[MacPorts] #54197: libpurple / pidgin @2.12.0 fails to build if port:tcl and port:tk are present

[MacPorts]

#54197: libpurple / pidgin @2.12.0 fails to build if port:tcl and port:tk are
present
---------------------------+-------------------------------
 Reporter:  detlevd        |      Owner:
     Type:  defect         |     Status:  new
 Priority:  Normal         |  Milestone:
Component:  ports          |    Version:  2.4.1
 Keywords:  version clash  |       Port:  libpurple, pidgin
---------------------------+-------------------------------
 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.

--
Ticket URL: <https://trac.macports.org/ticket/54197>
MacPorts <https://www.macports.org/>
Ports system for macOS