build: implement clang-tidy using our plugin

The principle of this is that you can either externally build it with
Nix (actual implementation will be in a future commit), or it can be
built with meson if the Nix one is not passed in.

The idea I have is that dev shells don't receive the one from Nix to
avoid having to build it, but CI can use the one from Nix and save some
gratuitous rebuilds.

The design of this is that you can run `ninja -C build clang-tidy` and
it will simply correctly clang-tidy the codebase in spite of PCH
bullshit caused by the cc-wrapper.

This is a truly horrendous number of hacks in a ball, caused by bugs in
several pieces of software, and I am not even getting started.

I don't consider this to fix the clang-tidy issue filing, since we still
have a fair number of issues to fix even on the existing minimal
configuration, and I have not yet implemented it in CI. Realistically we
will need to do something like https://github.com/Ericsson/codechecker
to be able to silence warnings without physically touching the code, or
at least *diff* reports between versions.

Also, the run-clang-tidy output design is rather atrocious and must
not be inflicted upon anyone I have respect for, since it buries the
diagnostics in a pile of invocation logs. We would do really well to
integrate with the Gerrit SARIF stuff so we can dump the reports on
people in a user-friendly manner.

Related: https://git.lix.systems/lix-project/lix/issues/147

Change-Id: Ifefe533f3b56874795de231667046b2da6ff2461

1 files changed, 6 insertions, 2 deletions

diff --git a/meson.options b/meson.options
index fc2050809..679d88347 100644
--- a/meson.options
+++ b/meson.options
@@ -1,7 +1,7 @@
 # vim: filetype=meson
 
 option('enable-build', type : 'boolean', value : true,
-  description : 'Set to false to not actually build. Only really makes sense with -Dinternal-api-docs=true',
+  description : 'set to false to not actually build. Only really makes sense with -Dinternal-api-docs=true',
 )
 
 option('gc', type : 'feature',
@@ -37,7 +37,7 @@ option('tests-brief', type : 'boolean', value : false,
 )
 
 option('profile-build', type : 'feature', value: 'disabled',
-  description : 'whether to enable -ftime-trace in clang builds, allowing for speeding up the build.'
+  description : 'whether to enable -ftime-trace in clang builds, allowing for diagnosing the cause of build time.'
 )
 
 option('store-dir', type : 'string', value : '/nix/store',
@@ -68,3 +68,7 @@ option('profile-dir', type : 'string', value : 'etc/profile.d',
 option('enable-pch-std', type : 'boolean', value : true,
   description : 'whether to use precompiled headers for C++\'s standard library (breaks clangd if you\'re using GCC)',
 )
+
+option('lix-clang-tidy-checks-path', type : 'string', value : '',
+  description: 'path to lix-clang-tidy-checks library file, if providing it externally. Uses an internal one if this is not set',
+)