Re: [PATCH] gcc: fix buildpaths QA with LTO

[Patrick Williams <patrick@stwcx.xyz>]

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On Wed, Mar 25, 2026 at 07:39:51AM -0400, Patrick Williams wrote:
> When LTO is enabled, due to a gcc bug[1], the linker needs the same
> flags in DEBUG_PREFIX_MAP as the compiler.  Without this the buildpaths
> QA failure can occur due to unstripped build directory strings in the
> DWARF data.
> 
> With GCC 15.2 this can be noticed by setting many meson-built packages,
> such as systemd, with:
> 
>     EXTRA_OEMESON:append:class-target = " -Db_lto=true"
> 
> Add the DEBUG_PREFIX_MAP to the TARGET_LDFLAGS for gcc.
> 
> While the lto.inc enables LTO across the whole image, some packages
> either manually enable LTO on their own or downstream recipe
> maintainers have explicitly set LTO in specific packages, so it is not
> sufficient to set this in lto.inc only.
> 
> [1]: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109805
> 
> Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
> ---

A few other mailing list threads also talk about this problem.

One alternative is to re-add it to the TARGET_LDFLAGS in bitbake.conf by
reverting 1797741aad02b8bf429fac4b81e30cdda64b5448 [1], but that seems to
have problems for cgo applications which might be resolved by another
patch[2].  Adding to lto.inc[3] isn't sufficient for the reasons I
mentioned above.

[1]: https://lore.kernel.org/openembedded-core/20260122194959.13457-2-rs@ti.com/#t
[2]: https://lore.kernel.org/openembedded-core/20260127170344.2960247-2-rs@ti.com/
[3]: https://lore.kernel.org/openembedded-core/20260204052638.284617-1-changqing.li@windriver.com/
-- 
Patrick Williams

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