Bug#1029010: llvm-toolchain-15: autopkgtest regression

[Simon McVittie]

On Fri, 03 Mar 2023 at 17:41:22 +0100, Sylvestre Ledru wrote:
> Le 16/01/2023 à 16:44, Adrian Bunk a écrit :
> > /usr/include/wasm32-wasi/c++/v1/__type_traits/is_array.h:40:22: error: reference to unresolved using declaration
> > template <class _Tp, size_t _Np> struct _LIBCPP_TEMPLATE_VIS is_array<_Tp[_Np]>
> >                       ^
> > /usr/include/wasm32-wasi/c++/v1/cstddef:52:1: note: using declaration annotated with 'using_if_exists' here
> > using ::size_t _LIBCPP_USING_IF_EXISTS;

I've cut down what I think is the root cause of this compile failure to
a more minimal bug report: see #1032317.

I don't think this is *really* a regression, because in the version in
bookworm, the autopkgtest didn't exercise compilation of C++ into
WebAssembly at all.

If I understand correctly, when compared with bookworm, the version in
sid adds a new feature (the necessary -dev packages for compiling C++ into
WebAssembly) and also adds a smoke-test for that feature, but the feature
doesn't yet work as intended. Is that accurate?

Did the new autopkgtest coverage pass on the maintainers' systems? I don't
seen any sign of it having passed on ci.debian.net since 1:15.0.6-5~exp1
(see https://ci.debian.net/packages/l/llvm-toolchain-15/unstable/amd64/
which includes test results with all packages from unstable, and also test
results with llvm-toolchain-15 taken from experimental and everything else
from unstable).

If you don't consider full C++ wasm support to be release-critical for
bookworm, one option would be to remove the packages that enable it,
together with their test coverage; that should get the autopkgtest passing
again. However, I haven't looked at the diff between 15.0.6 and 15.0.7,
so I don't know whether the release team would be likely to accept an
unblock request or not.

When enabling new features in experimental, please check the CI results
before re-uploading to unstable. This can be done conveniently via
<https://qa.debian.org/excuses.php?experimental=1&package=llvm-toolchain-15>,
which asks the question: if the packages in unstable were all in
testing, and the packages in experimental were all in unstable, would
llvm-toolchain-15 be able to migrate?

Thanks,
    smcv