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[clang-tidy] Add new check: readability-use-concise-preprocessor-directives (#146830)
Closes #132561. This is a check that rewrites `#if`s and `#elif`s like so: ```cpp #if defined(MEOW) // -> #ifdef MEOW #if !defined(MEOW) // -> #ifndef MEOW ``` And, since C23 and C++23: ```cpp #elif defined(MEOW) // -> #elifdef MEOW #elif !defined(MEOW) // -> #elifndef MEOW ```
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‎clang-tools-extra/clang-tidy/readability/CMakeLists.txt

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@@ -58,6 +58,7 @@ add_clang_library(clangTidyReadabilityModule STATIC
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UniqueptrDeleteReleaseCheck.cpp
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UppercaseLiteralSuffixCheck.cpp
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UseAnyOfAllOfCheck.cpp
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UseConcisePreprocessorDirectivesCheck.cpp
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UseStdMinMaxCheck.cpp
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LINK_LIBS

‎clang-tools-extra/clang-tidy/readability/ReadabilityTidyModule.cpp

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@@ -61,6 +61,7 @@
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#include "UniqueptrDeleteReleaseCheck.h"
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#include "UppercaseLiteralSuffixCheck.h"
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#include "UseAnyOfAllOfCheck.h"
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#include "UseConcisePreprocessorDirectivesCheck.h"
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#include "UseStdMinMaxCheck.h"
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namespace clang::tidy {
@@ -173,6 +174,8 @@ class ReadabilityModule : public ClangTidyModule {
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"readability-uppercase-literal-suffix");
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CheckFactories.registerCheck<UseAnyOfAllOfCheck>(
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"readability-use-anyofallof");
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CheckFactories.registerCheck<UseConcisePreprocessorDirectivesCheck>(
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"readability-use-concise-preprocessor-directives");
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CheckFactories.registerCheck<UseStdMinMaxCheck>(
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"readability-use-std-min-max");
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}

‎clang-tools-extra/clang-tidy/readability/UseConcisePreprocessorDirectivesCheck.cpp

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//===--- UseConcisePreprocessorDirectivesCheck.cpp - clang-tidy -----------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "UseConcisePreprocessorDirectivesCheck.h"
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#include "clang/Basic/TokenKinds.h"
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#include "clang/Lex/Lexer.h"
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#include "clang/Lex/PPCallbacks.h"
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#include "clang/Lex/Preprocessor.h"
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#include <array>
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namespace clang::tidy::readability {
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namespace {
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class IfPreprocessorCallbacks final : public PPCallbacks {
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public:
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IfPreprocessorCallbacks(ClangTidyCheck &Check, const Preprocessor &PP)
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: Check(Check), PP(PP) {}
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void If(SourceLocation Loc, SourceRange ConditionRange,
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ConditionValueKind) override {
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impl(Loc, ConditionRange, {"ifdef", "ifndef"});
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}
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void Elif(SourceLocation Loc, SourceRange ConditionRange, ConditionValueKind,
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SourceLocation) override {
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if (PP.getLangOpts().C23 || PP.getLangOpts().CPlusPlus23)
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impl(Loc, ConditionRange, {"elifdef", "elifndef"});
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}
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private:
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void impl(SourceLocation DirectiveLoc, SourceRange ConditionRange,
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const std::array<llvm::StringLiteral, 2> &Replacements) {
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// Lexer requires its input range to be null-terminated.
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SmallString<128> Condition =
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Lexer::getSourceText(CharSourceRange::getTokenRange(ConditionRange),
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PP.getSourceManager(), PP.getLangOpts());
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Condition.push_back('\0');
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Lexer Lex(DirectiveLoc, PP.getLangOpts(), Condition.data(),
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Condition.data(), Condition.data() + Condition.size() - 1);
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Token Tok;
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bool Inverted = false; // The inverted form of #*def is #*ndef.
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std::size_t ParensNestingDepth = 0;
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for (;;) {
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if (Lex.LexFromRawLexer(Tok))
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return;
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if (Tok.is(tok::TokenKind::exclaim) ||
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(PP.getLangOpts().CPlusPlus &&
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Tok.is(tok::TokenKind::raw_identifier) &&
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Tok.getRawIdentifier() == "not"))
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Inverted = !Inverted;
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else if (Tok.is(tok::TokenKind::l_paren))
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++ParensNestingDepth;
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else
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break;
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}
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if (Tok.isNot(tok::TokenKind::raw_identifier) ||
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Tok.getRawIdentifier() != "defined")
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return;
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bool NoMoreTokens = Lex.LexFromRawLexer(Tok);
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if (Tok.is(tok::TokenKind::l_paren)) {
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if (NoMoreTokens)
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return;
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++ParensNestingDepth;
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NoMoreTokens = Lex.LexFromRawLexer(Tok);
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}
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if (Tok.isNot(tok::TokenKind::raw_identifier))
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return;
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const StringRef Macro = Tok.getRawIdentifier();
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while (!NoMoreTokens) {
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NoMoreTokens = Lex.LexFromRawLexer(Tok);
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if (Tok.isNot(tok::TokenKind::r_paren))
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return;
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--ParensNestingDepth;
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}
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if (ParensNestingDepth != 0)
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return;
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Check.diag(
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DirectiveLoc,
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"preprocessor condition can be written more concisely using '#%0'")
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<< FixItHint::CreateReplacement(DirectiveLoc, Replacements[Inverted])
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<< FixItHint::CreateReplacement(ConditionRange, Macro)
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<< Replacements[Inverted];
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}
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ClangTidyCheck &Check;
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const Preprocessor &PP;
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};
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} // namespace
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void UseConcisePreprocessorDirectivesCheck::registerPPCallbacks(
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const SourceManager &, Preprocessor *PP, Preprocessor *) {
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PP->addPPCallbacks(std::make_unique<IfPreprocessorCallbacks>(*this, *PP));
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}
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} // namespace clang::tidy::readability

‎clang-tools-extra/clang-tidy/readability/UseConcisePreprocessorDirectivesCheck.h

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//===--- UseConcisePreprocessorDirectivesCheck.h - clang-tidy ---*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USECONCISEPREPROCESSORDIRECTIVESCHECK_H
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#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USECONCISEPREPROCESSORDIRECTIVESCHECK_H
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#include "../ClangTidyCheck.h"
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namespace clang::tidy::readability {
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/// Finds uses of ``#if`` that can be simplified to ``#ifdef`` or ``#ifndef``
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/// and, since C23 and C++23, uses of ``#elif`` that can be simplified to
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/// ``#elifdef`` or ``#elifndef``.
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///
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/// User-facing documentation:
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/// https://clang.llvm.org/extra/clang-tidy/checks/readability/use-concise-preprocessor-directives.html
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class UseConcisePreprocessorDirectivesCheck : public ClangTidyCheck {
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public:
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using ClangTidyCheck::ClangTidyCheck;
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void registerPPCallbacks(const SourceManager &SM, Preprocessor *PP,
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Preprocessor *ModuleExpanderPP) override;
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bool isLanguageVersionSupported(const LangOptions &LangOpts) const override {
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return true;
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}
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};
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} // namespace clang::tidy::readability
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#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_READABILITY_USECONCISEPREPROCESSORDIRECTIVESCHECK_H

‎clang-tools-extra/docs/ReleaseNotes.rst

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@@ -166,6 +166,13 @@ New checks
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Finds potentially erroneous calls to ``reset`` method on smart pointers when
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the pointee type also has a ``reset`` method.
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- New :doc:`readability-use-concise-preprocessor-directives
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<clang-tidy/checks/readability/use-concise-preprocessor-directives>` check.
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Finds uses of ``#if`` that can be simplified to ``#ifdef`` or ``#ifndef`` and,
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since C23 and C++23, uses of ``#elif`` that can be simplified to ``#elifdef``
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or ``#elifndef``.
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New check aliases
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^^^^^^^^^^^^^^^^^
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‎clang-tools-extra/docs/clang-tidy/checks/list.rst

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@@ -411,6 +411,7 @@ Clang-Tidy Checks
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:doc:`readability-uniqueptr-delete-release <readability/uniqueptr-delete-release>`, "Yes"
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:doc:`readability-uppercase-literal-suffix <readability/uppercase-literal-suffix>`, "Yes"
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:doc:`readability-use-anyofallof <readability/use-anyofallof>`,
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:doc:`readability-use-concise-preprocessor-directives <readability/use-concise-preprocessor-directives>`, "Yes"
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:doc:`readability-use-std-min-max <readability/use-std-min-max>`, "Yes"
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:doc:`zircon-temporary-objects <zircon/temporary-objects>`,
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‎clang-tools-extra/docs/clang-tidy/checks/readability/use-concise-preprocessor-directives.rst

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.. title:: clang-tidy - readability-use-concise-preprocessor-directives
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readability-use-concise-preprocessor-directives
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===============================================
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Finds uses of ``#if`` that can be simplified to ``#ifdef`` or ``#ifndef`` and,
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since C23 and C++23, uses of ``#elif`` that can be simplified to ``#elifdef``
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or ``#elifndef``:
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.. code-block:: c++
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#if defined(MEOW)
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#if !defined(MEOW)
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// becomes
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#ifdef MEOW
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#ifndef MEOW
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Since C23 and C++23:
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.. code-block:: c++
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#elif defined(MEOW)
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#elif !defined(MEOW)
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// becomes
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#elifdef MEOW
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#elifndef MEOW

‎clang-tools-extra/test/clang-tidy/checkers/readability/use-concise-preprocessor-directives.cpp

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// RUN: %check_clang_tidy -std=c++98,c++11,c++14,c++17,c++20 -check-suffixes=,CXX %s readability-use-concise-preprocessor-directives %t
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// RUN: %check_clang_tidy -std=c++23-or-later -check-suffixes=,23,CXX,CXX23 %s readability-use-concise-preprocessor-directives %t
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// RUN: %check_clang_tidy -std=c99,c11,c17 %s readability-use-concise-preprocessor-directives %t -- -- -x c
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// RUN: %check_clang_tidy -std=c23-or-later -check-suffixes=,23 %s readability-use-concise-preprocessor-directives %t -- -- -x c
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifdef FOO
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#if defined(FOO)
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifdef BAR
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#elif defined(BAR)
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifdef FOO
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#if defined FOO
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifdef BAR
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#elif defined BAR
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifdef FOO
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#if (defined(FOO))
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// CHECK-MESSAGES-23: :[[@LINE+2]]:4: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: # elifdef BAR
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# elif (defined(BAR))
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifdef FOO
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#if (defined FOO)
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// CHECK-MESSAGES-23: :[[@LINE+2]]:4: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: # elifdef BAR
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# elif (defined BAR)
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !defined(FOO)
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifndef BAR
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#elif !defined(BAR)
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#endif
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#ifdef __cplusplus
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// CHECK-MESSAGES-CXX: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-CXX: #ifndef FOO
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#if not defined(FOO)
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// CHECK-MESSAGES-CXX23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-CXX23: #elifndef BAR
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#elif not defined(BAR)
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#endif
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#endif // __cplusplus
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !defined FOO
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifndef BAR
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#elif !defined BAR
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#endif
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#ifdef __cplusplus
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// CHECK-MESSAGES-CXX: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-CXX: #ifndef FOO
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#if not defined FOO
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// CHECK-MESSAGES-CXX23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-CXX23: #elifndef BAR
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#elif not defined BAR
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#endif
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#endif // __cplusplus
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if (!defined(FOO))
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifndef BAR
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#elif (!defined(BAR))
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if (!defined FOO)
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifndef BAR
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#elif (!defined BAR)
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !(defined(FOO))
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifndef BAR
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#elif !(defined(BAR))
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !(defined FOO)
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifndef BAR
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#elif !(defined BAR)
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#endif
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// These cases with many parentheses and negations are unrealistic, but
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// handling them doesn't really add any complexity to the implementation.
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// Test them for good measure.
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !((!!(defined(FOO))))
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifdef BAR
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#elif ((!(!(defined(BAR)))))
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !((!!(defined FOO)))
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifdef BAR
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#elif ((!(!(defined BAR))))
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#endif
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// CHECK-MESSAGES: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#ifndef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES: #ifndef FOO
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#if !( (!! ( defined FOO )) )
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// CHECK-MESSAGES-23: :[[@LINE+2]]:2: warning: preprocessor condition can be written more concisely using '#elifdef' [readability-use-concise-preprocessor-directives]
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// CHECK-FIXES-23: #elifdef BAR
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#elif ( ( !(!( defined BAR) ) ))
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#endif
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#if FOO
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#elif BAR
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#endif
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#if defined(FOO) && defined(BAR)
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#elif defined(FOO) && defined(BAR)
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#endif
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#if defined FOO && BAR
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#endif

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