Can't specify collation for virtual columns

You can specify the character set for a virtual column but not the collation. I.e. the following is not allowed:

CREATE TABLE t1(c1 CHAR(10), c2 CHAR(10) COLLATE utf8_bin AS(c1));

but the following is allowed:

CREATE TABLE t1(c1 CHAR(10), c2 CHAR(10) CHARACTER SET utf8 AS(c1));

The reason why one would want to do this would be to allowing several indexes on the same column using different collations. This is possible to achieve using a workaround, and once this is done index lookups and sorting works as expected. To create a table with UTF8 column and having both swedish and german collations:

CREATE TABLE t1(c1 CHAR(10) CHARACTER SET utf8 COLLATE utf8_swedish_ci,

  c2 CHAR(10) AS (c1),

  KEY(c1),

  KEY(c2)) CHARACTER SET utf8 COLLATE utf8_german2_ci;

Using this construct I can now select from the table and use an indexed sort using either german or swedish collations. But I can not explicitly set the collation of the virtual column here, I can only set the source column (c1) to a dofferent collation than the default for the table and let the table default affect the virtual column.