[MacPorts] #58741: get clang 3.4 and 3.9 4.0 5.0"back"

[MacPorts]

#58741: get clang 3.4 and 3.9 4.0 5.0"back"
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 Reporter:  rmottola  |      Owner:  (none)
     Type:  defect    |     Status:  new
 Priority:  Normal    |  Milestone:
Component:  ports     |    Version:
 Keywords:  clang     |       Port:  clang
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 recently clang 8.0 has been marked a replacement for older compilers.
 This is not true generally: when Mac SDK code is used, too new compilers
 cause issues, so on 10.6 Snow Leopard, for example 3.9 is a very good
 compromise, as is clang 5.0 too.
 Clang 8.0 is just "too new". For non-Mac code this is different and newer
 compilers are fine
 (Same applies for GCC, btw, using gcc6 or gcc8 causes issues!)

 Ken maybe has more experience, but I think 3.9 is useful to retain.
 Also, it is difficult to bootstrap these compilers, so to get 8.0 I needed
 3.9, but I needed to get 3.4 which is the "source".
 Similar experiences on 10.7 or 10.5, just with different limits. On 10.5 I
 use 3.4 and 3.7, wanting to get 3.9 and 5.0 actually

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Ticket URL: <https://trac.macports.org/ticket/58741>
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