Hi Matthias,

* Matthias Klose <doko@debian.org> [2022-06-17 10:18]:

The proposal is to turn on LTO by default on most 64bit release >architectures. Not proposing to do this on 32bit architectures because
of the limited address space at link time, and up to now nobody tested
LTO on 32bit archs. In test rebuilds, there were 373 packages
(dd-list in the wiki page) found not to build with link time
optimizations for various reasons. These range from easily fixable
issues in symbols files to some upstream issues. The idea is to fix
as many of these as possible, and then change the packaging for the
others to just turn off LTO in the package build.

In one of my packages, turning on LTO did not fail the build, but
exposed a dormant static initialization bug, as LTO apparently
messes with the initialization order [1]. I'd expect more bugs of
this kind to come up once LTO is enabled by default.

Cheers
Timo

[1] https://github.com/isl-org/Open3D/issues/4747

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