Tk fails to build. Errors: libpng and libjpeg errors during testing. Missing library symbols in libpng and libjpeg.
Tk Makefile requires pkg-config, which is not present in Mac OS X 10.15.6 Catalina. The Makefile gets an error when it attempts to execute pkg-config which it interprets as the libpng.dylib not being present. The dependency of Tk on pkg-config should be made explicit, and if the build fails because pkg-config is absent, it should be reported to the installer. When pkg-config is absent, the Maekfile falls back to the native Mac OSX Frameworks libPNG.dylib, which is the cause of the missing library symbols.
Once pkg-config is installed (via homebrew), the installation fails because of missing symbols in libjpeg. Oddly, the Makefile does not use pkg-config to determine the libpng.dylib to use and even with pkg-config present, the Makefile falls back to the native Mac OSX Frameworks libJPEG.dylib, which is the cause of the missing library symbol errors.
I suggest 2 remedies:
1) Make the dependency on pkg-config explicit, and add a test in the build script to test for pkg-config and report an error if it is not found.
2) Use the same pkg-config method for finding the proper libjpeg.dylib as is used with libpng.dylib, rather than having 2 different methods for identifying which library to use.
Darwin 19.6.0
This is perl 5, version 30, subversion 2 (v5.30.2) built for darwin-2level
libpng and libjpeg installed via Homebrew
RT for rt.cpan.org