// `try` rejections (ERR step E1.4a):
//   - `try` is only valid inside a failable function,
//   - the operand must be failable (the sole failable-operand check —
//     the parser imposes none),
//   - propagating a `try` whose callee's error set is not a subset of the
//     caller's named set is rejected (widening at a function-propagation site).
// The positive case lives in `examples/221-try.sx`.

#import "modules/std.sx";

A :: error { Xa }
B :: error { Yb }

ga    :: () -> !A  { return; }
gb    :: () -> !B  { return; }
plain :: () -> s32 { return 0; }

// `try` in a non-failable function.
bad_ctx :: () -> s32 {
    try ga();                  // error: `try` outside a failable function
    return 0;
}

// `try` on a non-failable operand.
bad_operand :: () -> !A {
    try plain();               // error: operand has type s32 (not failable)
    return;
}

// Callee's set (B = {Yb}) is not a subset of the caller's set (A = {Xa}).
widen :: () -> !A {
    try gb();                  // error: Yb not in caller's error set A
    return;
}

main :: () -> s32 {
    a := bad_ctx();            // force bad_ctx to lower
    b := bad_operand();        // force bad_operand to lower
    c := widen();              // force widen to lower
    return 0;
}