fix(kotlin): link extensions through imported receiver aliases

CHANGELOG.md

@@ -19,6 +19,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixes
 
+- In Kotlin, calls to an extension on an imported type now find it when its receiver is written with an import alias, even when the declaration and caller use different aliases; an alias for a different type is still kept apart. Re-index Kotlin projects after upgrading.
 - In TypeScript, an awaited call with type arguments like `await fetchApi<User>("/me")` or `await api.get<T>(url)` now links to the function it calls. Before, the call was dropped, so typed fetch wrappers looked like they had no callers. (#2586)
 - In JavaScript and TypeScript, a call or `new` in a parameter's default value, like `function renderWithNote(note = buildNote())`, a destructured `{ size = defaultSize() }` or `constructor(private svc = new Service())`, now counts as the function's own call. Before, it was dropped, so `buildNote` was missing that caller and impact on it came back incomplete. Re-index JavaScript and TypeScript projects after upgrading. Thanks @inth3shadows for the report and the pull request. (#2588)
 - In React, a component rendered at module scope, in a top-level constant or inside a test's `it(…)` callback, like `createRoot(el).render(<App />)` or `render(<Card />)`, now counts as rendered there, so an app's entry reaches its root component and a component's tests show among its callers. (#2587)

__tests__/kotlin-extension-import-alias.test.ts

@@ -0,0 +1,76 @@
+import { describe, expect, it } from 'vitest';
+import * as fs from 'fs';
+import * as os from 'os';
+import * as path from 'path';
+import CodeGraph from '../src/index';
+
+describe('Kotlin extension receiver import aliases', () => {
+  it('retains an aliased library extension without accepting the same alias for another type', async () => {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-kotlin-import-alias-'));
+    let cg: CodeGraph | undefined;
+    try {
+      for (const [file, source] of Object.entries({
+        'p/Foreign.kt': `package p
+import javax.lang.model.element.Modifier as LayoutModifier
+import androidx.compose.ui.Modifier as UnusedCompose
+fun LayoutModifier.keyword() {}`,
+        'q/Calls.kt': `package q
+import androidx.compose.ui.Modifier as LayoutModifier
+import p.keyword
+fun LayoutModifier.pad() {}
+fun caller() {
+    LayoutModifier.pad()
+    LayoutModifier.keyword()
+}`,
+      })) {
+        const target = path.join(dir, file);
+        fs.mkdirSync(path.dirname(target), { recursive: true });
+        fs.writeFileSync(target, source);
+      }
+      cg = CodeGraph.initSync(dir);
+      await cg.indexAll();
+      const caller = cg.searchNodes('caller').map(r => r.node).find(n => n.name === 'caller')!;
+      expect(cg.getCallees(caller.id).filter(c => c.edge.kind === 'calls').map(c => c.node.qualifiedName))
+        .toEqual(['LayoutModifier::pad']);
+    } finally {
+      cg?.destroy();
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+  it.each([
+    ['Modifier', 'CallAlias'],
+    ['DeclAlias', 'Modifier'],
+    ['DeclAlias', 'CallAlias'],
+    ['SameAlias', 'SameAlias'],
+  ])('links a receiver declared as %s and called as %s', async (declared, called) => {
+    const dir = fs.mkdtempSync(path.join(os.tmpdir(), 'cg-kotlin-alias-'));
+    let cg: CodeGraph | undefined;
+    const typeImport = (alias: string) => 'import androidx.compose.ui.Modifier' + (alias === 'Modifier' ? '' : ` as ${alias}`);
+    try {
+      const files = {
+        'extensions/Extensions.kt': `package extensions\n${typeImport(declared)}\nfun ${declared}.pad() {}`,
+        'decoy/Extensions.kt': `package decoy\nimport javax.lang.model.element.Modifier as ${declared}\nfun ${declared}.pad() {}`,
+        'caller/Calls.kt': `package caller\n${typeImport(called)}\nimport extensions.pad\nfun caller() { ${called}.pad() }`,
+        'unimported/Calls.kt': `package unimported\n${typeImport(called)}\nfun hidden() { ${called}.pad() }`,
+      };
+      for (const [file, source] of Object.entries(files)) {
+        const target = path.join(dir, file);
+        fs.mkdirSync(path.dirname(target), { recursive: true });
+        fs.writeFileSync(target, source);
+      }
+      cg = CodeGraph.initSync(dir);
+      await cg.indexAll();
+      const calls = (name: string) => {
+        const caller = cg!.getNodesByName(name).find(n => n.kind === 'function')!;
+        return cg!.getCallees(caller.id).filter(c => c.edge.kind === 'calls').map(c => c.node.filePath);
+      };
+      expect(calls('caller')).toEqual(['extensions/Extensions.kt']);
+      expect(calls('hidden')).toEqual([]);
+    } finally {
+      cg?.destroy();
+      fs.rmSync(dir, { recursive: true, force: true });
+    }
+  });
+
+});

src/resolution/name-matcher.ts

@@ -2367,10 +2367,14 @@ function kotlinExtensionOnImportedType(ref: UnresolvedRef, context: ResolutionCo
   const binding = context.getImportMappings(ref.filePath, ref.language).find((m) => m.localName === call[1]);
   if (!binding) return null;
   const pkg = binding.source.slice(0, binding.source.lastIndexOf('.'));
-  const extensions = context.getNodesByQualifiedName(`${binding.exportedName}::${call[2]}`).filter((n) => {
-    if (n.kind !== 'method' || n.language !== 'kotlin' || !isKotlinTopLevelVisible(n, ref, context)) return false;
-    const scope = kotlinFileScope(n.filePath, context);
-    return scope.imports.has(binding.source) || scope.stars.has(pkg);
+  const extensions = context.getNodesByName(call[2]!).filter((n) => {
+    if (n.kind !== 'method' || n.language !== 'kotlin') return false;
+    // Each file may spell the same imported receiver with a different alias.
+    const receiver = n.qualifiedName.slice(0, n.qualifiedName.lastIndexOf('::'));
+    const declared = context.getImportMappings(n.filePath, 'kotlin').find((m) => m.localName === receiver);
+    const sameType = declared ? declared.source === binding.source
+      : receiver === binding.exportedName && kotlinFileScope(n.filePath, context).stars.has(pkg);
+    return sameType && isKotlinTopLevelVisible(n, ref, context);
   });
   const chosen = extensions.length > 1 ? extensions.filter((n) => n.filePath === ref.filePath) : extensions;
   return chosen.length === 1 ? { original: ref, targetNodeId: chosen[0]!.id, confidence: 0.9, resolvedBy: 'qualified-name' } : null;