✓
Passing This code compiles and runs correctly.
Code
// FRONTIER (pinned RED): the effect-branch inliner reuses the callee event's
// OWN declared parameter name verbatim as the inlined body's local `const`
// binding at the call site, with no gensym / alpha-renaming. If the caller
// already holds a local of that same name earlier in the same flow, Zig's
// no-shadow rule turns two individually-correct pieces of code into a hard
// backend build error.
//
// Related to 800_002 (a switch-capture vs. handler fn-param shadow) but
// DISTINCT: there the collision is a branch capture *inside* the handler; here
// it is the inlined *call-site* const vs. a *caller-scope* local. A fix for one
// need not fix the other — both should go green once the inliner alpha-renames
// the names it introduces.
//
// Surfaced 2026-07-10 by a LIFT-challenge contestant building @korulang/yyjson:
// `array.each`'s `v: []const i32` parameter collided with a caller binding also
// named `v` from an earlier `root(doc): v`. Minimal, yyjson-free repro below.
//
// `get-count` returns i32 directly (`-> i32`), destructured into a binding
// named `v` — ordinary caller code. `each-i32` is an effect-branch event
// (`! item`) whose own parameter is ALSO named `v`, coincidentally. Calling it
// downstream of the `v` binding should be fine (unrelated variables in
// unrelated code) — instead the inliner's substitution for `each-i32`'s `v`
// collides with the caller's `v`.
//
// EXPECTED (if the hygiene gap is fixed): compiles and runs, printing
// count: 3
// saw 10
// saw 20
// saw 30
// ACTUAL: output_emitted.zig: error: local constant 'v' shadows local constant
// from outer scope — see expected_error.txt.
~import std/io
~pub tor get-count { n: i32 } -> i32
~proc get-count|zig {
return n;
}
~pub tor each-i32 { v: []const i32 }
! item i32
~proc each-i32|zig {
for (v) |it| item(it);
}
~get-count(n: 3): v |> std/io:print.ln("count: {{ v:d }}") |> each-i32(v: &[_]i32{ 10, 20, 30 })
! item x |> std/io:print.ln("saw {{ x:d }}")
Supporting Files
~proc get-count|cs {
return n;
}
~proc each-i32|cs {
foreach (var it in v) item(it);
}Actual
count: 3
saw 10
saw 20
saw 30
Expected output
✓ Zig✓ C#count: 3
saw 10
saw 20
saw 30
Emitted Zig source
// Access compiler flags via the per-user compiler_env module
const CompilerEnv = @import("compiler_env").CompilerEnv;
pub const panic = if (@import("builtin").mode == .Debug)
@import("std").debug.FullPanic(@import("std").debug.defaultPanic)
else
@import("std").debug.simple_panic;
const __koru_bare = struct {
extern fn posix_memalign(memptr: *?*anyopaque, alignment: usize, size: usize) c_int;
extern fn free(ptr: ?*anyopaque) void;
fn bareAlloc(_: *anyopaque, len: usize, alignment: @import("std").mem.Alignment, _: usize) ?[*]u8 {
var p: ?*anyopaque = null;
const a = @max(alignment.toByteUnits(), @sizeOf(usize));
if (posix_memalign(&p, a, len) != 0) return null;
return @ptrCast(p);
}
fn bareResize(_: *anyopaque, _: []u8, _: @import("std").mem.Alignment, _: usize, _: usize) bool { return false; }
fn bareRemap(_: *anyopaque, _: []u8, _: @import("std").mem.Alignment, _: usize, _: usize) ?[*]u8 { return null; }
fn bareFree(_: *anyopaque, memory: []u8, _: @import("std").mem.Alignment, _: usize) void { free(@ptrCast(memory.ptr)); }
const vtable = @import("std").mem.Allocator.VTable{ .alloc = bareAlloc, .resize = bareResize, .remap = bareRemap, .free = bareFree };
const allocator = @import("std").mem.Allocator{ .ptr = undefined, .vtable = &vtable };
};
const __koru_backing = if (@import("builtin").link_libc) @import("std").heap.c_allocator else if (@import("builtin").os.tag == .freestanding) __koru_bare.allocator else @import("std").heap.page_allocator;
var __koru_leak_count: @import("std").atomic.Value(usize) = .init(0);
fn __koru_alloc(ctx: *anyopaque, len: usize, alignment: @import("std").mem.Alignment, ret_addr: usize) ?[*]u8 {
_ = ctx;
const r = __koru_backing.rawAlloc(len, alignment, ret_addr);
if (comptime @import("builtin").mode == .Debug) {
if (r != null) _ = __koru_leak_count.fetchAdd(1, .monotonic);
}
return r;
}
fn __koru_resize(ctx: *anyopaque, memory: []u8, alignment: @import("std").mem.Alignment, new_len: usize, ret_addr: usize) bool {
_ = ctx;
return __koru_backing.rawResize(memory, alignment, new_len, ret_addr);
}
fn __koru_remap(ctx: *anyopaque, memory: []u8, alignment: @import("std").mem.Alignment, new_len: usize, ret_addr: usize) ?[*]u8 {
_ = ctx;
return __koru_backing.rawRemap(memory, alignment, new_len, ret_addr);
}
fn __koru_free(ctx: *anyopaque, memory: []u8, alignment: @import("std").mem.Alignment, ret_addr: usize) void {
_ = ctx;
__koru_backing.rawFree(memory, alignment, ret_addr);
if (comptime @import("builtin").mode == .Debug) {
_ = __koru_leak_count.fetchSub(1, .monotonic);
}
}
const __koru_vtable = @import("std").mem.Allocator.VTable{ .alloc = __koru_alloc, .resize = __koru_resize, .remap = __koru_remap, .free = __koru_free };
pub fn koru_allocator() @import("std").mem.Allocator {
return .{ .ptr = undefined, .vtable = &__koru_vtable };
}
pub inline fn __koru_intcast(comptime T: type, x: anytype) T {
if (comptime (@import("builtin").mode == .Debug or @import("builtin").mode == .ReleaseSafe))
return @as(T, @intCast(x));
const dst = @typeInfo(T);
const src = @typeInfo(@TypeOf(x));
if (comptime (dst == .int and src == .int and dst.int.bits == src.int.bits and dst.int.signedness != src.int.signedness))
return @as(T, @bitCast(x));
return @as(T, @intCast(x));
}
pub fn koru_leak_check() void {
if (comptime @import("builtin").mode != .Debug) return;
if (__koru_leak_count.load(.acquire) == 0) return;
if (comptime @import("builtin").target.os.tag == .freestanding) {
if (comptime @import("builtin").cpu.arch == .wasm32 or @import("builtin").cpu.arch == .wasm64) {
@panic("KORU LEAK CHECK FAILED: the produced program leaked");
} else {
const __klc = struct { extern var stdout: ?*anyopaque; extern fn fputs(__s: [*:0]const u8, __st: ?*anyopaque) c_int; };
var __lb: [128]u8 = undefined;
const __lm = "KORU LEAK CHECK FAILED: allocations still outstanding at end of run: ";
@memcpy(__lb[0..__lm.len], __lm);
var __ln: usize = __lm.len;
var __lv = __koru_leak_count.load(.acquire);
var __ld: [20]u8 = undefined;
var __lk: usize = 0;
while (__lv > 0) : (__lk += 1) { __ld[__lk] = @intCast('0' + __lv % 10); __lv /= 10; }
for (0..__lk) |__li| { __lb[__ln] = __ld[__lk - 1 - __li]; __ln += 1; }
__lb[__ln] = '\n'; __ln += 1; __lb[__ln] = 0;
_ = __klc.fputs(@as([*:0]const u8, @ptrCast(&__lb)), __klc.stdout);
@trap();
}
} else {
@import("std").debug.print("KORU LEAK CHECK FAILED: the produced program leaked (trace above)\n", .{});
@import("std").process.exit(1);
}
}
pub const main_module = struct {
pub const get_count_event = struct {
pub const Input = struct {
n: i32,
};
pub const Output = i32;
pub inline fn handler(__koru_event_input: @This().Input) @This().Output {
return __koru_handler_impl(__koru_event_input.n);
}
fn __koru_handler_impl(__koru_p_0: i32) @This().Output {
const __koru_event_input: @This().Input = .{ .n = __koru_p_0 };
// >>> PROC: get_count [tests/regression/400_RUNTIME_FEATURES/400_151_effect_inliner_param_name_no_hygiene/input.kz:37]
const n = __koru_event_input.n;
_ = &n;
_ = &__koru_event_input;
return n;
}
};
pub const each_i32_event = struct {
pub const Input = struct {
v: []const i32,
};
pub const Output = void;
pub fn handler(__koru_event_input: @This().Input, comptime __H: type) @This().Output {
const item = __H.item;
_ = &item;
// >>> PROC: each_i32 [tests/regression/400_RUNTIME_FEATURES/400_151_effect_inliner_param_name_no_hygiene/input.kz:44]
const v = __koru_event_input.v;
_ = &v;
_ = &__koru_event_input;
for (v) |it| item(it);
}
};
// >>> FLOW: tests/regression/400_RUNTIME_FEATURES/400_151_effect_inliner_param_name_no_hygiene/input.kz:48 ~input:get_count()
pub fn flow0() void {
const v = main_module.get_count_event.handler(.{ .n = 3 });
(struct { fn __kout(__fd: i32, __b: []const u8) void { if (@import("builtin").os.tag == .freestanding) { const __kc = struct { extern var stdout: ?*anyopaque; extern var stderr: ?*anyopaque; extern fn fputs(__s: [*:0]const u8, __st: ?*anyopaque) c_int; }; var __kt: [4096]u8 = undefined; for (0..(__b.len + __kt.len - 2) / (__kt.len - 1)) |__ki| { const __kn = @min(__kt.len - 1, __b.len - __ki * (__kt.len - 1)); @memcpy(__kt[0..__kn], __b[__ki * (__kt.len - 1)..][0..__kn]); __kt[__kn] = 0; @import("std").mem.doNotOptimizeAway(__kc.fputs(@as([*:0]const u8, @ptrCast(&__kt)), if (__fd == 2) __kc.stderr else __kc.stdout)); } } else { @import("std").mem.doNotOptimizeAway(@import("std").posix.write(__fd, __b) catch @as(usize, 0)); } } fn __kw(comptime __f: []const u8, __a: anytype) void { var __kb: [65536]u8 = undefined; const __ks = @import("std").fmt.bufPrint(&__kb, __f, __a) catch __kb[0..0]; __kout(1, __ks); } }).__kw("count: {d}\n", .{v});
{
const __koru_arg_v_0 = (&[_]i32{ 10, 20, 30 }); _ = &__koru_arg_v_0;
for (__koru_arg_v_0) |it| { const x = it; _ = &x; (struct { fn __kout(__fd: i32, __b: []const u8) void { if (@import("builtin").os.tag == .freestanding) { const __kc = struct { extern var stdout: ?*anyopaque; extern var stderr: ?*anyopaque; extern fn fputs(__s: [*:0]const u8, __st: ?*anyopaque) c_int; }; var __kt: [4096]u8 = undefined; for (0..(__b.len + __kt.len - 2) / (__kt.len - 1)) |__ki_0| { const __kn = @min(__kt.len - 1, __b.len - __ki_0 * (__kt.len - 1)); @memcpy(__kt[0..__kn], __b[__ki_0 * (__kt.len - 1)..][0..__kn]); __kt[__kn] = 0; @import("std").mem.doNotOptimizeAway(__kc.fputs(@as([*:0]const u8, @ptrCast(&__kt)), if (__fd == 2) __kc.stderr else __kc.stdout)); } } else { @import("std").mem.doNotOptimizeAway(@import("std").posix.write(__fd, __b) catch @as(usize, 0)); } } fn __kw(comptime __f: []const u8, __a: anytype) void { var __kb: [65536]u8 = undefined; const __ks = @import("std").fmt.bufPrint(&__kb, __f, __a) catch __kb[0..0]; __kout(1, __ks); } }).__kw("saw {d}\n", .{x});
}
}
}
pub fn koru_start_flow() void {
const result_0 = koru_koru.start_event.handler(.{ });
const result_0_done = result_0.done;
_ = &result_0_done;
}
pub fn koru_end_flow() void {
const result_0 = koru_koru.end_event.handler(.{ });
const result_0_done = result_0.done;
_ = &result_0_done;
}
};
pub const koru_koru = struct {
pub const start_event = struct {
pub const Input = struct {
};
pub const Output = union(enum(u8)) {
done: struct {
},
};
pub fn handler(__koru_event_input: @This().Input) @This().Output {
_ = &__koru_event_input;
return .{ .done = .{} };
}
};
pub const end_event = struct {
pub const Input = struct {
};
pub const Output = union(enum(u8)) {
done: struct {
},
};
pub fn handler(__koru_event_input: @This().Input) @This().Output {
_ = &__koru_event_input;
return .{ .done = .{} };
}
};
};
pub fn main() void {
main_module.koru_start_flow();
main_module.flow0();
main_module.koru_end_flow();
if (comptime @import("builtin").mode == .Debug) koru_leak_check();
}
test {
@import("std").testing.refAllDeclsRecursive(@This());
}
Emitted C# source
static class main_module {
public static void __koru_stdout_write(dynamic s) => global::System.Console.Out.Write(s);
public static void __koru_stderr_write(dynamic s) => global::System.Console.Error.Write(s);
// The mutable handle carrier — `*String`-style resources are
// `new __KoruBox { data = … }` because C# anonymous types are
// read-only: `s.data = …` (std/string append/clear, handle
// mutation generally) needs a settable member.
public class __KoruBox { public dynamic data; }
// Textification for `{{ … }}` operands: C# bool ToStrings as
// `True` where Koru prints `true`, and the operand's static type
// is unknown at this boundary — a `(x) is bool` inline test would
// be a compile error on statically-typed operands instead. Generic
// on purpose: `dynamic` boxed every value-type operand — measured
// ~1s/10M elements on 012_threat_scanner — while T specializes to
// the operand's own ToString() with no box.
public static string __koru_str<T>(T v) => v is bool b ? (b ? "true" : "false") : v?.ToString();
public static class get_count_event {
public struct Input {
public int n;
}
public static int handler(Input __koru_input) {
var n = __koru_input.n;
return n;
return default;
}
}
public static class each_i32_event {
public struct Input {
public dynamic v;
}
public interface IOps {
void item(int __koru_arg);
}
public static dynamic handler<H>(Input __koru_input, H ops) where H : struct, IOps {
void item(int __koru_arg) => ops.item(__koru_arg);
var v = __koru_input.v;
foreach (var it in v) item(it);
return default;
}
}
public static class koru_start_event {
public struct Input {
}
public struct Output {
public string tag;
public dynamic done;
}
public static Output handler(Input __koru_input) => new Output { tag = "done" };
}
public static class koru_end_event {
public struct Input {
}
public struct Output {
public string tag;
public dynamic done;
}
public static Output handler(Input __koru_input) => new Output { tag = "done" };
}
public static void flow0() {
var v = main_module.get_count_event.handler(new get_count_event.Input { n = (int)(3)});
__koru_stdout_write("count: " + __koru_str(v) + "\n");
var __koru_handlers_0 = new __koru_handlers_0 { };
main_module.each_i32_event.handler(new each_i32_event.Input { v = new int[] { 10, 20, 30 }}, __koru_handlers_0);
}
public static void flow1() {
main_module.koru_start_event.handler(new koru_start_event.Input { });
}
public static void flow2() {
main_module.koru_end_event.handler(new koru_end_event.Input { });
}
struct __koru_handlers_0 : each_i32_event.IOps {
public void item(int __koru_arm_1) {
var x = __koru_arm_1;
__koru_stdout_write("saw " + __koru_str(x) + "\n");
}
}
}
static class Program {
static void Main() {
main_module.flow1();
main_module.flow0();
main_module.flow2();
}
}
Flows
flow ~get-count click a branch to expand · @labels scroll to their anchor
get-count (n: 3)
Test Configuration
MUST_RUN LANGUAGES: cs