fix(python): a class with PEP 695 type parameters reads its base list

CHANGELOG.md

@@ -44,6 +44,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - 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 class with a parameterized base, like `class Leaf(Base[str])`, `class Repo(models.Base[int])` or `class Both(Mixin, Base[str])`, is now linked to that base, as `class Leaf(Base)` already was, and a call through a module global holding such a class, like `current = Leaf()` then `current.run()`, reaches the method the base declares. Before, such a base was skipped, so the class had no `extends` edge and anything that follows the class hierarchy missed it. Re-index Python projects after upgrading. Thanks @JosefAschauer.
 - In Python, a class whose base list is wrapped over several lines, as black and ruff write a long one, now reaches the methods its bases declare, through a module global like `current = Wrapped()` then `current.run()` and through the class name like `Wrapped.run(x)`, as a one-line base list already did. Before, only the first line or three were read for this, so such a class seemed to have no bases. Re-index Python projects after upgrading. Thanks @JosefAschauer.
+- In Python, a class written with PEP 695 type parameters, like `class Repo[T](Base[T]):` or `class Pair[K, V: (int, str)](Base[V]):`, now reaches the methods its bases declare, through a module global and through the class name, as a class without type parameters already did. Before, the type parameter list stood where the base list was expected, so such a class seemed to have no bases there, although its `extends` edge was already right. Re-index Python projects after upgrading.
 - 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-pep695-bases.test.ts

@@ -0,0 +1,171 @@
+/**
+ * A Python class with PEP 695 type parameters, `class Repo[T](Base[T]):`,
+ * names its bases after the parameter list. The resolver's base-list reader
+ * (`pythonBaseList`, behind module-global, `self.` and class-name dispatch)
+ * expected `(` right after the name, so such a class had no bases there.
+ */
+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-pep695-bases-'));
+  fs.mkdirSync(path.join(root, 'app'));
+  fs.writeFileSync(path.join(root, 'app/__init__.py'), '');
+  fs.writeFileSync(path.join(root, 'app/m.py'), `class Base[T]:
+    def run(self):
+        pass
+
+
+class Other:
+    def run(self):
+        pass
+
+
+class Mixin:
+    pass
+
+
+class Classic(Mixin, Base):
+    pass
+
+
+class Repo[T](Base[T]):
+    pass
+
+
+class Bounded[T: dict[str, int], *Ts, **P](Mixin, Base[T]):
+    pass
+
+
+class Constrained[T: (int, str)](Mixin, Base[T]):
+    pass
+
+
+class WrappedParams[
+    K,
+    V: (int, str),
+](
+    Mixin,
+    Base[V],
+):
+    pass
+
+
+class NoBases[T]:
+    pass
+
+
+current_a = Classic()
+current_b = Repo()
+current_c = Bounded()
+current_d = Constrained()
+current_e = WrappedParams()
+
+
+def global_classic():
+    current_a.run()
+
+
+def global_repo():
+    current_b.run()
+
+
+def global_bounded():
+    current_c.run()
+
+
+def global_constrained():
+    current_d.run()
+
+
+def global_wrapped_params():
+    current_e.run()
+
+
+def class_classic(x):
+    Classic.run(x)
+
+
+def class_repo(x):
+    Repo.run(x)
+
+
+def class_bounded(x):
+    Bounded.run(x)
+
+
+def class_constrained(x):
+    Constrained.run(x)
+
+
+def class_wrapped_params(x):
+    WrappedParams.run(x)
+
+
+def class_no_bases(x):
+    NoBases.run(x)
+`);
+  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);
+};
+
+// Base and Other both declare `run`, and the globals are not named after their
+// classes, so only the class's own bases can pick one.
+describe('a Python class with PEP 695 type parameters', () => {
+  it('resolves through a classic base list (control)', () => {
+    expect(calls('global_classic')).toEqual(['Base::run']);
+    expect(calls('class_classic')).toEqual(['Base::run']);
+  });
+
+  it('reads the bases after a type parameter list', () => {
+    expect(calls('global_repo')).toEqual(['Base::run']);
+    expect(calls('class_repo')).toEqual(['Base::run']);
+  });
+
+  it('skips bounds with brackets, *Ts and **P in the parameter list', () => {
+    expect(calls('global_bounded')).toEqual(['Base::run']);
+    expect(calls('class_bounded')).toEqual(['Base::run']);
+  });
+
+  it('does not take a constraint tuple for the base list', () => {
+    expect(calls('global_constrained')).toEqual(['Base::run']);
+    expect(calls('class_constrained')).toEqual(['Base::run']);
+  });
+
+  it('reads a parameter list and a base list both wrapped over several lines', () => {
+    expect(calls('global_wrapped_params')).toEqual(['Base::run']);
+    expect(calls('class_wrapped_params')).toEqual(['Base::run']);
+  });
+
+  it('links each such class to its base with an extends edge', () => {
+    const base = cg.getNodesInFile('app/m.py').find((n) => n.name === 'Base' && n.kind === 'class')!;
+    for (const name of ['Repo', 'Bounded', 'Constrained', 'WrappedParams']) {
+      const cls = cg.getNodesInFile('app/m.py').find((n) => n.name === name && n.kind === 'class')!;
+      const targets = cg.getOutgoingEdges(cls.id).filter((e) => e.kind === 'extends').map((e) => e.target);
+      expect(targets, name).toContain(base.id);
+    }
+  });
+
+  it('gives a parameterized class without bases none', () => {
+    expect(calls('class_no_bases')).not.toContain('Base::run');
+    expect(calls('class_no_bases')).not.toContain('Other::run');
+  });
+});

src/resolution/name-matcher.ts

@@ -414,21 +414,33 @@ function pythonRefClass(name: string, ref: UnresolvedRef, context: ResolutionCon
  * A Python class's base list as written, up to its closing parenthesis, which
  * may be lines below the `class` line: black and ruff wrap a long list one base
  * per line. Comments in it are left out. Undefined for a class without one.
+ * A PEP 695 type parameter list between the name and the bases, `class
+ * Repo[T: (int, str)](Base[T]):`, is skipped whole, wrapped or not, so a
+ * constraint tuple in it is not taken for the base list.
  */
 function pythonBaseList(cls: Node, context: ResolutionContext): string | undefined {
   const lines = context.getFileLines?.(cls.filePath) ?? context.readFile(cls.filePath)?.split(/\r?\n/) ?? [];
-  const head = /^\s*class\s+\w+\s*\(/.exec(lines[cls.startLine - 1] ?? '');
+  const head = /^\s*class\s+\w+/.exec(lines[cls.startLine - 1] ?? '');
   if (!head) return undefined;
   let list = '';
-  let depth = 1;
+  let depth = 0;
+  let params = 0;
   for (let i = cls.startLine - 1; i < Math.max(cls.endLine, cls.startLine); i++) {
     const text = (i === cls.startLine - 1 ? lines[i]!.slice(head[0].length) : lines[i] ?? '').replace(/#.*$/, '');
     for (const ch of text) {
+      if (depth === 0) {
+        if (ch === '[') params++;
+        else if (ch === ']') params--;
+        else if (params === 0 && ch === '(') depth = 1;
+        // Anything else after the name and its parameters, such as `:`, means no base list.
+        else if (params === 0 && !/\s/.test(ch)) return undefined;
+        continue;
+      }
       if (ch === '(') depth++;
       else if (ch === ')' && --depth === 0) return list;
       list += ch;
     }
-    list += ' ';
+    if (depth > 0) list += ' ';
   }
   return undefined;
 }