[Interest] building Qt [4.8.7 with gcc 5] and link-time optimisation

[René J. V. Bertin]

Thiago Macieira wrote:


> git clean -x -d -f in your sources.
> (you may want to back up your *.user files from Creator and restore)

That *was* a clean build; Qt 5.4.2 using the release tarball, freshly unpacked 
etc.

Patching the toplevel Makefile so that the QMAKE variable includes the -config 
ltcg arguments seems to work for me (I'm running these experiments from a 
MacPorts Portfile). Now to see if I cannot simply patch the configure script so it 
does the work for me. I'm a bit surprised that the configure script doesn't have 
such a feature yet, apparently.

>> And actually, I'm now fooling around with a project that just builds qtbase
>> (5.4.2), and it seems that I need -r even immediately after calling
>> configure.
> 
> configure should generate exactly one Makefile: the top-level.

I think that's what it does, but calling qmake -config ltcg immediately after 
configure doesn't appear to have any effect.

R