[colbymchenry]

Summary

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. Nothing outside their file can name them, but cross-file calls of the same name landed on them: collections' filter { … } on a class's private IntentFilter filter, OkHttp enqueue(…) calls on a private inner class's enqueue, JavaScript, Go or Python callers on a Kotlin test fixture's private val.

Root cause

A Kotlin property was indexed without its visibility modifier, so the Kotlin file-local rule (#1745), which declines a private fun from another file, read every property as public. A member of a private class or object carries no private of its own, so the rule let it through as well.

From the contributor, and what we changed

From @danusha2345 (#1761), unchanged: both extractors (the wasm path and the native kernel) read a property's modifiers as they already did a function's; the parity fixture gains a private val and an internal var; isVisibleAcrossFiles declines a candidate inside a private type in its file (by line range, memoised per node); the two cross-file-visibility.test.ts cases.

Our changes:

• The private-owner rule is Kotlin's alone. The PR applied it to every language where private is file-local. A Scala private[pkg] class, or one with a private constructor, belongs to its package, and a C# private nested class serves every file of its partial class: on main of that day, http4s lost 742 edges with the rule (right ones among them, like stream.receiveHeaders() on the private[h2] class H2Stream), scalachess 91, serilog 10 (9 of them right typed edges). A Kotlin private constructor leaves its class public, which the rule never looked at.
• CHANGELOG: rewritten in the house format, after the other Kotlin call bullets.
• Rebased onto main 01e0ac3a, which has fix(kotlin): type receivers from declarations; parse fun interface #1933's Kotlin receiver typing (fix(kotlin): a call through a property or a receiver chain resolves on its declared type #2972); the patch applies unchanged.

Validation

Tests. cross-file-visibility.test.ts: the 2 Kotlin cases are red on main and green here; kernel-kotlin-parity.test.ts green with the rebuilt kernel.

Kernel parity (scripts/kernel-parity.mjs --lang kotlin), 0 files with diffs: okhttp 588/619 files byte-identical, mihon 891/940, nowinandroid 340/350, SystemUI's Kotlin files 188/198, the torture fixture 1/1; the rest are deferred to wasm on parse errors, the same files as with main's kernel.

A/B against main 01e0ac3a, fresh indexes with each arm's kernel, edges compared by site and target identity:

repo	edge sites added	removed	retargeted
square/okhttp c317930	0	274	0
mihonapp/mihon d001e6f	0	177	0
LineageOS SystemUI (lineage-18.1, sparse; Java + Kotlin)	0	94	0
android/nowinandroid 2982e63	identical
openjdk/jextract (Java), pallets/click, gin-gonic/gin (controls)	identical

Every removed edge, checked one by one against the new graph, is a call from another file onto a private Kotlin property (okhttp 54, mihon 154, SystemUI 5) or onto a member of a private Kotlin class or object (220, 23, 89). The largest groups: okhttp's private inner AndroidDns.AndroidQuery.enqueue (71) and RealWebSocketTest's private TestStreams.source (59); mihon's private val filter = IntentFilter() that collections' filter { … } reached (65) and MangaRestorer's private now (47); SystemUI's private PrivacyItemController.MyExecutor.execute (43) and ControlsBindingControllerImpl.CallbackRunnable.run (13).

Before #1933, against main 4eb8c2a5, the same change removed okhttp 307, mihon 237 and nowinandroid 7 (MutableStateFlow.update { … } reaching a private ScrollThumbElement.update). The difference is calls #1933 now handles itself: it leaves a call on a library type unlinked, or types it onto its declared class (mihon's register calls reach the Preference.register extension, okhttp's connectionCount() reaches ConnectionPool), so they no longer land on a private declaration. http4s, scalachess (Scala) and serilog (C#) were identical in that run, as the private-owner rule is Kotlin's alone.

Cost (mihon, median of 3 interleaved fresh indexes, on main 4eb8c2a5): process CPU 25.7 s on main vs 25.5 s, wall 8.2 s on both.

Suite: CODEGRAPH_KERNEL_EXPECT=1 npx vitest run --maxWorkers=4 --minWorkers=1 on 2aecd2ed (Windows 11, kernel built): 774 files passed, 6 skipped; 9,245 tests passed, 85 skipped, 0 failed.

Lands #1761 by @danusha2345.

🤖 Generated with Claude Code