carbon-lang/.clang-tidy

# Part of the Carbon Language project, under the Apache License v2.0 with LLVM
# Exceptions. See /LICENSE for license information.
# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

---
# Get colors when outputting through `bazel build --config=clang-tidy`.
UseColor: true
# This is necessary for `--config=clang-tidy` to catch errors.
WarningsAsErrors: '*'

Checks:
  # We turn on all of a few categories by default.
  - '-*'
  - 'bugprone-*'
  - 'google-*'
  - 'modernize-*'
  - 'performance-*'
  - 'readability-*'

  # `misc` is selectively enabled because we want a minority of them.
  - 'misc-definitions-in-headers'
  - 'misc-misplaced-const'
  - 'misc-redundant-expression'
  - 'misc-static-assert'
  - 'misc-unconventional-assign-operator'
  - 'misc-uniqueptr-reset-release'
  - 'misc-unused-*'

  # Disabled due to the implied style choices.
  - '-modernize-return-braced-init-list'
  - '-modernize-use-default-member-init'
  - '-modernize-use-emplace'
  - '-readability-convert-member-functions-to-static'
  - '-readability-else-after-return'
  - '-readability-identifier-length'
  - '-readability-implicit-bool-conversion'
  - '-readability-make-member-function-const'
  - '-readability-static-definition-in-anonymous-namespace'
  - '-readability-use-anyofallof'

  # Warns when we have multiple empty cases in switches, which we do for comment
  # reasons.
  - '-bugprone-branch-clone'
  # Frequently warns on multiple parameters of the same type.
  - '-bugprone-easily-swappable-parameters'
  # Finds issues like out-of-memory in main(). We don't use exceptions, so it's
  # unlikely to find real issues.
  - '-bugprone-exception-escape'
  # Has false positives in places such as using an argument to declare a name,
  # which cannot have parentheses. For our limited use of macros, this is a
  # common conflict.
  - '-bugprone-macro-parentheses'
  # Conflicts with integer type C++ style.
  - '-bugprone-narrowing-conversions'
  # Has false positives for `enum_base.h`. Clang's built-in switch warnings
  # cover most of our risk of bugs here.
  - '-bugprone-switch-missing-default-case'
  # In clang-tidy 16, has false positives on code like:
  #     while (auto name_ref = insts().Get(inst_id).TryAs<SemIR::NameRef>()) {
  #       inst_id = name_ref->value_id;
  #                 ^ unchecked access to optional value
  #     }
  - '-bugprone-unchecked-optional-access'
  # Overlaps with `readability-function-size`.
  - '-google-readability-function-size'
  # Suggests usernames on TODOs, which we don't want.
  - '-google-readability-todo'
  # Suggests `std::array`, which we could migrate to, but conflicts with the
  # status quo.
  - '-modernize-avoid-c-arrays'
  # Warns on creation of SemIR typed insts, for which we do not currently want
  # to use designated initialization.
  - '-modernize-use-designated-initializers'
  # Only fixes const methods, not non-const, which yields distracting results on
  # accessors.
  - '-modernize-use-nodiscard'
  # Duplicates `modernize-pass-by-value`.
  - '-performance-unnecessary-value-param'
  # Warns on enums which use the `LastValue = Value` pattern if all the other
  # discriminants aren't given an explicit value.
  - '-readability-enum-initial-value'
  # Warns too frequently.
  - '-readability-function-cognitive-complexity'
  # Warns in reasonably documented situations.
  - '-readability-magic-numbers'
  # Warns on `= {}` which is also used to indicate which fields do not need to
  # be explicitly initialized in aggregate initialization.
  - '-readability-redundant-member-init'
  # Warns when callers use similar names as different parameters.
  - '-readability-suspicious-call-argument'
CheckOptions:
  - key: readability-identifier-naming.ClassCase
    value: CamelCase
  - key: readability-identifier-naming.ClassConstantCase
    value: CamelCase
  - key: readability-identifier-naming.ConstexprVariableCase
    value: CamelCase
  - key: readability-identifier-naming.NamespaceCase
    value: CamelCase
  - key: readability-identifier-naming.StructCase
    value: CamelCase
  - key: readability-identifier-naming.TemplateParameterCase
    value: CamelCase
  - key: readability-identifier-naming.TypeAliasCase
    value: CamelCase
  - key: readability-identifier-naming.TypedefCase
    value: CamelCase
  - key: readability-identifier-naming.UnionCase
    value: CamelCase
  - key: readability-identifier-naming.ClassMemberCase
    value: lower_case
  - key: readability-identifier-naming.ParameterCase
    value: lower_case
  - key: readability-identifier-naming.VariableCase
    value: lower_case
  - key: readability-identifier-naming.MethodIgnoredRegexp
    value: '^classof$'
  # This erroneously fires in C++20 mode with LLVM 16 clang-tidy, due to:
  # https://github.com/llvm/llvm-project/issues/46097
  - key: readability-identifier-naming.TemplateParameterIgnoredRegexp
    value: '^expr-type$'