ci: use clang-16 in tidy task #27404

Follow up to #27311 (comment), as IWYU now has a clang_16 branch.

This also removes some workarounds for (now fixed) clang-tidy issues, and simplifies the IWYU install steps.

<!--e57a25ab6845829454e8d69fc972939a-->

The following sections might be updated with supplementary metadata relevant to reviewers and maintainers.

<!--021abf342d371248e50ceaed478a90ca-->

Reviews

See the guideline for information on the review process.

If your review is incorrectly listed, please react with 👎 to this comment and the bot will ignore it on the next update.

<!--174a7506f384e20aa4161008e828411d-->

Conflicts

Reviewers, this pull request conflicts with the following ones:

• #27340 (ci: Use Cirrus CI dockerfile env by MarcoFalke)
• #25797 (build: Add CMake-based build system by hebasto)

If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

Concept ACK.

Note that even though the CI here is "green", the tidy task has failed:

In file included from common/url.cpp:5:
In file included from ./common/url.h:8:
In file included from /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/string:40:
In file included from /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/bits/char_traits.h:39:
In file included from /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/bits/postypes.h:40:
In file included from /usr/lib/gcc/x86_64-linux-gnu/12/../../../../include/c++/12/cwchar:44:
/usr/include/wchar.h:35:10: fatal error: 'stddef.h' file not found
#include <stddef.h>
         ^~~~~~~~~~

FWIW, on a local Ubuntu 23.04 installation, I have no issues with running the IWYU tool manually.

/usr/include/wchar.h:35:10: fatal error: 'stddef.h' file not found
#include <stddef.h>
         ^~~~~~~~~~

This error can be fixed with the following diff:

--- a/ci/test/00_setup_env_native_tidy.sh
+++ b/ci/test/00_setup_env_native_tidy.sh
@@ -15,5 +15,5 @@ export RUN_FUNCTIONAL_TESTS=false
 export RUN_FUZZ_TESTS=false
 export RUN_TIDY=true
 export GOAL="install"
-export BITCOIN_CONFIG="CC=clang-16 CXX=clang++-16 --with-incompatible-bdb --disable-hardening CFLAGS='-O0 -g0' CXXFLAGS='-O0 -g0'"
+export BITCOIN_CONFIG="CC=clang-16 CXX=clang++-16 --with-incompatible-bdb --disable-hardening CFLAGS='-O0 -g0' CXXFLAGS='-O0 -g0 -I/usr/lib/llvm-16/lib/clang/16/include'"
 export CCACHE_SIZE=200M

See: https://cirrus-ci.com/task/5852229609979904

Some related discussion see in https://github.com/include-what-you-use/include-what-you-use/issues/679.

Note that even though the CI here is "green", the tidy task has failed

#26763 is somewhat related.

This error can be fixed with the following diff:

I wonder if another workaround would be to use libc++, but I haven't checked if the iwyu output is better or worse with libc++.

Also #25466 (review)

-I/usr/lib/llvm-16/lib/clang/16/include

Included this. I think we could merge this as-is, but should also figure out why it's needed. It feels like there is another issue here.

Also #25466 (review)

Removed the related suppressions.

ACK a56c96507a9e943bbcd7e126bc827de9495f0ebd

lgtm ACK a56c96507a9e943bbcd7e126bc827de9495f0ebd

ACK https://github.com/bitcoin/bitcoin/pull/27404/commits/a56c96507a9e943bbcd7e126bc827de9495f0ebd

Included this. I think we could merge this as-is, but should also figure out why it's needed. It feels like there is another issue here.

did a little digging and found this: https://github.com/include-what-you-use/include-what-you-use/issues/679#issuecomment-482798379 , which seems to still be an issue based on the discussion in the linked solution. fwiw, the fix you have here seems to be one of the preferred ways of dealing with this