[Interest] Qt 5 LTO build on OS X 10.9 (and earlier)

[René J. V. Bertin]

Thiago Macieira wrote:

> No, just like Qt won't pick up gcc-4.8, clang-3.5 or gcc-ar-4.9. You must
> provide a PATH entry that contains the binaries without suffix or you'll have
> to tinker with the mkspec (QMAKE_AR).

QMAKE_AR_LTCG in fact (and QMAKE_NM_LTCG, QMAKE_RANLIB_LTCG). On OS X that also 
means tinkering with mac/sdk.prf to ensure that xcrun isn't used to undo any 
compiler selection you'd make in one of "the usual ways".

About using alternate compilers: I haven't yet figured out how to get qmake to 
build using the compiler of choice, as well as the config tests. For qmake the 
compiler choice probably doesn't make a lot of difference, but the config tests 
probably best be done with the compiler that's used to do the actual build, 
don't you think?

R.