deferStmt

fn deferStmt(
    gz: *GenZir,
    scope: *Scope,
    node: Ast.Node.Index,
    block_arena: Allocator,
    scope_tag: Scope.Tag,
) InnerError!*Scope {
    var defer_gen = gz.makeSubBlock(scope);
    defer_gen.cur_defer_node = node.toOptional();
    defer_gen.any_defer_node = node.toOptional();
    defer defer_gen.unstack();

    const tree = gz.astgen.tree;
    const expr_node = tree.nodeData(node).node;
    _ = try unusedResultExpr(&defer_gen, &defer_gen.base, expr_node);
    try checkUsed(gz, scope, &defer_gen.base);
    _ = try defer_gen.addBreak(.break_inline, @fromBackingInt(@intCast(0)), .void_value);

    const body = defer_gen.instructionsSlice();
    const body_len = gz.astgen.countBodyLenAfterFixupsExtraRefs(body, &.{});

    const index: u32 = @intCast(gz.astgen.extra.items.len);
    try gz.astgen.extra.ensureUnusedCapacity(gz.astgen.gpa, body_len);
    gz.astgen.appendBodyWithFixupsExtraRefsArrayList(&gz.astgen.extra, body, &.{});

    const defer_scope = try block_arena.create(Scope.Defer);

    defer_scope.* = .{
        .base = .{ .tag = scope_tag },
        .parent = scope,
        .index = index,
        .len = body_len,
    };
    return &defer_scope.base;
}