Am 2023-02-28 01:39, schrieb Steve Langasek:
[some precursor
I can see that for bootstrapping a new architecture, it will sometimes
be
useful to use a toolchain newer than the one that is currently default
in
Debian, and as a result it is useful to also be able to bypass new
stricter
-Werror behavior from gcc upstream that breaks compatibility with
existing
code.
I agree, this is one use case.
It isn't clear to me from the discussion history that this is the
actual use
case at issue. But supposing it is, that's one use case; and it's a
use
case that can be addressed without having to make any per-package
changes
and without having to make any changes to dpkg-buildflags interfaces by
exporting
DEB_CFLAGS_APPEND=-Wno-error
DEB_CXXFLAGS_APPEND=-Wno-error
as part of the bootstrap build environment, for all packages.
Now, if all packages would just use the flags from dpkg-buildflags as
is,
or as the final part of CFLAGS/CXXFLAGS, that would be nice. However,
IME,
that is not always the case and some maintainers append -Werror in
particular.
Of course, dpkg-buildflags also exports flags for other languages than
C and
C++ (and should do), so if you want to have full package coverage you
would
want your set of _APPEND variables to match the set of per-language
flags
that dpkg-buildflags already handles. Having to export 7 variables
instead
of 1 is annoying. But it also doesn't require reaching consensus on a
new
interface in dpkg. And I remain unconvinced that the particular
proposed
interface is the right way around for Debian at large.
Following this discussion, I fear we might not reach consensus. But my
ideal
(strong) suggestion to package maintainers would be:
1) Don't use -Werror (or equivalent for your packages language) during
normal
builds (i.e. on buildd)
2) Do use -Werror via some mechanism (DEB_CFLAGS_APPEND)? during CI
builds
3) Actually utilize CI builds to detect any breakages early.
(1) helps in multiple cases, all of which are rebuilds of some sort.
Security: Minimize the patch to the package if the compiler was updated
since
your package was last built.
Derived distros: I see this quite regularly at Google - packages not
rebuilt
in Debian for months, now fail to build with newer gcc. While we use
testing
as our base (so usually not *too* far off from unstable), we do rebuild
packages
in testing more often than Debian would. Not strictly necessary in most
cases,
but most of the time, if package bar build-depends on libfoo-dev and
that gets
an update, bar will usually be rebuilt (not always, but whatever).
Porting (as mentioned by Steve and others) - Porting to other
architectures
often requires a different (newer) compiler version, which might lead to
failures with -Werror.
Cheers,
Sven
