[MacPorts] #55471: Use separate portindexes for libc++ on older systems

[MacPorts]

#55471: Use separate portindexes for libc++ on older systems
--------------------------+----------------------------
  Reporter:  ryandesign   |      Owner:  neverpanic
      Type:  enhancement  |     Status:  assigned
  Priority:  Normal       |  Milestone:  MacPorts 2.5.0
 Component:  base         |    Version:
Resolution:               |   Keywords:
      Port:               |
--------------------------+----------------------------

Comment (by mojca):

 Ryan, I'm not sure if I know how to properly test this (I'm not 100% sure
 that I'm in fact patching the correct files).

 Here's the Portfile I'm testing
 {{{
 #!tcl
 PortSystem          1.0
 name                foo
 version             1.0
 categories          devel
 platforms           darwin

 if {${os.platform} eq "darwin" && ${os.major} > 10} {
     subport foo-bar {}
 }

 if {${cxx_stdlib} eq "libc++"} {
     subport foo-libcxx {}
 }
 }}}

 The result is
 {{{
 > portindex -p macosx_12_i386 -o PortIndex.12_i386
 Creating port index in /path/to/PortIndex.12_i386
 Adding port devel/foo
 Adding subport foo-bar
 Adding subport foo-libcxx
 }}}
 The second subport shouldn't have been there. But again, I might have not
 tested this correctly.

--
Ticket URL: <https://trac.macports.org/ticket/55471#comment:11>
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