handle importlib typing at python 3.7

Author: dimbleby

Diff for: pyproject.toml

@@ -127,6 +127,18 @@ module = [
 ]
 ignore_errors = true
 
+# use of importlib-metadata backport at python3.7 makes it impossible to
+# satisfy mypy without some ignores: but we get a different set of ignores at
+# different python versions.
+#
+# <https://github.com/python/mypy/issues/8823>, meanwhile suppress that
+# warning.
+[[tool.mypy.overrides]]
+module = [
+  'poetry.repositories.installed_repository',
+]
+warn_unused_ignores = false
+
 [[tool.mypy.overrides]]
 module = [
   'cachecontrol.*',

Diff for: src/poetry/repositories/installed_repository.py

@@ -163,7 +163,11 @@ def create_package_from_distribution(
             source_reference=source_reference,
             source_resolved_reference=source_resolved_reference,
         )
-        package.description = distribution.metadata.get("summary", "")
+
+        package.description = distribution.metadata.get(  # type: ignore[attr-defined]
+            "summary",
+            "",
+        )
 
         return package
 
@@ -213,7 +217,10 @@ def create_package_from_pep610(cls, distribution: metadata.Distribution) -> Pack
             develop=develop,
         )
 
-        package.description = distribution.metadata.get("summary", "")
+        package.description = distribution.metadata.get(  # type: ignore[attr-defined]
+            "summary",
+            "",
+        )
 
         return package
 
@@ -229,7 +236,9 @@ def load(cls, env: Env, with_dependencies: bool = False) -> InstalledRepository:
 
         for entry in reversed(env.sys_path):
             for distribution in sorted(
-                metadata.distributions(path=[entry]),
+                metadata.distributions(  # type: ignore[no-untyped-call]
+                    path=[entry],
+                ),
                 key=lambda d: str(d._path),  # type: ignore[attr-defined]
             ):
                 name = canonicalize_name(distribution.metadata["name"])