Symbol versioning in Linux distributions

[Miroslav Lichvar]

Hi,

in ncurses-6.0 was added support for versioning of symbols in the
ncurses libraries, which by default is disabled. It seems some
distributions are already using it. As the maintainer of the Fedora
package I was wondering if there are any upstream recommendations for
distributions whether to build with this feature enabled or disabled.

The INSTALL text describes the map files as samples. Does that mean
incompatible changes in the naming are expected to happen?

It's not clear to me what exactly is the intention of this feature.
To allow the library to have the same symbol in multiple versions to
not break the ABI for old binaries like glibc does for instance? Or
just to make it easier to see what ncurses version (patch?) a binary
needs to run?

Now that some distributions use it and some don't I think there is a
problem that binaries built with versioned symbols won't load on
distributions that don't have it enabled yet. I'm not sure if anyone
needs to do that these days. It also means it's difficult to disable
it once it's enabled, so I'd like to know what I'm getting into :).

-- 
Miroslav Lichvar