site: use importlib instead of adhoc file searches

This change replaces various cases in which installed distribution and
file look-ups used path searches with importlib.metadata backed
look-ups.

This fixes issues with `dist-info` lookup for PEP610 implementation as
well as `.pth` file look-up and `dist-info` removal.

poetry/installation/executor.py

@@ -714,19 +714,6 @@ def _download_archive(self, operation: Union[Install, Update], link: Link) -> Pa
     def _should_write_operation(self, operation: Operation) -> bool:
         return not operation.skipped or self._dry_run or self._verbose
 
-    @staticmethod
-    def _package_dist_info_path(package: "Package") -> Path:
-        from poetry.core.masonry.utils.helpers import escape_name
-        from poetry.core.masonry.utils.helpers import escape_version
-
-        return Path(
-            f"{escape_name(package.pretty_name)}-{escape_version(package.version.text)}.dist-info"
-        )
-
-    @classmethod
-    def _direct_url_json_path(cls, package: "Package") -> Path:
-        return cls._package_dist_info_path(package) / "direct_url.json"
-
     def _save_url_reference(self, operation: "OperationTypes") -> None:
         """
         Create and store a PEP-610 `direct_url.json` file, if needed.
@@ -742,11 +729,12 @@ def _save_url_reference(self, operation: "OperationTypes") -> None:
             # distribution.
             # That's not what we want so we remove the direct_url.json file,
             # if it exists.
-            for direct_url in self._env.site_packages.find(
-                self._direct_url_json_path(package), True
+            for (
+                direct_url_json
+            ) in self._env.site_packages.find_distribution_direct_url_json_files(
+                distribution_name=package.name, writable_only=True
             ):
-                direct_url.unlink()
-
+                direct_url_json.unlink(missing_ok=True)
             return
 
         url_reference = None
@@ -761,15 +749,13 @@ def _save_url_reference(self, operation: "OperationTypes") -> None:
             url_reference = self._create_file_url_reference(package)
 
         if url_reference:
-            for path in self._env.site_packages.find(
-                self._package_dist_info_path(package), writable_only=True
+            for dist in self._env.site_packages.distributions(
+                name=package.name, writable_only=True
             ):
-                self._env.site_packages.write_text(
-                    path / "direct_url.json",
+                dist._path.joinpath("direct_url.json").write_text(
                     json.dumps(url_reference),
                     encoding="utf-8",
                 )
-                break
 
     def _create_git_url_reference(
         self, package: "Package"

poetry/installation/pip_installer.py

@@ -117,7 +117,9 @@ def remove(self, package: "Package") -> None:
             raise
 
         # This is a workaround for https://github.com/pypa/pip/issues/4176
-        for nspkg_pth_file in self._env.site_packages.find(f"{package.name}-nspkg.pth"):
+        for nspkg_pth_file in self._env.site_packages.find_distribution_nspkg_pth_files(
+            distribution_name=package.name
+        ):
             nspkg_pth_file.unlink()
 
         # If we have a VCS package, remove its source directory

poetry/masonry/builders/editable.py

@@ -61,6 +61,15 @@ def build(self) -> None:
 
             self._run_build_script(self._package.build_script)
 
+        for removed in self._env.site_packages.remove_distribution_files(
+            distribution_name=self._package.name
+        ):
+            self._debug(
+                "  - Removed <c2>{}</c2> directory from <b>{}</b>".format(
+                    removed.name, removed.parent
+                )
+            )
+
         added_files = []
         added_files += self._add_pth()
         added_files += self._add_scripts()
@@ -115,6 +124,16 @@ def _add_pth(self) -> List[Path]:
             content += decode(path + os.linesep)
 
         pth_file = Path(self._module.name).with_suffix(".pth")
+
+        # remove any pre-existing pth files for this package
+        for file in self._env.site_packages.find(path=pth_file, writable_only=True):
+            self._debug(
+                "  - Removing existing <c2>{}</c2> from <b>{}</b> for {}".format(
+                    file.name, file.parent, self._poetry.file.parent
+                )
+            )
+            file.unlink(missing_ok=True)
+
         try:
             pth_file = self._env.site_packages.write_text(
                 pth_file, content, encoding="utf-8"
@@ -199,20 +218,7 @@ def _add_dist_info(self, added_files: List[Path]) -> None:
         added_files = added_files[:]
 
         builder = WheelBuilder(self._poetry)
-
-        dist_info_path = Path(builder.dist_info)
-        for dist_info in self._env.site_packages.find(
-            dist_info_path, writable_only=True
-        ):
-            if dist_info.exists():
-                self._debug(
-                    "  - Removing existing <c2>{}</c2> directory from <b>{}</b>".format(
-                        dist_info.name, dist_info.parent
-                    )
-                )
-                shutil.rmtree(str(dist_info))
-
-        dist_info = self._env.site_packages.mkdir(dist_info_path)
+        dist_info = self._env.site_packages.mkdir(Path(builder.dist_info))
 
         self._debug(
             "  - Adding the <c2>{}</c2> directory to <b>{}</b>".format(

poetry/utils/env.py

@@ -1,5 +1,6 @@
 import base64
 import hashlib
+import itertools
 import json
 import os
 import platform
@@ -12,11 +13,13 @@
 
 from contextlib import contextmanager
 from copy import deepcopy
+from importlib.metadata import PathDistribution
 from pathlib import Path
 from subprocess import CalledProcessError
 from typing import Any
 from typing import ContextManager
 from typing import Dict
+from typing import Iterable
 from typing import Iterator
 from typing import List
 from typing import Optional
@@ -166,7 +169,12 @@ def __init__(
 
         self._fallbacks = fallbacks or []
         self._skip_write_checks = skip_write_checks
-        self._candidates = list({self._purelib, self._platlib}) + self._fallbacks
+
+        self._candidates: List[Path] = []
+        for path in itertools.chain([self._purelib, self._platlib], self._fallbacks):
+            if path not in self._candidates:
+                self._candidates.append(path)
+
         self._writable_candidates = None if not skip_write_checks else self._candidates
 
     @property
@@ -198,7 +206,9 @@ def writable_candidates(self) -> List[Path]:
 
         return self._writable_candidates
 
-    def make_candidates(self, path: Path, writable_only: bool = False) -> List[Path]:
+    def make_candidates(
+        self, path: Path, writable_only: bool = False, strict: bool = False
+    ) -> List[Path]:
         candidates = self._candidates if not writable_only else self.writable_candidates
         if path.is_absolute():
             for candidate in candidates:
@@ -214,7 +224,91 @@ def make_candidates(self, path: Path, writable_only: bool = False) -> List[Path]
                     )
                 )
 
-        return [candidate / path for candidate in candidates if candidate]
+        results = [candidate / path for candidate in candidates if candidate]
+
+        if not results and strict:
+            raise RuntimeError(
+                'Unable to find a suitable destination for "{}" in {}'.format(
+                    str(path), paths_csv(self._candidates)
+                )
+            )
+
+        return results
+
+    def distributions(
+        self, name: Optional[str] = None, writable_only: bool = False
+    ) -> Iterable[PathDistribution]:
+        path = list(
+            map(
+                str, self._candidates if not writable_only else self.writable_candidates
+            )
+        )
+        for distribution in PathDistribution.discover(
+            name=name, path=path
+        ):  # type: PathDistribution
+            yield distribution
+
+    def find_distribution(
+        self, name: str, writable_only: bool = False
+    ) -> Optional[PathDistribution]:
+        for distribution in self.distributions(name=name, writable_only=writable_only):
+            return distribution
+        else:
+            return None
+
+    def find_distribution_files_with_suffix(
+        self, distribution_name: str, suffix: str, writable_only: bool = False
+    ) -> Iterable[Path]:
+        for distribution in self.distributions(
+            name=distribution_name, writable_only=writable_only
+        ):
+            for file in distribution.files:
+                if file.name.endswith(suffix):
+                    yield Path(distribution.locate_file(file))
+
+    def find_distribution_files_with_name(
+        self, distribution_name: str, name: str, writable_only: bool = False
+    ) -> Iterable[Path]:
+        for distribution in self.distributions(
+            name=distribution_name, writable_only=writable_only
+        ):
+            for file in distribution.files:
+                if file.name == name:
+                    yield Path(distribution.locate_file(file))
+
+    def find_distribution_nspkg_pth_files(
+        self, distribution_name: str, writable_only: bool = False
+    ) -> Iterable[Path]:
+        return self.find_distribution_files_with_suffix(
+            distribution_name=distribution_name,
+            suffix="-nspkg.pth",
+            writable_only=writable_only,
+        )
+
+    def find_distribution_direct_url_json_files(
+        self, distribution_name: str, writable_only: bool = False
+    ) -> Iterable[Path]:
+        return self.find_distribution_files_with_name(
+            distribution_name=distribution_name,
+            name="direct_url.json",
+            writable_only=writable_only,
+        )
+
+    def remove_distribution_files(self, distribution_name: str) -> List[Path]:
+        paths = []
+
+        for distribution in self.distributions(
+            name=distribution_name, writable_only=True
+        ):
+            for file in distribution.files:
+                Path(distribution.locate_file(file)).unlink(missing_ok=True)
+
+            if distribution._path.exists():
+                shutil.rmtree(str(distribution._path))
+
+            paths.append(distribution._path)
+
+        return paths
 
     def _path_method_wrapper(
         self,
@@ -228,14 +322,9 @@ def _path_method_wrapper(
         if isinstance(path, str):
             path = Path(path)
 
-        candidates = self.make_candidates(path, writable_only=writable_only)
-
-        if not candidates:
-            raise RuntimeError(
-                'Unable to find a suitable destination for "{}" in {}'.format(
-                    str(path), paths_csv(self._candidates)
-                )
-            )
+        candidates = self.make_candidates(
+            path, writable_only=writable_only, strict=True
+        )
 
         results = []
 
@@ -244,8 +333,7 @@ def _path_method_wrapper(
                 result = candidate, getattr(candidate, method)(*args, **kwargs)
                 if return_first:
                     return result
-                else:
-                    results.append(result)
+                results.append(result)
             except OSError:
                 # TODO: Replace with PermissionError
                 pass
@@ -267,7 +355,11 @@ def exists(self, path: Union[str, Path]) -> bool:
             for value in self._path_method_wrapper(path, "exists", return_first=False)
         )
 
-    def find(self, path: Union[str, Path], writable_only: bool = False) -> List[Path]:
+    def find(
+        self,
+        path: Union[str, Path],
+        writable_only: bool = False,
+    ) -> List[Path]:
         return [
             value[0]
             for value in self._path_method_wrapper(