fix(kotlin): a private property, and the members of a private class, stay in their file

A Kotlin property was indexed without its visibility modifier, so the
Kotlin file-local rule (#1745), which declines a private fun in another
file, read every property as public: a call like token(...) could link
to another file's @Volatile private var token, and JavaScript, Go or
Python callers to a Kotlin test fixture's private val. A public member
of a private class or object was reachable from other files too, though
nothing outside its file can name it.

Both extractors (wasm and the native kernel) now read a property's
modifiers the way they read a function's, and a candidate inside a
private Kotlin class or object is declined from another file. That
second rule is Kotlin's alone: a Scala private[pkg] class, or one with
a private constructor, is its package's, and a C# private nested class
serves every file of its partial class. Applied to every language where
private is file-local, as the PR had it, it removed 742 edges on http4s
(right ones among them, like stream.receiveHeaders() on a private[h2]
class H2Stream), 91 on scalachess and 10 on serilog (9 of them right
typed edges).

Validation:
- cross-file-visibility.test.ts: 2 cases, red on main, green here; the
  kernel parity fixture gains a private val and an internal var.
- Kernel parity (kotlin), 0 diffs: okhttp 588/619 files, mihon 891/940,
  nowinandroid 340/350, SystemUI's Kotlin 188/198 byte-identical, the
  same files deferred to wasm as with main's kernel; torture 1/1.
- A/B against main 01e0ac3a (with the Kotlin receiver typing of #1933):
  okhttp -274, mihon -177, SystemUI -94, every one a call from another
  file onto a private Kotlin property or a member of a private class or
  object (okhttp's private inner AndroidQuery.enqueue and
  RealWebSocketTest's private TestStreams, mihon's private IntentFilter
  filter that collections' filter { } reached, SystemUI's private
  MyExecutor.execute); nothing added. nowinandroid, jextract, click and
  gin identical; against main 4eb8c2a5, http4s, scalachess and serilog
  were identical too.
- Cost (mihon, median of 3 interleaved indexes, on main 4eb8c2a5): CPU
  25.7 s on main vs 25.5 s, wall 8.2 s on both.

Original PR #1761 by @danusha2345.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -255,6 +255,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - In Kotlin, a call on what one of your functions returns, like `repository().pending(1)` or `val repo = repository(); repo.pending(1)` with a `private fun repository(): RealRepo` in a test class, now links to the method of the type that function declares, including one the type inherits or an extension on it. Before, the chained call went to whichever `pending` the name matched first, like a test double's in another package, and the local was guessed from its name, which reached the interface. The function is found in the calling class, a class it inherits from or one around it, or at the top level, and a nested type like `Request.Builder` is that type, not another class's `Builder`. When the declared type has no such method, the call now links to nothing rather than a method of the same name elsewhere; a type from outside your project is matched by name as before. Re-index Kotlin projects after upgrading. Thanks @mindcipherrr for the report. (#2805)
 - In Kotlin, a call through a property now links to the method of the type the property is declared with, like `server.enqueue(…)` on a `lateinit var server: MockWebServer` or a call on a constructor property such as `class A(private val repo: Repo)`. So does a call through a chain like `engine.pump.drain()` or `Mode.ON.next()`, through a property one of your classes inherits, through a local set from a call like `val lease = HardwareLock.tryBegin()`, and through a local of the function around an anonymous `object : …`. Before, such a call went to an interface's method or to whichever method had the name: on okhttp, the tests' calls reached the deprecated `MockWebServer` instead of the one each file imports. A call on a type from outside your project, like `Regex` or a JDK class, no longer links to a same-named method of your own, unless your project extends that type with it. Re-index Kotlin projects after upgrading. Thanks @danusha2345.
 - In Kotlin, a `fun interface` is now indexed as an interface with its methods, like okhttp's `HttpLoggingInterceptor.Logger`. Before, it was read as a broken function, and when a comment followed it, the declaration after it went missing too, its members turning into loose functions. Re-index Kotlin projects after upgrading. Thanks @danusha2345.
+- In Kotlin, a `private val` or `private var` property, and the members of a `private` class or object, no longer take calls from other files. Properties were indexed without their visibility, so a call like `token(...)` in one file could link to another class's `private var token`, and JavaScript, Go or Python callers could land on a Kotlin test's private property; a call to `now()` could also land on a method of a test's `private class Clock`. Re-index Kotlin projects after upgrading. Thanks @danusha2345.
 - In JavaScript and TypeScript, a `super.run()` call now links to the method of the class's parent, or of the nearest ancestor that has it, like three.js's `super.copy(source)` reaching `Object3D.copy`, so `codegraph_explore`'s call path and impact follow an override into the method it builds on. Before, such a call inside a method of the same name was dropped, and elsewhere it went to whatever method had the name, often the class's own or a sibling class's in the same file. A call from a static method reaches the parent's static method, and a call to a parent from outside your project, like `HTMLElement`, `Set` or `Promise`, links nothing. Re-index JavaScript and TypeScript projects after upgrading. Thanks @Puma7 for the report and the pull request. (#2497)
 - In JavaScript and TypeScript, a named class expression, like `register(class Widget extends Base {…})`, `customElements.define('x-card', class XCard extends HTMLElement {…})` or `const Panel = class PanelImpl extends Base {…}`, is now indexed as a class with its own methods and the class it extends, so calls between its methods and its `super` calls link as a class declaration's do. Before, its methods were free functions or weren't indexed at all, and it extended nothing. Its name stays bound inside the expression alone, as JavaScript has it: `new Widget()` elsewhere links nothing, a constant, class or interface of the same name around it keeps its links, and code outside never reaches its methods by a guess. A class a CommonJS module exports, like webpack's `module.exports = class MultiCompiler {…}` or `exports.Store = class Store {…}`, is reached through `require` as a class declaration is, along with its static methods and the methods called on its instances. Re-index JavaScript and TypeScript projects after upgrading. Thanks @Puma7 for the report and the pull request. (#2499)
 - In Go, a call through a struct field that holds a function, like prometheus's `d.refreshf(ctx)`, now reaches the functions put in that field, so `codegraph_explore` follows service discovery from `Discovery.Run` into each provider's `refresh` and names the line where each provider wires its method in, like `RefreshF: d.refresh`. The field can be set in a struct literal or by an assignment, copied from another struct's field (`refreshf: opts.RefreshF`), or given a method of an interface value, and two unrelated structs with a field of the same name, like `fn` or `handler`, stay apart. Before, such a flow stopped at the field. Re-index Go projects after upgrading.

__tests__/cross-file-visibility.test.ts

@@ -96,6 +96,31 @@ describe('Kotlin: a private function is class- or file-local', () => {
   });
 });
 
+describe('Kotlin: a private property is class- or file-local too', () => {
+  it('records the modifier on the property and declines a call onto it from another file', async () => {
+    project({
+      'WebRtcTransport.kt': 'class WebRtcTransport {\n    @Volatile private var token = ""\n    internal val shared = 1\n}\n',
+      'CommandValidator.kt': 'class CommandValidator {\n    fun validate(command: Map<String, Any>): String? {\n        if (!token(command["sessionId"], 128)) return "bad"\n        return null\n    }\n}\n',
+    });
+    expect(await calleesOf('validate')).not.toContain('WebRtcTransport.kt:token');
+    const fields = cg!.getNodesByKind('field').filter((n) => n.filePath.endsWith('WebRtcTransport.kt'));
+    expect(fields.find((n) => n.name === 'token')?.visibility).toBe('private');
+    expect(fields.find((n) => n.name === 'shared')?.visibility).toBe('internal');
+  });
+});
+
+describe('Kotlin: a member of a private class is not visible either', () => {
+  it('declines a call onto a public fun of another file\'s private class', async () => {
+    // `clock`'s type is unknown here, so only the method name picks a target.
+    // Not a test file: production code never reaches a test suite's symbol anyway.
+    project({
+      'Coordinator.kt': 'class Coordinator {\n    private class Clock(var value: Long) { fun now() = value }\n}\n',
+      'Gimbal.kt': 'class Gimbal {\n    fun dispatchSpeed() {\n        val clock = provide()\n        val timestamp = clock.now()\n    }\n}\n',
+    });
+    expect(await calleesOf('dispatchSpeed')).not.toContain('Coordinator.kt:now');
+  });
+});
+
 describe('Go: an unexported identifier is package-local', () => {
   it('does not resolve a call onto an unexported func in another package', async () => {
     project({

__tests__/fixtures/kernel-parity/torture.kt

@@ -26,6 +26,9 @@ fun com.example.Qualified.qext() {}
 suspend fun suspender(): Unit { helper() }
 
 private internal fun visFn() {}
+private val hiddenTop = 1
+internal var sharedTop = 2
+
 
 fun inferred() = helper()
 

codegraph-kernel/src/kotlin.rs

@@ -806,9 +806,11 @@ impl<'t> Walker<'t> {
             return Some(Vec::new());
         };
         // The `type`-field signature read is dead (zero fields) → signature
-        // undefined; NO docstring/visibility/isStatic — the modifiers merge in
-        // create_node still decorates expect/actual properties.
-        let row = self.create_node(kind, &name, node, Extra::default());
+        // undefined; NO docstring/isStatic — the modifiers merge in
+        // create_node still decorates expect/actual properties. Visibility IS
+        // read: a `private val` is file-local to the resolver (#1731).
+        let extra = Extra { visibility: Some(self.visibility_of(node)), ..Extra::default() };
+        let row = self.create_node(kind, &name, node, extra);
         // Walk the initializer ATTRIBUTED to the declared symbol (#693, the Go
         // fix, ported): without this the subtree is only fn-ref-scanned, so a
         // lambda / SAM / object initializer (`val cb = Runnable { target() }` —

src/extraction/languages/kotlin.ts

@@ -2,6 +2,21 @@ import type { Node as SyntaxNode } from 'web-tree-sitter';
 import { getNodeText } from '../tree-sitter-helpers';
 import type { LanguageExtractor } from '../tree-sitter-types';
 
+/** The visibility a Kotlin declaration's `modifiers` child spells out; public by default. */
+function kotlinVisibility(node: { childCount: number; child(i: number): { type: string; text: string } | null }): 'public' | 'private' | 'protected' | 'internal' {
+  for (let i = 0; i < node.childCount; i++) {
+    const child = node.child(i);
+    if (child?.type === 'modifiers') {
+      const text = child.text;
+      if (text.includes('public')) return 'public';
+      if (text.includes('private')) return 'private';
+      if (text.includes('protected')) return 'protected';
+      if (text.includes('internal')) return 'internal';
+    }
+  }
+  return 'public';
+}
+
 /** Kotlin return types that can't be a chained-call receiver (no class to chain on). */
 const KOTLIN_NON_CLASS_RETURN = new Set(['Unit', 'Nothing']);
 
@@ -300,7 +315,10 @@ export const kotlinExtractor: LanguageExtractor = {
       const sig = typeNode
         ? `${isVal ? 'val' : 'var'} ${name}: ${getNodeText(typeNode, ctx.source)}`
         : undefined;
-      const created = ctx.createNode(kind, name, node, { signature: sig });
+      // `private val` / `internal var` at class or object scope: the modifier
+      // decides who can name it from another file (#1731's Kotlin rule reads
+      // `visibility`, and a property without one read as public).
+      const created = ctx.createNode(kind, name, node, { signature: sig, visibility: kotlinVisibility(node) });
       // Walk the initializer ATTRIBUTED to the declared symbol (#693, the Go
       // fix, ported to Kotlin): the hook consumes this subtree, so without an
       // explicit walk a lambda / SAM / object initializer
@@ -504,20 +522,7 @@ export const kotlinExtractor: LanguageExtractor = {
     }
     return sig;
   },
-  getVisibility: (node) => {
-    // Check for visibility modifiers in Kotlin
-    for (let i = 0; i < node.childCount; i++) {
-      const child = node.child(i);
-      if (child?.type === 'modifiers') {
-        const text = child.text;
-        if (text.includes('public')) return 'public';
-        if (text.includes('private')) return 'private';
-        if (text.includes('protected')) return 'protected';
-        if (text.includes('internal')) return 'internal';
-      }
-    }
-    return 'public'; // Kotlin defaults to public
-  },
+  getVisibility: (node) => kotlinVisibility(node),
   isStatic: (_node) => {
     // Kotlin doesn't have static, uses companion objects
     return false;

src/resolution/name-matcher.ts

@@ -3384,6 +3384,38 @@ function isSfcPrivate(n: Node, context: ResolutionContext): boolean {
   return true;
 }
 
+/** Per-context memo: node id → "this member sits inside a `private` class/object". */
+const PRIVATE_OWNER_MEMO = new WeakMap<ResolutionContext, Map<string, boolean>>();
+
+/** Kinds that own members and carry a visibility of their own. */
+const OWNER_KINDS = new Set<string>(['class', 'interface', 'struct', 'enum', 'namespace']);
+
+/**
+ * Whether `candidate` is a member of a `private` type in its file — a Kotlin
+ * test's `private class Clock { fun now() = value }`: the method is public,
+ * the class is not, so nothing outside the file can name `now`. Found by
+ * line range among the file's own nodes, memoised per node.
+ */
+function isInsidePrivateType(candidate: Node, context: ResolutionContext): boolean {
+  let memo = PRIVATE_OWNER_MEMO.get(context);
+  if (!memo) {
+    memo = new Map();
+    PRIVATE_OWNER_MEMO.set(context, memo);
+  }
+  const hit = memo.get(candidate.id);
+  if (hit !== undefined) return hit;
+  const inside = context.getNodesInFile(candidate.filePath).some(
+    (n) =>
+      n.id !== candidate.id &&
+      OWNER_KINDS.has(n.kind) &&
+      n.visibility === 'private' &&
+      n.startLine <= candidate.startLine &&
+      n.endLine >= candidate.endLine
+  );
+  memo.set(candidate.id, inside);
+  return inside;
+}
+
 /**
  * Whether Go lets `ref`'s file name the Go declaration `candidate`: an
  * exported name from anywhere, an unexported one only inside its own package,
@@ -3525,7 +3557,12 @@ export function isVisibleAcrossFiles(candidate: Node, ref: UnresolvedRef, contex
   if (lang === 'dart') {
     return candidate.visibility !== 'private' || (ref.language === 'dart' && dartPrivateVisible(ref.filePath, candidate.filePath, context));
   }
-  if (PRIVATE_IS_FILE_LOCAL.has(lang)) return candidate.visibility !== 'private';
+  if (PRIVATE_IS_FILE_LOCAL.has(lang)) {
+    // Only Kotlin's private type keeps its members in its file: a Scala
+    // `private[pkg] class` (or one with a private constructor) is the package's,
+    // and a C# private nested class serves every file of its partial class.
+    return candidate.visibility !== 'private' && !(lang === 'kotlin' && isInsidePrivateType(candidate, context));
+  }
   // An R test file runs in an environment of its own (testthat): its top-level
   // `c <- ggplot(…)` is not what the package's 2,843 `c(…)` calls mean. The
   // `helper-*.R` / `setup-*.R` files are sourced for every test, so theirs are shared.
@@ -19425,6 +19462,7 @@ export function clearNameMatcherMemos(context: ResolutionContext): void {
   JAVA_STATIC_IMPORTS.delete(context);
   PY_IMPORTS.delete(context);
   PY_MODULE_LOCAL.delete(context);
+  PRIVATE_OWNER_MEMO.delete(context);
   SEALED_MODULES.delete(context);
   LOCAL_BINDING_MEMO.delete(context);
   LOCAL_BINDING_SITES.delete(context);