cppunit @1.14.0 should fallback to a MacPorts gcc if no system c++11 compliant compiler is being found

[udbraumann]

When upgrading cppunit to 1.14.0 I realized this trouble:

$ sudo port build cppunit
--->  Computing dependencies for cppunitWarning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option
Warning: All compilers are either blacklisted or unavailable; defaulting to first fallback option

Error: Cannot install clang-4.0 for the arch 'powerpc' because
Error: its dependency libxml2 does not build for the required arch by default
Error: and the configured universal_archs 'i386 ppc' are not sufficient.
Error: Follow https://guide.macports.org/#project.tickets to report a bug.
Error: Processing of port cppunit failed

I think it is not a good solution to set clang-4.0 as fallback if the system (e.g. 10.5.8) has no XCode compiler supporting c++11, as long as MacPorts gcc (e.g. gcc-4.8 or newer) is sufficient for the c++11 compliance. Once I called

sudo port upgrade cppunit configure.compiler=macports-gcc-4.8

I could smoothly build cppunit.

BTW, with the present configuration cppunit is not even being downloaded if the search for a c++11 compliant compiler fails. For the problem description above I already had run the line with the workaround before.

[kencu (Ken)]

the cxx11 1.1 portgroup could be fancier about whitelisting compilers, if it considered what compilers are possible to build on certain OS versions.

It would be truly nice if it whitelisted a suitable compiler that you already have installed, of course, rather than forcing one you don't have.

I know full well it doesn't work this way at present. I wonder if the compilers portgroup could help give it some cleverness...

[michaelld (Michael Dickens)]

Ditto what Ken wrote ... I'd love to see some "smarts" added to dependencies, variants, and compilers. The former 2 kinda have that; good enough at least for now even if awkward. I don't know about the latter one but I do believe that Ken should know ... it would be an awesome feature IMHO!

[michaelld (Michael Dickens)]

In the interim since ~2 years ago with the last comment, we've fixed GCC5 & GCC6 to build cleanly on PPC and deliver a C++11 compliant compiler. Hence, this ticket's issue is, in my opinion, no longer relevant && I'm closing it as fixed. If anyone objects, please reopen and post what's going on & why the ticket is still relevant.