fix(python): a base's type argument is no supertype, so Repo.save() is not User.save

CHANGELOG.md

@@ -30,6 +30,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - In Python, `from app import email` no longer links the importing file to a project variable named `app`, such as a FastAPI or Flask `app = FastAPI()`. (#2584)
 - In Python, a from-import of a module whose name has no dot, like `from loader import Registry` with `loader.py` at the repository root, or `from mypackage import helper` in a `src/` layout, now links the importing file to that module's file, as `import loader` and `from pkg.loader import Registry` already did. Before, the file's dependency on the module itself was left out, so `codegraph affected` and impact could miss the files that import it. When the file also imported something else under the module's name, like `from django.core import mail` beside `from mail import …`, the module was linked to that instead. Re-index Python projects after upgrading.
 - In Python, a call through a module-level instance, like `_svc.delete(obj)` after `_svc = SceneService()`, now links to the method its class has or inherits, even when other classes have a method of that name. (#2582)
+- In Python, a call on a class or on a receiver named after it, like `Repo.save()` or `repo.save()` with `class Repo(Base[User])`, no longer links to a method of the base's type argument, like `User.save`. Before, every name in the base list counted as a supertype, so `User` was searched as if `Repo` inherited from it. The base itself, `Base`, is still searched. Re-index Python projects after upgrading. Thanks @JosefAschauer.
 - In Python, a call of your own class's method named like a dictionary, list or file method, such as `get`, `update`, `items`, `pop` or `close`, now links to that method when the function says what the variable holds: `reg = SystemPackRegistry()` then `reg.get(…)`, `registry = load_registry()` with `def load_registry() -> SystemPackRegistry`, or a parameter written `reg: SystemPackRegistry`. Before, these calls were dropped as built-in methods unless the variable was named after the class. A variable the function also sets to something else, like `{}` or what `json.load` returns, a class imported from another package, like `queue.Queue`, and a union type still link nothing. Re-index Python projects after upgrading. Thanks @inth3shadows for the report. (#2583)
 - In Python, Scala and Java, a standard-library method called on a value whose type CodeGraph can't see, like `options.setdefault(…)` on a dictionary, `m.getOrElse(…)` on an `Option` or `data.put(…)` on a map held in a `var`, no longer links to an unrelated project method that happens to share its name; the call still links when the variable is named after your class, like `registry.get(…)` for a `Registry`. Re-index Python, Scala and Java projects after upgrading. Thanks @danusha2345. (#1947)
 - In Python, a call on a module imported from outside your project, like `subprocess.run(…)` after `import subprocess`, no longer links to a project method that happens to share its name. Thanks @Egrn for the report. (#2599)

__tests__/python-supertype-type-arguments.test.ts

@@ -0,0 +1,136 @@
+/**
+ * A Python class's supertypes, as its head declares them, are the classes its
+ * bases name — not their type arguments. `class Repo(Base[User])` extends
+ * `Base`; reading every word of the base list also counted `User`, so a call on
+ * the class or on a receiver named after it, `Repo.save()` / `repo.save()`,
+ * reached `User.save` when `Base` declares no `save`.
+ */
+import { describe, it, expect, afterAll, beforeAll } from 'vitest';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { CodeGraph } from '../src';
+
+let root = '';
+let cg: CodeGraph;
+
+beforeAll(async () => {
+  root = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-py-supertype-type-args-'));
+  fs.mkdirSync(path.join(root, 'app'));
+  fs.writeFileSync(path.join(root, 'app/__init__.py'), '');
+  fs.writeFileSync(path.join(root, 'app/m.py'), `from typing import Generic, Optional, TypeVar
+
+T = TypeVar("T")
+U = TypeVar("U")
+
+
+class Base(Generic[T]):
+    def load(self):
+        pass
+
+
+class Pair(Generic[T, U]):
+    def load(self):
+        pass
+
+
+class User:
+    def save(self):
+        pass
+
+
+class Other:
+    def save(self):
+        pass
+
+
+class Repo(Base[User]):
+    pass
+
+
+class Store(Pair[str, dict[str, User]]):
+    pass
+
+
+class Keyed(Base[User], metaclass=type):
+    pass
+
+
+class Forward(Base["Pair[str, User]"]):
+    pass
+
+
+class Mixin:
+    def save(self):
+        pass
+
+
+class Mixed(Base[Optional[User]], Mixin):
+    pass
+
+
+def save_by_class():
+    Repo.save()
+
+
+def save_by_receiver(repo):
+    repo.save()
+
+
+def save_nested():
+    Store.save()
+
+
+def save_keyed():
+    Keyed.save()
+
+
+def save_forward():
+    Forward.save()
+
+
+def save_mixed():
+    Mixed.save()
+
+
+def load_by_class():
+    Repo.load()
+
+
+def load_nested():
+    Store.load()
+`);
+  cg = await CodeGraph.init(root, { index: true });
+});
+
+afterAll(() => {
+  cg?.close();
+  if (root) fs.rmSync(root, { recursive: true, force: true });
+});
+
+/** Qualified names of the methods `fn` calls. */
+const calls = (fn: string): string[] => {
+  const node = cg.getNodesInFile('app/m.py').find((n) => n.name === fn && n.kind === 'function')!;
+  expect(node, fn).toBeDefined();
+  return cg.getOutgoingEdges(node.id).filter((e) => e.kind === 'calls')
+    .map((e) => cg.getNode(e.target)!).filter((n) => n.kind === 'method').map((n) => n.qualifiedName);
+};
+
+describe('a Python type argument is no supertype', () => {
+  it('does not reach a method of the type argument', () => {
+    expect(calls('save_by_class')).not.toContain('User::save');
+    expect(calls('save_by_receiver')).not.toContain('User::save');
+    expect(calls('save_nested')).not.toContain('User::save');
+    expect(calls('save_keyed')).not.toContain('User::save');
+    expect(calls('save_forward')).not.toContain('User::save');
+  });
+
+  it('still reaches the method the base declares', () => {
+    expect(calls('load_by_class')).toEqual(['Base::load']);
+    expect(calls('load_nested')).toEqual(['Pair::load']);
+  });
+
+  it('reaches a later base past the type argument that came first', () => {
+    expect(calls('save_mixed')).toEqual(['Mixin::save']);
+  });
+});

src/resolution/name-matcher.ts

@@ -21514,8 +21514,12 @@ function readDeclaredSupertypes(cls: Node, context: ResolutionContext): string[]
     // A base built by a class's factory — Django's `class Manager(
     // BaseManager.from_queryset(QuerySet))` — subclasses that class: the
     // qualifier is the supertype, not the method called on it.
-    case 'python': return names(/\bclass\s+\w+\s*\(([^)]*)\)/.exec(head)?.[1]?.replace(/\w+\s*=\s*[\w.]+/g, '')
-      .replace(/([A-Za-z_][\w.]*)\.\w+\s*\(/g, '$1 ('));
+    // A parameterized base, `Base[User]`, is `Base`: its type arguments are no supertypes.
+    case 'python': {
+      let bases = /\bclass\s+\w+\s*\(([^)]*)\)/.exec(head)?.[1];
+      while (bases && /\[[^[\]]*\]/.test(bases)) bases = bases.replace(/\[[^[\]]*\]/g, '');
+      return names(bases?.replace(/\w+\s*=\s*[\w.]+/g, '').replace(/([A-Za-z_][\w.]*)\.\w+\s*\(/g, '$1 ('));
+    }
     case 'ruby': return names(/\bclass\s+[\w:]+\s*<\s*([\w:]+)/.exec(head)?.[1]);
     case 'php': return names(/\bextends\s+([\w.\\]+)/.exec(head)?.[1]);
     case 'typescript': case 'tsx': case 'javascript': case 'jsx':