suspendExpr

fn suspendExpr(
    gz: *GenZir,
    scope: *Scope,
    node: Ast.Node.Index,
) InnerError!Zir.Inst.Ref {
    const astgen = gz.astgen;
    const gpa = astgen.gpa;
    const tree = astgen.tree;
    const body_node = tree.nodeData(node).node;

    if (gz.nosuspend_node.unwrap()) |nosuspend_node| {
        return astgen.failNodeNotes(node, "suspend inside nosuspend block", .{}, &[_]u32{
            try astgen.errNoteNode(nosuspend_node, "nosuspend block here", .{}),
        });
    }
    if (gz.suspend_node.unwrap()) |suspend_node| {
        return astgen.failNodeNotes(node, "cannot suspend inside suspend block", .{}, &[_]u32{
            try astgen.errNoteNode(suspend_node, "other suspend block here", .{}),
        });
    }

    const suspend_inst = try gz.makeBlockInst(.suspend_block, node);
    try gz.instructions.append(gpa, suspend_inst);

    var suspend_scope = gz.makeSubBlock(scope);
    suspend_scope.suspend_node = node.toOptional();
    defer suspend_scope.unstack();

    const body_result = try fullBodyExpr(&suspend_scope, &suspend_scope.base, .{ .rl = .none }, body_node, .normal);
    if (!gz.refIsNoReturn(body_result)) {
        _ = try suspend_scope.addBreak(.break_inline, suspend_inst, .void_value);
    }
    try suspend_scope.setBlockBody(suspend_inst);

    return suspend_inst.toRef();
}