[MacPorts] #66246: Help needed: something forces -stdlib= flag which breaks build with GCC

[MacPorts]

#66246: Help needed: something forces -stdlib= flag which breaks build with GCC
--------------------------+----------------------
 Reporter:  barracuda156  |      Owner:  kencu
     Type:  defect        |     Status:  assigned
 Priority:  Normal        |  Milestone:
Component:  ports         |    Version:  2.8.0
 Keywords:                |       Port:
--------------------------+----------------------
 Trying to build my own port, OpenCoarrays, and it fails at configure; I
 cannot figure out where this comes from:
 {{{
     gcc-mp-12: error: unrecognized command-line option '-stdlib=libc++'
     make[1]: *** [cmTC_d357f] Error 1
     make: *** [cmTC_d357f/fast] Error 2
 }}}

 Cmake cache has:
 {{{
 CMAKE_EXE_LINKER_FLAGS:STRING=-L/opt/local/lib
 -Wl,-headerpad_max_install_names -latomic -stdlib=libc++
 -Wl,-rpath,/opt/local/lib/libgcc
 }}}

 But it is defined neither in the source nor in portfile (at least I cannot
 find anything relevant). I tried cutting out every mention of this flag in
 compilers PG and mpi PG, to no avail.

 (This flag, likely, should not be forced at all, but definitely not on
 PPC.)

-- 
Ticket URL: <https://trac.macports.org/ticket/66246>
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