kunit: tool: Build compile_commands.json

compile_commands.json is used by clangd[1] to provide code navigation
and completion functionality to editors. See [2] for an example
configuration that includes this functionality for VSCode.

It can currently be built manually when using kunit.py, by running:

  ./scripts/clang-tools/gen_compile_commands.py -d .kunit

With this change however, it's built automatically so you don't need to
manually keep it up to date.

Unlike the manual approach, having make build the compile_commands.json
means that it appears in the build output tree instead of at the root of
the source tree, so you'll need to add --compile-commands-dir= to your
clangd args for it to be found.

[1] https://clangd.llvm.org/
[2] https://github.com/FlorentRevest/linux-kernel-vscode

Signed-off-by: Brendan Jackman <jackmanb@google.com>
---
 tools/testing/kunit/kunit_kernel.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)


---
base-commit: 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4
change-id: 20240516-kunit-compile-commands-d994074fc2be

Best regards,

On Fri, 17 May 2024 at 03:38, Brendan Jackman <jackmanb@google.com> wrote:
>
> compile_commands.json is used by clangd[1] to provide code navigation
> and completion functionality to editors. See [2] for an example
> configuration that includes this functionality for VSCode.
>
> It can currently be built manually when using kunit.py, by running:
>
>   ./scripts/clang-tools/gen_compile_commands.py -d .kunit
>
> With this change however, it's built automatically so you don't need to
> manually keep it up to date.
>
> Unlike the manual approach, having make build the compile_commands.json
> means that it appears in the build output tree instead of at the root of
> the source tree, so you'll need to add --compile-commands-dir= to your
> clangd args for it to be found.
>
> [1] https://clangd.llvm.org/
> [2] https://github.com/FlorentRevest/linux-kernel-vscode
>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---

Sorry for missing this earlier.

I'm happy with this. Having the compile_commands.json be in the .kunit
directory is annoying, but it actually ends up being less annoying for
the case where you have lots of out-of-tree builds, so I actually
prefer it.

Reviewed-by: David Gow <davidgow@google.com>

Cheers,
-- David

>  tools/testing/kunit/kunit_kernel.py | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
> index 7254c110ff23..61931c4926fd 100644
> --- a/tools/testing/kunit/kunit_kernel.py
> +++ b/tools/testing/kunit/kunit_kernel.py
> @@ -72,7 +72,8 @@ class LinuxSourceTreeOperations:
>                         raise ConfigError(e.output.decode())
>
>         def make(self, jobs: int, build_dir: str, make_options: Optional[List[str]]) -> None:
> -               command = ['make', 'ARCH=' + self._linux_arch, 'O=' + build_dir, '--jobs=' + str(jobs)]
> +               command = ['make', 'all', 'compile_commands.json', 'ARCH=' + self._linux_arch,
> +                          'O=' + build_dir, '--jobs=' + str(jobs)]
>                 if make_options:
>                         command.extend(make_options)
>                 if self._cross_compile:
>
> ---
> base-commit: 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4
> change-id: 20240516-kunit-compile-commands-d994074fc2be
>
> Best regards,
> --
> Brendan Jackman <jackmanb@google.com>
>

On Thu, May 16, 2024 at 12:38 PM Brendan Jackman <jackmanb@google.com> wrote:
>
> compile_commands.json is used by clangd[1] to provide code navigation
> and completion functionality to editors. See [2] for an example
> configuration that includes this functionality for VSCode.
>
> It can currently be built manually when using kunit.py, by running:
>
>   ./scripts/clang-tools/gen_compile_commands.py -d .kunit
>
> With this change however, it's built automatically so you don't need to
> manually keep it up to date.

This is great!

>
> Unlike the manual approach, having make build the compile_commands.json
> means that it appears in the build output tree instead of at the root of
> the source tree, so you'll need to add --compile-commands-dir= to your
> clangd args for it to be found.

This is annoying for some. For my setup, the discovery of
compile_commands.json depends on where I open my editor from. So this
isn't really an issue as I can *choose* what compile_commands to use.
I think some folks may wish the compile_commands.json was also dumped
in the top-level directory so clangd can discover it easier.

>
> [1] https://clangd.llvm.org/
> [2] https://github.com/FlorentRevest/linux-kernel-vscode
>
> Signed-off-by: Brendan Jackman <jackmanb@google.com>
> ---
>  tools/testing/kunit/kunit_kernel.py | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
> index 7254c110ff23..61931c4926fd 100644
> --- a/tools/testing/kunit/kunit_kernel.py
> +++ b/tools/testing/kunit/kunit_kernel.py
> @@ -72,7 +72,8 @@ class LinuxSourceTreeOperations:
>                         raise ConfigError(e.output.decode())
>
>         def make(self, jobs: int, build_dir: str, make_options: Optional[List[str]]) -> None:
> -               command = ['make', 'ARCH=' + self._linux_arch, 'O=' + build_dir, '--jobs=' + str(jobs)]
> +               command = ['make', 'all', 'compile_commands.json', 'ARCH=' + self._linux_arch,
> +                          'O=' + build_dir, '--jobs=' + str(jobs)]
>                 if make_options:
>                         command.extend(make_options)
>                 if self._cross_compile:
>
> ---
> base-commit: 3c999d1ae3c75991902a1a7dad0cb62c2a3008b4
> change-id: 20240516-kunit-compile-commands-d994074fc2be
>
> Best regards,
> --
> Brendan Jackman <jackmanb@google.com>
>

Reviewed-by: Justin Stitt <justinstitt@google.com>

Thanks
Justin