Yes Fred, renabor, perhaps my wording was unclear.
Fred As you note, the only time libfontconfig is used is in fcl-pdf. That is where I use it. Obscure but it is part of FPC.
When loading the library, fcl-pdf uses the "linker name", it should use the "so name". The linker name is to be used when linking, not at run time. The linker name, in most Linuxes (except Arch etc), is not available unless the -dev package is installed. But the "so name" is almost certainly pre-installed.
None developers should not be expected to have have -dev packages installed.
Yes Fred, as you mention, all it needs is to change the name in FPC source. I have changed it in my FPC, it works as expected and is well tested over many months. But in the official release (and main and fixes) of FPC, its not changed. And it is wrong.
renabor yes installing the -dev package hides the problem, but, as I noted, end users should no be required to use a -dev package. Further, relying on a -dev package at run time risks complications when new versions of the library are released. We make a distinction between "linker name" and "so name" for that reason.
I recently updated the version of my app in Debian, I have had to include the -dev version of both ssl and libfontconfig as dependencies because Debian only every uses the official release of FPC. And both are broken in FPC322. That is NOT a fix, its a "work-around".
The real risk, as I noted, is a developer (who is expected to have the -dev packages) builds and tests an app on his/her own machine and it all works as expected. Then send it to an end user who, quite probably has no reason to even know -dev packages even exist.
Davo