052 stale record field in interpolation

✓ Passing Passing: the compiler rejects this program as expected.

Code

// PIN: a discharged RECORD FIELD read through a `{{ }}` interpolation escapes
// the use-after-discharge wall.
//
// Both halves work on their own, which is what makes this the two-lowerings
// shape rather than a missing feature:
//
//   plain binding  + argument      -> caught (335_024, 335_025, 335_047)
//   plain binding  + interpolation -> caught
//   record field   + argument      -> caught ("binding 'r.k' was already
//                                     discharged" — the composite key IS the
//                                     name the checker reports)
//   record field   + interpolation -> THIS TEST
//
// phantom_semantic_checker.zig's interpolation scanner walks a slot for
// identifiers and skips any segment preceded by `.`, on the stated ground that
// "a trailing `.field` names a field, not a binding". True for an ordinary
// record — and the exact case that misses here, because an obligation carried
// on a record field is disposed under `r.k`, a name the scan never forms.
//
// Found while testing whether a borrow could be tied to its owner by minting
// two obligations and discharging them together (610_007's open question). The
// tie held; this is what leaked out from under it.

import app/holder
import std/io

app/holder:grab(name: "x"): r |> app/holder:drop(h: r.k) |> std/io:print.ln("{{ r.k:s }}")

input.k

Supporting Files

// An obligation that arrives as a RECORD FIELD, so the discharge is tracked
// under the composite key `r.k` rather than a plain binding name.
const std = @import("std");

var buf: [16]u8 = undefined;

~pub tor grab { name: string } -> { k: string<held!>, n: u32 }

~proc grab|zig {
    _ = name;
    @memcpy($mod.buf[0..3], "abc");
    return .{ .k = $mod.buf[0..3], .n = 7 };
}

~pub tor drop { h: string<!held> }

~proc drop|zig {
    _ = h;
}

holder.kz

Actual compiler output

error[KORU030]: Use-after-discharge: binding 'r.k' was already discharged and cannot be used
  --> tests/regression/300_ADVANCED_FEATURES/335_OBLIGATION_STRESS/335_052_stale_record_field_in_interpolation/input.k:27:0

❌ Compiler coordination error: Phantom semantic validation failed
   (set KORU_BACKEND_TRACE=1 for the backend return trace)

Must contain:

Use-after-discharge

Flows

flow ~grab click a branch to expand · @labels scroll to their anchor

grab (name: "x")

Test Configuration

MUST_ERROR

← 051 explicit then auto discharge 054 discharge a binding that never owed →