137 comptime walk source arg refuses

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

Code

// Pins the named wall a [comptime] subflow impl hits when its body invokes
// a transform: transforms rewrite call-site flows at elaboration, so a raw
// `capture` inside a walked impl body is a Source capture arriving at a
// call evaluator. Before the wall, evalArgs fed the captured text (`v:
// 40[i64]`) to the expression parser — a misleading TrailingGarbage error —
// and earlier still the same program panicked on the emitted-`arg.value`
// splice. The refusal names the boundary: Source params belong to
// transforms, which run at elaboration, not to walkable calls.

import std/io

[comptime] pub tor get-input {} -> i64

[comptime] get-input = capture { v: 40[i64] }
! as a |> captured { v: a.v + 1 }
| captured c => result c.v

[comptime] get-input(): s |> std/io:print.ln("{{ s:d }}")

input.k

Actual compiler output

comptime fold failed: comptime walk: argument `source` is a Source capture — Source params belong to transforms, which run at elaboration, not to walkable calls
thread 440235992 panic: comptime evaluation failed — see the diagnostic above
/Users/larsde/src/koru/src/comptime_eval.zig:180:9: 0x1026b2a23 in fail__anon_117702 (backend)
        return err;
        ^
/Users/larsde/src/koru/src/comptime_eval.zig:424:17: 0x102604d8f in evalArgs (backend)
                return self.fail(error.UnsupportedConstruct, "comptime walk: argument `{s}` is a Source capture — Source params belong to transforms, which run at elaboration, not to walkable calls", .{arg.name});
                ^
/Users/larsde/src/koru/src/comptime_eval.zig:490:43: 0x1026b2c9f in walkLabeledBody (backend)
        var head_args: []const ArgValue = try self.evalArgs(env, inv.args);
                                          ^
/Users/larsde/src/koru/src/comptime_eval.zig:464:9: 0x10260507b in walkFlow (backend)
        return self.walkLabeledBody(items, &flow.body, flow.pre_label, &env);
        ^
/Users/larsde/src/koru/src/comptime_eval.zig:793:24: 0x1024b6ccf in walkFlowResidue (backend)
        const result = try self.evaluator.walkFlow(program.items, sub, args);
                       ^
/Users/larsde/src/koru/src/comptime_eval.zig:749:48: 0x10225766b in fold (backend)
                                .walk => |sub| try self.walkFlowResidue(program, cur, sub),
                                               ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/310_COMPTIME/310_137_comptime_walk_source_arg_refuses/backend_output_emitted.zig:1201:25: 0x10223070b in handler (backend)
                        @panic("comptime evaluation failed — see the diagnostic above");
                        ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/310_COMPTIME/310_137_comptime_walk_source_arg_refuses/backend_output_emitted.zig:1233:85: 0x10222c963 in handler (backend)
                const __thread5 = koru_std.koru_compiler.fold_comptime_event.handler(.{ .ctx = __thread4 });
                                                                                    ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/310_COMPTIME/310_137_comptime_walk_source_arg_refuses/backend_output_emitted.zig:1025:74: 0x10222bf33 in handler (backend)
                const c1 = koru_std.koru_compiler.elaborate_event.handler(.{ .ctx = c0 });
                                                                         ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/310_COMPTIME/310_137_comptime_walk_source_arg_refuses/backend_output_emitted.zig:11007:67: 0x10222bd7f in koru_coordinate (backend)
    const result = koru_std.koru_compiler.coordinate_event.handler(.{
                                                                  ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/310_COMPTIME/310_137_comptime_walk_source_arg_refuses/backend.zig:93:39: 0x1021a93fb in emit (backend)
        const result = koru_coordinate(source_ast, &allocator);
                                      ^
/Users/larsde/src/koru/tests/regression/300_ADVANCED_FEATURES/310_COMPTIME/310_137_comptime_walk_source_arg_refuses/backend.zig:324:51: 0x1021aaef7 in main (backend)
    const generated_code = try RuntimeEmitter.emit(compile_allocator, final_ast);
                                                  ^
/opt/homebrew/Cellar/zig/0.15.2_1/lib/zig/std/start.zig:627:37: 0x1021b6207 in main (backend)
            const result = root.main() catch |err| {
                                    ^
???:?:?: 0x1816a3dff in ??? (???)
???:?:?: 0x0 in ??? (???)
/Users/larsde/src/koru/scripts/regression_lib.sh: line 494:  6170 Abort trap: 6           ./backend output

Error output must contain

is a Source capture — Source params belong to transforms, which run at elaboration, not to walkable calls

Flows

subflow ~get-input click a branch to expand · @labels scroll to their anchor

capture (source: v: 40[i64])

flow ~get-input click a branch to expand · @labels scroll to their anchor

get-input

Test Configuration

MUST_ERROR

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