.path.exists(download_location):
                     shutil.copy(local_file.path, download_location)
                     download_path = display_path(download_location)
                     logger.info('Saved %s', download_path)
 
         if link.is_vcs:
             # Make a .zip of the source_dir we already created.
-            if self.download_dir is not None:
-                req.archive(self.download_dir)
+            req.archive(self.download_dir)
         return dist
 
     def prepare_editable_requirement(
@@ -579,14 +560,13 @@ def prepare_editable_requirement(
                     'hash.'.format(req)
                 )
             req.ensure_has_source_dir(self.src_dir)
-            req.update_editable(not self._download_should_save)
+            req.update_editable(self.download_dir is None)
 
             dist = _get_prepared_distribution(
                 req, self.req_tracker, self.finder, self.build_isolation,
             )
 
-            if self._download_should_save:
-                req.archive(self.download_dir)
+            req.archive(self.download_dir)
             req.check_if_exists(self.use_user_site)
 
         return dist

src/pip/_internal/req/req_install.py

@@ -700,12 +700,14 @@ def _clean_zip_name(name, prefix):
         return self.name + '/' + name
 
     def archive(self, build_dir):
-        # type: (str) -> None
+        # type: (Optional[str]) -> None
         """Saves archive to provided build_dir.
 
         Used for saving downloaded VCS requirements as part of `pip download`.
         """
         assert self.source_dir
+        if build_dir is None:
+            return
 
         create_archive = True
         archive_name = '{}-{}.zip'.format(self.name, self.metadata["version"])

tests/unit/test_req.py

@@ -82,7 +82,6 @@ def _basic_resolver(self, finder, require_hashes=False):
                 build_dir=os.path.join(self.tempdir, 'build'),
                 src_dir=os.path.join(self.tempdir, 'src'),
                 download_dir=None,
-                wheel_download_dir=None,
                 build_isolation=True,
                 req_tracker=tracker,
                 session=session,