[MacPorts] #68962: libplacebo broken with the latest update

[MacPorts]

#68962: libplacebo broken with the latest update
---------------------------+-----------------------------------------
  Reporter:  barracuda156  |      Owner:  i0ntempest
      Type:  defect        |     Status:  assigned
  Priority:  Normal        |  Milestone:
 Component:  ports         |    Version:  2.8.1
Resolution:                |   Keywords:  tiger, leopard, snowleopard
      Port:  libplacebo    |
---------------------------+-----------------------------------------

Comment (by kencu):

 the build failure on the 10.6 buildbot is exposing a bug with
 legacysupport's newer libcxx forcing....it has nothing to do with this
 port specifically.

 it looks like this "C" build line has a bunch of cxx-specific stuff on it,
 and no surprise I guess it ultimately fails running across cxx code.

 Why are the cxx flags showing up on the "C" build?

 Well, it's because  legacysupport is  putting all the cxx-specific
 modifications onto the CPP flags for some reason, instead of the CXX
 flags, and so the C builds are picking them up.

 {{{
 CPPFLAGS='-isystem/opt/local/include/libcxx/v1 -nostdinc++
 -isystem/opt/local/include/LegacySupport -I/opt/local/include'
 }}}

 this is just wrong. It may not have showed up before because not many
 builds are mixing C and C++ code and also requiring legacysupport's newer
 libcxx.

 {{{
 /opt/local/bin/clang-mp-11 -Isrc/libplacebo.338.dylib.p -Isrc
 -I../libplacebo-6.338.1/src -Isrc/include
 -I../libplacebo-6.338.1/src/include -Isrc/opengl/include
 -I../libplacebo-6.338.1/src/opengl/include -Isrc/shaders -Isrc/vulkan
 -Isrc/opengl/include/glad -I/opt/local/include -fvisibility=hidden
 -fdiagnostics-color=always -Wall -Winvalid-pch -Wextra -std=c11 -O2 -g
 -Wundef -Wshadow -Wparentheses -Wpointer-arith -fno-math-errno
 -D_ISOC99_SOURCE -D_ISOC11_SOURCE -D_GNU_SOURCE -U__STRICT_ANSI__
 -Wmissing-prototypes -Wno-sign-compare -Wno-unused-parameter -Wno-missing-
 field-initializers -Wno-type-limits -Werror=implicit-function-declaration
 -Werror=incompatible-pointer-types -Wno-missing-braces -Wundef -Wshadow
 -Wparentheses -Wpointer-arith -fno-math-errno -pipe -Os -arch x86_64
 -nostdinc++ -DPL_HAVE_PTHREAD '' -DPL_EXPORT -MD -MQ
 src/libplacebo.338.dylib.p/meson-generated_.._shaders.c.o -MF
 src/libplacebo.338.dylib.p/meson-generated_.._shaders.c.o.d -o
 src/libplacebo.338.dylib.p/meson-generated_.._shaders.c.o -c src/shaders.c
 In file included from src/shaders.c:19:
 In file included from /opt/local/include/LegacySupport/math.h:77:
 /opt/local/include/libcxx/v1/math.h:316:8: error: expected identifier or
 '('
 extern "C" {
        ^
 }}}

 This probably means "we" need to go back and sort out properly how to add
 these flags.

-- 
Ticket URL: <https://trac.macports.org/ticket/68962#comment:1>
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