In getDarwinDefines() (Targets.cpp:78), there is an assertion that prevent running if triple contains a micro version (like darwin 10.7.3 for instance).
line 124: assert(Rev == 0 && "invalid triple, unexpected micro version!");
This assertion is reached when invoking clang -cc1 without passing an explicit triple which should never append on normal usage, but it prevents running the clang test suite on some machine (like MacBook Pro 2011), as they are sold with a custom OS version.
Clang assert on all tests that do not explicitly specify a triple target (that is most tests).
Maybe the minor rev should be simply ignored and this assertion removed ?