How to use clang-tidy?

[ClausKlein]

I am attempting to

I want to use run-clang-tidy if needed

Expected Behavior

No strange errors about missing header or bad compiler settings

Current Behavior

bash-5.2$ cmake --workflow appleclang-release 
Executing workflow step 1 of 3: configure preset "appleclang-release"

-- CMAKE_CXX_STANDARD="20" ; CMAKE_PROJECT_NAME="beman.exemplar" ; CMAKE_PROJECT_VERSION="2.1.1" ; CMAKE_SOURCE_DIR="/Users/clausklein/Workspace/cpp/beman-project/exemplar"
-- CMAKE_CXX_SCAN_FOR_MODULES="" ; PROJECT_NAME="beman.exemplar.examples" ; PROJECT_VERSION="2.1.1" ; PROJECT_SOURCE_DIR="/Users/clausklein/Workspace/cpp/beman-project/exemplar/examples"
-- Examples to be built: identity_direct_usage;identity_as_default_projection
-- Configuring done (0.9s)
-- Generating done (0.0s)
CMake Warning:
  Manually-specified variables were not used by the project:

    CMAKE_TOOLCHAIN_FILE


-- Build files have been written to: /Users/clausklein/Workspace/cpp/beman-project/exemplar/build/appleclang-release

Executing workflow step 2 of 3: build preset "appleclang-release"

ninja: no work to do.

Executing workflow step 3 of 3: test preset "appleclang-release"

Test project /Users/clausklein/Workspace/cpp/beman-project/exemplar/build/appleclang-release
    Start 1: IdentityTest.call_identity_with_int
1/7 Test #1: IdentityTest.call_identity_with_int ......................   Passed    0.00 sec
    Start 2: IdentityTest.call_identity_with_custom_type
2/7 Test #2: IdentityTest.call_identity_with_custom_type ..............   Passed    0.00 sec
    Start 3: IdentityTest.compare_std_vs_beman
3/7 Test #3: IdentityTest.compare_std_vs_beman ........................   Passed    0.00 sec
    Start 4: IdentityTest.check_is_transparent
4/7 Test #4: IdentityTest.check_is_transparent ........................   Passed    0.00 sec
    Start 5: find-package-test
5/7 Test #5: find-package-test ........................................   Passed    1.91 sec
    Start 6: beman.exemplar.examples.identity_direct_usage
6/7 Test #6: beman.exemplar.examples.identity_direct_usage ............   Passed    0.00 sec
    Start 7: beman.exemplar.examples.identity_as_default_projection
7/7 Test #7: beman.exemplar.examples.identity_as_default_projection ...   Passed    0.00 sec

100% tests passed, 0 tests failed out of 7

Total Test time (real) =   1.94 sec
bash-5.2$ clang-tidy -p=build/appleclang-release /Users/clausklein/Workspace/cpp/beman-project/exemplar/examples/identity_direct_usage.cpp
4 warnings and 1 error generated.
Error while processing /Users/clausklein/Workspace/cpp/beman-project/exemplar/examples/identity_direct_usage.cpp.
/Users/clausklein/Workspace/cpp/beman-project/exemplar/examples/identity_direct_usage.cpp:7:11: warning: namespace alias decl 'exe' is unused [misc-unused-alias-decls]
    7 | namespace exe = beman::exemplar;
      | ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
    8 | 
/Users/clausklein/Workspace/cpp/beman-project/exemplar/src/beman/exemplar/../../../include/beman/exemplar/identity.hpp:23:10: error: 'utility' file not found [clang-diagnostic-error]
   23 | #include <utility> // std::forward
      |          ^~~~~~~~~
Suppressed 3 warnings (3 in non-user code).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
Found compiler error(s).
bash-5.2$ 

Additional Discussions

Which clang-tidy checks should be used?

[wusatosi]

Using clang-tidy is not officially supported in exemplar.
I am also against clang-tidy, I think it's way to verbose and noisy, see previous comment: bemanproject/inplace_vector#43 (comment)

I think it's clear from experience that if excessive diagnosis is provided, folks will just // linter: off.

[ClausKlein]

Do you think that should be ignored?

Running clang-tidy for 3 files out of 114 in compilation database ...
[1/3][6.8s] /usr/local/Cellar/llvm/20.1.5/bin/clang-tidy -p=build/appleclang-release /Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp
/Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp:9:11: warning: namespace alias decl 'scope' is unused [misc-unused-alias-decls]
    9 | namespace scope = beman::scope;
      | ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
   10 | 
/Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp:11:6: warning: function 'print_exit_status' can be made static or moved into an anonymous namespace to enforce internal linkage [misc-use-internal-linkage]
   11 | void print_exit_status(std::string_view name, bool exit_status, bool did_throw) {
      |      ^
      | static 
/Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp:18:6: warning: function 'maybe_throw' can be made static or moved into an anonymous namespace to enforce internal linkage [misc-use-internal-linkage]
   18 | void maybe_throw() {
      |      ^
      | static 
/Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp:19:9: warning: rand() has limited randomness; use C++11 random library instead [cert-msc30-c,cert-msc50-cpp]
   19 |     if (std::rand() >= RAND_MAX / 2)
      |         ^
/Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp:19:37: warning: statement should be inside braces [hicpp-braces-around-statements]
   19 |     if (std::rand() >= RAND_MAX / 2)
      |                                     ^
      |                                      {
   20 |         throw std::exception{};
      |                                
/Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp:24:5: warning: multiple declarations in a single statement reduces readability [readability-isolate-declaration]
   24 |     bool exit_status{false}, did_throw{false};
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/Users/clausklein/Workspace/cpp/cxx23/scope/include/beman/scope/scope.hpp:18:10: error: 'experimental/scope' file not found [clang-diagnostic-error]
   18 | #include <experimental/scope> //todo unconditional for unique_resource
      |          ^~~~~~~~~~~~~~~~~~~~
95317 warnings and 1 error generated.
Error while processing /Users/clausklein/Workspace/cpp/cxx23/scope/examples/scope_example.cpp.
Suppressed 95311 warnings (95310 in non-user code, 1 NOLINT).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
Found compiler error(s).

[wusatosi]

Let's derive a sane set of clang tidy rules to adopt.

[JeffGarland]

Picking this back up. I think it would be valuable to have clang-tidy as a tool for developers, users and CI. Could we do something like adopt this cmake setup https://github.com/jkammerland/clang-tidy.cmake so that it's at least an option for folks to enable? We could take a project as a guinea pig to test it out before adding it to exemplar. @ClausKlein I'd entertain a PR in the scope repo to explore adding it.