Regression in 10.11.19: valid MyISAM table with mixed virtual columns rejected with ERROR 1033

MariaDB 10.11.19 rejects a MyISAM table definition that works on 10.11.18. This affects both CREATE TABLE and opening existing table files created by 10.11.18.

Minimal reproduction

CREATE TABLE minimal_interleaved (

  a INT,

  z CHAR(0) GENERATED ALWAYS AS (NULL) VIRTUAL,

  b INT,

  v INT GENERATED ALWAYS AS (a) VIRTUAL

) ENGINE=MyISAM

  DEFAULT CHARSET=utf8mb3

  COLLATE=utf8mb3_unicode_ci;

Expected result

The table is created successfully, as on 10.11.18.

Actual result on 10.11.19

CREATE TABLE fails with:

ERROR 1033 (HY000): Incorrect information in file: './native19/minimal_interleaved.frm'

Subsequent queries return ERROR 1146 because the failed CREATE does not leave an accessible table.

Possible connection to MDEV-40571

MDEV-40571 introduced additional .frm field-layout validation in 10.11.19. The interaction between an interleaved zero-length virtual column and a later nonzero-length virtual column appears relevant.