037 default discharge must be void

✓ Passing This code compiles and runs correctly.

Code

// TEST: [!] annotation on multi-branch event is a compile error
//
// MUST_FAIL
//
// The [!] annotation marks an event as the default auto-discharge target.
// But events with multiple branches CANNOT be auto-discharged
// (because multiple branches require manual handling).
//
// Marking a multi-branch event with [!] is contradictory and should error.
//
// Expected: Compile error about [!] requiring single-outcome event

// Resource with obligation
pub const Handle = struct {
    id: i32,
};

// Event that creates obligation
~event open {}
| ok *Handle[open!]

~proc open {
    const h = std.heap.page_allocator.create(Handle) catch unreachable;
    h.* = .{ .id = 42 };
    return .{ .ok = h };
}

// ERROR: [!] on event with branches is invalid
// Branched events require manual handling, cannot be auto-discharged
~[!]event close { h: *Handle[!open] }
| closed {}
| error { msg: []const u8 }

~proc close {
    std.heap.page_allocator.destroy(h);
    return .{ .closed = .{} };
}

const std = @import("std");

input.kz

Error Verification

Actual Compiler Output

[PHASE 2.4] Calling run_pass for transforms\n[PHASE 2.5] Executing comptime_main() - running comptime flows
[PHASE 2.5] Comptime flows complete (38 items)
[PHASE 2.6] Rescanning transformed AST (38 items)
[PHASE 2.6] Rescan complete: 25 comptime events found
  [0] std.compiler:requires
  [1] std.compiler:flag.declare
  [2] std.compiler:command.declare
  [3] std.compiler:coordinate
  [4] std.compiler:context_create
  [5] std.testing:test
  [6] std.testing:validate_mocks
  [7] std.testing:test.with_harness
  [8] std.testing:test.harness
  [9] std.testing:assert
  [10] std.testing:test.property.equivalent
  [11] std.deps:deps
  [12] std.deps:requires.system
  [13] std.deps:requires.zig
  [14] std.control:if
  [15] std.control:for
  [16] std.control:capture
  [17] std.control:const
  [18] std.build:requires
  [19] std.build:variants
  [20] std.build:config
  [21] std.build:command.sh
  [22] std.build:command.zig
  [23] std.build:step
  [24] std.template:define
error[KORU083]: [!] annotation requires single-outcome event - events with multiple branches require manual handling
  --> auto_discharge:34:0

error[KORU083]: [!] annotation requires single-outcome event - events with multiple branches require manual handling
  --> auto_discharge:34:0

❌ Compiler coordination error: Auto-discharge failed (multiple disposal options or no disposal event)
error: CompilerCoordinationFailed
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/330_PHANTOM_TYPES/330_037_default_discharge_must_be_void/backend.zig:9353:17: 0x1007ae433 in emit (backend)
                return error.CompilerCoordinationFailed;
                ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/330_PHANTOM_TYPES/330_037_default_discharge_must_be_void/backend.zig:9437:28: 0x1007af1bf in main (backend)
    const generated_code = try RuntimeEmitter.emit(compile_allocator, final_ast);
                           ^

Test Configuration

MUST_FAIL

Expected Behavior:

MUST_FAIL
# Should error because [!] is applied to an event with multiple branches
CONTAINS KORU083
CONTAINS single-outcome

← 036 autodischarge no void candidate 040 undisposed nested obligation →