fix(resolution): read a quoted Python annotation as a receiver type

CHANGELOG.md

@@ -201,6 +201,8 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 #### Symbols, tests and the viewer
 
+- Python parameters annotated with a quoted forward reference — `def f(o: "Alpha")`, or anything under `from __future__ import annotations` — now resolve the methods called on them, the same as the unquoted annotation. Re-index Python projects after upgrading. (#1684)
+
 - **Files under an `e2e/` directory count as tests.** Their calls no longer appear as production callers in Steps, dead-code and test badges.
 
 - **Production code under a `samples` or `examples` package path is no longer treated as test code.** A Kotlin or Java project whose package path runs through `com/google/samples/…` (Now in Android, for one) had nearly every file counted as a fixture, so the Map opened on `build-logic`, the entry points hid the app, and dead-code and test badges were wrong. Only the project layout above a `src/` folder decides now; the package path below it never does.

__tests__/python-quoted-annotation.test.ts

@@ -0,0 +1,55 @@
+/**
+ * A quoted (forward-reference) parameter annotation names a receiver type too
+ * (#1684): `def f(o: "Alpha")` resolves `o.render()` exactly like `def f(o:
+ * Alpha)`. Quoted annotations are ordinary Python — forward references, and
+ * everything under `from __future__ import annotations`.
+ */
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import { CodeGraph } from '../src';
+import { initGrammars, loadAllGrammars } from '../src/extraction/grammars';
+
+let dir: string;
+let cg: CodeGraph;
+
+beforeAll(async () => {
+  await initGrammars();
+  await loadAllGrammars();
+  dir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-1684-'));
+  fs.mkdirSync(path.join(dir, 'pkg'));
+  fs.writeFileSync(path.join(dir, 'pkg', '__init__.py'), '');
+  fs.writeFileSync(
+    path.join(dir, 'pkg', 'a.py'),
+    'def render(x):\n    return x\n\nclass Alpha:\n    def render(self):\n        return "a"\n\nclass Beta:\n    def render(self):\n        return "b"\n'
+  );
+  fs.writeFileSync(
+    path.join(dir, 'pkg', 'b.py'),
+    'from __future__ import annotations\nfrom pkg.a import Alpha, Beta\n\n' +
+      'def quoted(o: "Alpha"):\n    return o.render()\n\n' +
+      "def single_quoted(o: 'Beta'):\n    return o.render()\n\n" +
+      'def unquoted(o: Alpha):\n    return o.render()\n'
+  );
+  cg = CodeGraph.initSync(dir);
+  await cg.indexAll();
+});
+
+afterAll(() => {
+  cg.destroy();
+  fs.rmSync(dir, { recursive: true, force: true });
+});
+
+const calleeOf = (fn: string): string[] =>
+  cg
+    .getCallees(cg.getNodesByName(fn).find((n) => n.kind === 'function')!.id)
+    .map(({ node }) => node.qualifiedName)
+    .sort();
+
+describe('quoted forward-reference annotations (#1684)', () => {
+  it('resolves the method on the quoted type, the same as the unquoted annotation', () => {
+    expect(calleeOf('unquoted')).toEqual(['Alpha::render']);
+    expect(calleeOf('quoted')).toEqual(['Alpha::render']);
+    expect(calleeOf('single_quoted')).toEqual(['Beta::render']);
+  });
+});

src/resolution/name-matcher.ts

@@ -1338,6 +1338,12 @@ function buildLocalReceiverTypePatterns(language: Language, r: string): RegExp[]
     case 'python':
       return [
         new RegExp(`\\b${r}\\b\\s*=\\s*([A-Z][\\w.]*)\\s*\\(`), // lg = Logger(...)
+        // A quoted forward reference (`lg: "Logger"`, `lg: 'pkg.Logger'`) is the
+        // same annotation — and what every file under `from __future__ import
+        // annotations` or with a not-yet-defined class writes. The unquoted
+        // pattern below stopped at the quote and read no type at all, so the
+        // call produced no edge (#1684). Tried first: it is the stricter shape.
+        new RegExp(`\\b${r}\\b\\s*:\\s*["']([A-Z][\\w.]*)["']`), // lg: "Logger"
         new RegExp(`\\b${r}\\b\\s*:\\s*([A-Z][\\w.]*)`), // lg: Logger  (PEP 526)
       ];
     case 'java':