[MacPorts] #58574: poppler upgrade fails if older poppler is installed

[MacPorts]

#58574: poppler upgrade fails if older poppler is installed
----------------------+----------------------
  Reporter:  RobK88   |      Owner:  dbevans
      Type:  defect   |     Status:  reopened
  Priority:  Normal   |  Milestone:
 Component:  ports    |    Version:  2.5.4
Resolution:           |   Keywords:
      Port:  poppler  |
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Comment (by michaelld):

 Replying to [comment:77 kencu]:
 > Replying to [comment:75 michaelld]:
 >
 > > > ... and have the code stop adding {{{-L/opt/local/lib}}} to that
 path, which seems both unnecessary and troublesome.
 > >
 > > This is actually OK, it turns out.
 >
 > Marcus found out that setting this while using {{{DYLD_LIBRARY_PATH}}}
 overrides system frameworks by making them use newer macports libraries
 like libjpeg, and so all the links fail. That's why he suggested using
 FALLBACK, which has it's own problems.

 Correct all around! So what I do is use `DYLD_LIBRARY_PATH` for the in-
 build paths and `DYLD_FALLBACK_LIBRARY_PATH` (and `LIBRARY_PATH` itself,
 which honestly is probably more important) for non-in-build-paths -- for
 example MP paths. I have the PKGCONFIG command return 2 variables instead
 of 1: the non"-L" entries and the "-L" entries. These are then handled
 separately, which means we've removed all of the system "-L" entries from
 the link command and instead rely on `DYLD_FALLBACK_LIBRARY_PATH` and
 `LIBRARY_PATH`. This in my testing was the most reliable and cleanest way
 to get these builds to work as well as be executable in-build.

-- 
Ticket URL: <https://trac.macports.org/ticket/58574#comment:79>
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