015 nested inline effect arg shadow

// Pin: nested INLINED effect events that share an input arg name emit
// shadowing `const`s. `outer(n: 3)` inlines its body; inside its `! v` arm it
// calls `leaf(n: 3)` which ALSO inlines — and both lower their `n` arg to
// `const n = (3)` in NESTED scopes, so the inner one shadows the outer:
//
//     { const n = (3); ... { const n = (3); ... } }   // Zig: shadow error
//
// The fix is to give each inline frame's arg binding a scope-unique name (or
// reuse the outer when identical). Surfaced by the nested_3_levels benchmark.
//
// Expected: outer fires `v` 3×; each firing inlines leaf, which fires `v` 3×;
// each of those calls inc → counter = 3 × 3 = 9.
~import std/io

const std = @import("std");

var counter: u64 = 0;

~pub event leaf { n: u64 }
! v u64

~proc leaf|zig {
    for (0..n) |i| v(i);
}

~pub event outer { n: u64 }
! v u64

~proc outer|zig {
    for (0..n) |i| v(i);
}

~pub event inc {}

~proc inc|zig {
    counter +%= 1;
}

~pub event show {}

~proc show|zig {
    std.debug.print("{d}\n", .{counter});
}

~outer(n: 3)
! v _ |> leaf(n: 3)
    ! v _ |> inc()
~show()