libpurple / pidgin @2.12.0 fails to build if port:tcl and port:tk are present

[detlevd (Detlev Droege)]

OSX Sierra 10.12.5, XCode 8.3.2: When trying to install pidgin, which in turn installs libpurple, building fails with the message

:info:build In file included from tcl.c:28:
:info:build /opt/local/include/tk.h:21:3: error: Tk 8.6 must be compiled with tcl.h from Tcl 8.6 or better

in main.log (full file attached).

Apparently, this occurs because I have ports tcl and tk installed

The following ports are currently installed:
  tcl @8.6.6_1+corefoundation+threads (active) platform='darwin 16' archs='x86_64' date='2017-01-30T14:06:56+0100'
  tk @8.6.6_0+quartz (active) platform='darwin 16' archs='x86_64' date='2017-01-09T10:03:23+0100'

and the search path order for include files is handled inconsistently. Some component reads tk.h from /opt/local/include/tk.h but its include of tcl.h is fullfilled from /System/Library/Frameworks/Tcl.framework/Versions/8.5/Headers, which is v8.5 and not v8.6.

Workaround:

If you have ports tcl and tk installed (and only then), you can add

                    --with-tkconfig=${prefix}/lib \
                    --with-tclconfig=${prefix}/lib \

to the configure.args in pidgin/Portfile to straighten the search paths.

The other way around, stating /usr/lib for both config search paths, to always use the OSX Tcl/Tk 8.5 framework, unfortunately does not work.