to enable both recompiling mysqli or odbc from sources in addition to drop-in replacement functionality.
The case in question is compiling mysqli from sources, that needs client_errors via ER() macro.
Previously, we exported it as mysql_client_errors (compatibly to Fedora's style symbol renaming, see MDEV-3842).
However, if MariaDB header files are used when compiling mysqli, client_errors needs to be exported with its original name.
Miscellaneous workarounds for drop-in compatibility problems with Linux distributions, arounf versioning of the
MySQL 5.5 client shared library. There seems to be 3 different ways major distributions handle versioning
1. Fedora (also Mageia, and likely other Redhat descendants) way
old, 5.1 API functions are given version libmysqlclient_16
new API functions (client plugins, mysql_stmt_next ) are given version libmysqlclient_18
some extra functions beyond API are exported.
some functions are renamed.
2.Debian Wheezy way
all functions are given libmysqlclient_18 version
3. Ubuntu way (or MySQL/MariaDB download packages)
no versioning
UIp to this fix, MariaDB distributions did not have any versioning in the libraries, this rendered client library incompatible to distributions
thus exchanging distribution's libmysqlclient.so.18.0.0 with MariaDB's did not work nicely (anywhere but on Ubuntu)
THE FIX
is to build libraries the same way as distributions do it
- when building RPMs, use same version script as Fedora does, Make sure to export extra-symbols, the same as Fedora exports.
- when building DEBs, use the same version script as Debian Wheezy
- do not use version scripts otherwise
Also, makes sure that extensions of MySQL APIs (asynchronous client functionality) is exported by the shared libraries.
