llvm-3.4: Circular dependencies / dependency cycle

[ryandesign (Ryan Carsten Schmidt)]

A dependency cycle exists involving llvm-3.4 on Mac OS X 10.6 again. Some dependency of llvm-3.4 depends on clang-3.4.

Consequence: When I try to upgrade outdated ports, clang-3.4 gets built before llvm-3.4, which crashes because the outdated llvm-3.4 is linked with an old libffi.dylib which no longer exists.

[ryandesign (Ryan Carsten Schmidt)]

$ sudo port upgrade clang-3.4
--->  Computing dependencies for gettext-runtime
The following dependencies will be installed: 
 clang-3.4
 clang-3.4
Continue? [Y/n]: 

[ryandesign (Ryan Carsten Schmidt)]

llvm-3.4 depends on perl5 which depends on perl5.28 which depends on xz and clang-3.7 both of which depend on clang-3.4 which depends on llvm-3.4.

The perl5 dependency is declared as bin:perl:perl5 so you might think that the system's perl being present would satisfy it, however the perl5 port is also installed, so I think its dependencies are getting included in the calculation.

If I remove bin:perl:perl5 from llvm-3.4's dependencies the problem goes away.