Is it possible to ignore a header with clang-tidy

Question

I want to include a header from an external project, but clang-tidy is quite unhappy about it and produces a huge list of warnings. To workaround this, I am trying to disable all diagnostics coming from this header.

I tried:

// NOLINTBEGIN
// NOLINTNEXTLINE
#include <bad.hpp> // NOLINT
// NOLINTEND

But this does not work unfortunately.

This email thread suggests to use -header-filter (HeaderFilterRegex) option.

HeaderFilterRegex: '^((?!bad.hpp).)*$'

But this results into all headers being ignored, since clang tidy uses POSIX regex syntax. Which does not support negative look ahead.

I also considered using line-filter for this as this answer suggests, but there is no such option for the config file.

Is it possible at all?

Answer 1

May 2024

Yet unreleased clang-tidy from llvm-19 supports headers filtering. According to the documentation, one can use --exclude-header-filter flag or ExcludeHeaderFilterRegex option to filter out unwanted headers:

  --exclude-header-filter=<string> - Regular expression matching the names of the
                                     headers to exclude diagnostics from. Diagnostics
                                     from the main file of each translation unit are
                                     always displayed.
                                     Must be used together with --header-filter.
                                     Can be used together with -line-filter.
                                     This option overrides the 'ExcludeHeaderFilterRegex'
                                     option in .clang-tidy file, if any.

April 2022

As of today (Apr 19 2022), this thread on disclosure llvm blog suggests that the feature is not supported.

Relevant notes are:

• HeaderFilterRegex is parsed using llvm::Regex, which does not support negative lookahead.
• Using std::regex instead of llvm::Regex is not possible yet, as some compilers do not have std::regex support. Future versions of clang-tidy may implement glob based file names filtering.

I can see only two possible workarounds for this now:

• List all the allowed paths in HeaderFilterRegex.
• Patch clang-tidy to use std::regex and use your own version.