Parsing binary type with macros in size fails

[kvakvs]

The following should parse into a binary type.

-define(TXS_HASH_BYTES, 32).
-type(txs_hash() :: <<_:(?TXS_HASH_BYTES*8)>>).

More examples:

-type fr_bin() :: <<_:?FR_SIZE>>.
-type fp_bin() :: <<_:?FP_SIZE>>.

Current behaviour: Bad syntax.
Blocker: Macros expand into numbers, but the plugin does not preprocess macros.

Expected behaviour: Successfully parsed and syntax coloring working (at least neutral solid colour).
Possible temporary workaround: Assume that macro resolves to something that's allowed in this position. An integer?