parse errors in loadable UCA / LDML collations are silently ignored

[12 Jun 21:22] Hartmut Holzgraefe

Description:
When defining a UCA collation using LDML syntax in share/charsets/Index.xml any syntax errors in the collation definitions lead to the collation not being available after mysqld restart without providing any startup error message about the parse failure whatsoever.

How to repeat:

• Add the utf8_phone_ci example from
  http://dev.mysql.com/doc/refman/5.5/en/ldml-collation-example.html

• restart mysqld and verify that columns using utf8_phone_ci can be used

• now add a parse error, e.g. by simply removing the 'u' after the backslash in one of the unicode code point definitions, like replacing

<reset>\u0000</reset>

with

<reset>\0000</reset>

• restart the server once more

• verify that utf8_phone_ci can't be used anymore

• check the mysqld error log for any collation related error message

=> there is none

Suggested fix:
Report errors found while parsing the loadable collations during startup to the mysqld error log