identifier

fn identifier(zg: *ZonGen, node: Ast.Node.Index, dest_node: Zoir.Node.Index) !void {
    const tree = zg.tree;
    assert(tree.nodeTag(node) == .identifier);
    const main_token = tree.nodeMainToken(node);
    const ident = tree.tokenSlice(main_token);

    const tag: Zoir.Node.Repr.Tag = t: {
        if (mem.eql(u8, ident, "true")) break :t .true;
        if (mem.eql(u8, ident, "false")) break :t .false;
        if (mem.eql(u8, ident, "null")) break :t .null;
        if (mem.eql(u8, ident, "inf")) break :t .pos_inf;
        if (mem.eql(u8, ident, "nan")) break :t .nan;
        try zg.addErrorNodeNotes(node, "invalid expression", .{}, &.{
            try zg.errNoteNode(node, "ZON allows identifiers 'true', 'false', 'null', 'inf', and 'nan'", .{}),
            try zg.errNoteNode(node, "precede identifier with '.' for an enum literal", .{}),
        });
        return;
    };

    zg.setNode(dest_node, .{
        .tag = tag,
        .data = 0, // ignored
        .ast_node = node,
    });
}