ghostscript @9.26 build failure: Library not loaded: /opt/local/lib/libpng16.16.dylib

[jhand0867 (JoeFV67)]

macOS 10.14 (darwin/18.6.0) arch i386
MacPorts 2.5.4
Xcode 10.2.1
SDK 10.14
MACOSX_DEPLOYMENT_TARGET: 10.14

--->  Building ghostscript
Error: Failed to build ghostscript: command execution failed
Error: See /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_print_ghostscript/ghostscript/main.log for details.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port inkscape failed

[jhand0867 (JoeFV67)]

log from /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_print_ghostscript/ghostscript/main.log

[jmroot (Joshua Root)]

Error in the log is:

dyld: Library not loaded: /opt/local/lib/libpng16.16.dylib
   Referenced from: /opt/local/lib/libfreetype.6.dylib
   Reason: Incompatible library version: libfreetype.6.dylib requires version 53.0.0 or later, but libpng16.16.dylib provides version 44.0.0

Please show the output of these commands:

port installed freetype libpng

file /opt/local/lib/libfreetype.6.dylib /opt/local/lib/libpng16.16.dylib

otool -L /opt/local/lib/libfreetype.6.dylib /opt/local/lib/libpng16.16.dylib

[ryandesign (Ryan Carsten Schmidt)]

Replying to jmroot:

dyld: Library not loaded: /opt/local/lib/libpng16.16.dylib
   Referenced from: /opt/local/lib/libfreetype.6.dylib
   Reason: Incompatible library version: libfreetype.6.dylib requires version 53.0.0 or later, but libpng16.16.dylib provides version 44.0.0

This should not be happening. The libpng port is currently at version @1.6.37 and it provides libpng16.16.dylib version 54.0.0. libpng16.16.dylib version 44.0.0 was provided by libpng @1.6.27, which dates back to December 2016. Somehow you have managed to downgrade your libpng port to this version. Please upgrade it to the latest version.

If port installed libpng shows that MacPorts thinks a newer version than 1.6.27 is installed, then perhaps what happened is that you used a third party installer that had itself been built with MacPorts, and it overwrote some of your installed ports with whatever older version the installer was built with. If this is what happened, it can be nearly impossible to identify and manually correct everything that this broke, and the easiest solution is to uninstall all ports and then reinstall the ports you want. If you can remember what installer you ran that did this, you should also report the problem to whoever distributed that installer and advise them to fix their installer so that it does not install files into the default MacPorts prefix.

The log also shows a subsequent build attempt which resulted in this error:

:info:build dyld: Library not loaded: /opt/local/lib/libidn.11.dylib
:info:build   Referenced from: /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_print_ghostscript/ghostscript/work/ghostscript-9.26/./soobj/aux/genarch
:info:build   Reason: image not found
:info:build dyld: Library not loaded: /opt/local/lib/libidn.11.dylib
:info:build   Referenced from: /opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_tarballs_ports_print_ghostscript/ghostscript/work/ghostscript-9.26/./soobj/aux/echogs
:info:build   Reason: image not found

When you first tried to build ghostscript, it configured itself to use libidn.11.dylib. After the build failure, you must've upgraded the libidn port to a new version that provides libidn.12.dylib. You then tried to rebuild ghostscript without cleaning before trying again, resulting in this error. Clean ghostscript before trying again to avoid this error.

[ryandesign (Ryan Carsten Schmidt)]

I'm going to call this invalid since I believe it was caused by a non-MacPorts installer modifying MacPorts-installed software.