rename from_metadata_file{,_contents}() to avoid ambiguity pointed ou…

…t by reviewer

src/pip/_internal/metadata/__init__.py

@@ -106,21 +106,22 @@ def get_wheel_distribution(wheel: Wheel, canonical_name: str) -> BaseDistributio
 
 
 def get_metadata_distribution(
-    metadata_path: str,
+    metadata_contents: bytes,
     filename: str,
     canonical_name: str,
 ) -> BaseDistribution:
-    """Get the representation of the specified METADATA file.
+    """Get the dist representation of the specified METADATA file contents.
 
-    This returns a Distribution instance from the chosen backend based on the contents
-    of the file at ``metadata_path``.
+    This returns a Distribution instance from the chosen backend sourced from the data
+    in `metadata_contents`.
 
-    :param metadata_path: Path to the METADATA file.
+    :param metadata_contents: Contents of a METADATA file within a dist, or one served
+                              via PEP 658.
     :param filename: Filename for the dist this metadata represents.
     :param canonical_name: Normalized project name of the given dist.
     """
-    return select_backend().Distribution.from_metadata_file(
-        metadata_path,
+    return select_backend().Distribution.from_metadata_file_contents(
+        metadata_contents,
         filename,
         canonical_name,
     )

src/pip/_internal/metadata/base.py

@@ -114,15 +114,18 @@ def from_directory(cls, directory: str) -> "BaseDistribution":
         raise NotImplementedError()
 
     @classmethod
-    def from_metadata_file(
+    def from_metadata_file_contents(
         cls,
-        metadata_path: str,
+        metadata_contents: bytes,
         filename: str,
         project_name: str,
     ) -> "BaseDistribution":
         """Load the distribution from the contents of a METADATA file.
 
-        :param metadata: The path to a METADATA file.
+        This is used to implement PEP 658 by generating a "shallow" dist object that can
+        be used for resolution without downloading or building the actual dist yet.
+
+        :param metadata_contents: The contents of a METADATA file.
         :param filename: File name for the dist with this metadata.
         :param project_name: Name of the project this dist represents.
         """

src/pip/_internal/metadata/importlib/_dists.py

@@ -28,6 +28,7 @@
 )
 from pip._internal.utils.misc import normalize_path
 from pip._internal.utils.packaging import safe_extra
+from pip._internal.utils.temp_dir import TempDirectory
 from pip._internal.utils.wheel import parse_wheel, read_wheel_metadata_file
 
 from ._compat import BasePath, get_dist_name
@@ -110,15 +111,22 @@ def from_directory(cls, directory: str) -> BaseDistribution:
         return cls(dist, info_location, info_location.parent)
 
     @classmethod
-    def from_metadata_file(
+    def from_metadata_file_contents(
         cls,
-        metadata_path: str,
+        metadata_contents: bytes,
         filename: str,
         project_name: str,
     ) -> BaseDistribution:
-        metadata_location = pathlib.Path(metadata_path)
-        dist = importlib.metadata.Distribution.at(metadata_location.parent)
-        return cls(dist, metadata_location.parent, None)
+        # Generate temp dir to contain the metadata file, and write the file contents.
+        temp_dir = pathlib.Path(
+            TempDirectory(kind="metadata", globally_managed=True).path
+        )
+        metadata_path = temp_dir / "METADATA"
+        with open(metadata_path, "wb") as f:
+            f.write(metadata_contents)
+        # Construct dist pointing to the newly created directory.
+        dist = importlib.metadata.Distribution.at(metadata_path.parent)
+        return cls(dist, metadata_path.parent, None)
 
     @classmethod
     def from_wheel(cls, wheel: Wheel, name: str) -> BaseDistribution:

src/pip/_internal/metadata/pkg_resources.py

@@ -93,20 +93,18 @@ def from_directory(cls, directory: str) -> BaseDistribution:
         return cls(dist)
 
     @classmethod
-    def from_metadata_file(
+    def from_metadata_file_contents(
         cls,
-        metadata_path: str,
+        metadata_contents: bytes,
         filename: str,
         project_name: str,
     ) -> BaseDistribution:
-        with open(metadata_path, "rb") as f:
-            metadata = f.read()
-        metadata_text = {
-            "METADATA": metadata,
+        metadata_dict = {
+            "METADATA": metadata_contents,
         }
         dist = pkg_resources.DistInfoDistribution(
             location=filename,
-            metadata=InMemoryMetadata(metadata_text, filename),
+            metadata=InMemoryMetadata(metadata_dict, filename),
             project_name=project_name,
         )
         return cls(dist)

src/pip/_internal/operations/prepare.py

@@ -374,19 +374,17 @@ def _fetch_metadata_using_link_data_attr(
             req.req,
             metadata_link,
         )
+        # Download the contents of the METADATA file, separate from the dist itself.
         metadata_file = get_http_url(
             metadata_link,
             self._download,
             hashes=metadata_link.as_hashes(),
         )
-        # The file will be downloaded under the same name as it's listed in the index,
-        # which will end with .metadata. To make importlib.metadata.PathDistribution
-        # work, we need to keep it in the same directory, but rename it to METADATA.
-        containing_dir = os.path.dirname(metadata_file.path)
-        new_metadata_path = os.path.join(containing_dir, "METADATA")
-        os.rename(metadata_file.path, new_metadata_path)
+        with open(metadata_file.path, "rb") as f:
+            metadata_contents = f.read()
+        # Generate a dist just from those file contents.
         return get_metadata_distribution(
-            new_metadata_path,
+            metadata_contents,
             req.link.filename,
             req.req.name,
         )