[MacPorts] #30041: Provide API for compiler blacklisting/whitelisting

[MacPorts]

#30041: Provide API for compiler blacklisting/whitelisting
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 Reporter:  jeremyhu@…             |       Owner:  macports-tickets@…                   
     Type:  defect                 |      Status:  new                                  
 Priority:  Normal                 |   Milestone:                                       
Component:  base                   |     Version:  1.9.2                                
 Keywords:                         |        Port:                                       
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 It would be nice if there were an API for easily blacklisting or
 whitelisting compilers in individual ports.

 If a port lists a whitelist, the first available compiler in the whitelist
 would be used.  If none is available, the first listed one available from
 MacPorts should be built and used.

 If a port lists a blacklist, the current compiler is used as long as it's
 not in the blacklist.  If it is in the blacklist, the first listed one in
 the fallback list is used.  if none is available, the first listed one
 available from Macports should be built and used.

 PseudoCode:

 {{{
 if whitelist
   if default compiler is in whitelist
     return default compiler
   if whitelist contains an available compiler
     return first available compiler in whitelist
   if whitelist contains a MacPorts compiler
     add first MacPorts compiler to depends_build
     return first MacPorts compiler
   return NULL

 if blacklist
   if default compiler is NOT in blacklist
     return default compiler
   if fallback contains an available compiler
     return first available compiler in fallback
   if fallback contains a MacPorts compiler
     add first MacPorts compiler to depends_build
     return first MacPorts compiler
   return NULL

 return default compiler
 }}}

 We could do something like this:

 {{{
 compiler.blacklist           {llvm-gcc-4.2 clang macports-clang}
 compiler.blacklist_fallback  {gcc-4.2 apple-gcc-4.2 macports-gcc-4.6
 macports-gcc-4.5 macports-gcc-4.4 macports-gcc-4.3}
 }}}

 This would result in using gcc-4.2 if available and *building* gcc-4.2 if
 not.

-- 
Ticket URL: <https://trac.macports.org/ticket/30041>
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