Project:Toolchain/LTO

Plan

 * Add  to  (done, see  )
 * Trivial glob is a bit messy but also matches stuff like -fno-lto, hence this is needed (e.g. )
 * Needs to handle non-obvious flags which require LTO (e.g. )


 * Review blockers of the LTO tracker and fix appropriately


 * Review list of failures from the gentooLTO overlay and fix appropriately


 * Formulate a policy on USE=lto
 * Likely will mean "workarounds are needed in build system" and not "upstream support LTO for this package"
 * How can we express the latter though? Many of us would be happy using LTO where we know upstream support it
 * See https://marc.info/?l=gentoo-project&m=161957141921902&w=2

Signs a package is unsafe

 * Serious warnings which indicate runtime issues
 * Any  warnings
 * Any  warnings
 * Any  warnings
 * Test failures with LTO but passes without
 * Failure to build with e.g. multiple LTO partitions

Other distros

 * Debian plans to default to LTO either for bookworm or bookworm+1.


 * Fedora has defaulted to LTO since Fedora 33 (2021)
 * https://fedoraproject.org/wiki/LTOByDefault
 * https://fedoraproject.org/wiki/Changes/LTOBuildImprovements


 * openSUSE defaulted to LTO in 2019
 * https://lists.opensuse.org/archives/list/factory@lists.opensuse.org/message/UT2YVWPZK2IZ5EUHMSHNCW3Q72CMPWCJ/