Commit 2634bd59 authored by Roman Lebedev's avatar Roman Lebedev
Browse files

[clang-tidy] Avoid C arrays check 

Summary:
[[ https://bugs.llvm.org/show_bug.cgi?id=39224 | PR39224 ]]
As discussed, we can't always do the transform automatically due to that array-to-pointer decay of C array.
In order to detect whether we can do said transform, we'd need to be able to see all usages of said array,
which is, i would say, rather impossible if e.g. it is in the header.
Thus right now no fixit exists.

Exceptions: `extern "C"` code.

References:
* [[ https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#es27-use-stdarray-or-stack_array-for-arrays-on-the-stack | CPPCG ES.27: Use std::array or stack_array for arrays on the stack ]]
* [[ https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#slcon1-prefer-using-stl-array-or-vector-instead-of-a-c-array | CPPCG SL.con.1: Prefer using STL array or vector instead of a C array ]]
* HICPP `4.1.1 Ensure that a function argument does not undergo an array-to-pointer conversion`
* MISRA `5-2-12 An identifier with array type passed as a function argument shall not decay to a pointer`

Reviewers: aaron.ballman, JonasToth, alexfh, hokein, xazax.hun

Reviewed By: JonasToth

Subscribers: Eugene.Zelenko, mgorny, rnkovacs, cfe-commits

Tags: #clang-tools-extra

Differential Revision: https://reviews.llvm.org/D53771

llvm-svn: 346835
parent 789cc817

clang-tools-extra/clang-tidy/cppcoreguidelines/CMakeLists.txt

+1 −0
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ add_clang_library(clangTidyCppCoreGuidelinesModule 
  clangLex

  clangTidy

  clangTidyMiscModule

  clangTidyModernizeModule

  clangTidyReadabilityModule

  clangTidyUtils

  clangTooling

clang-tools-extra/clang-tidy/cppcoreguidelines/CppCoreGuidelinesTidyModule.cpp

+3 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include "../ClangTidyModuleRegistry.h"

#include "../misc/NonPrivateMemberVariablesInClassesCheck.h"

#include "../misc/UnconventionalAssignOperatorCheck.h"

#include "../modernize/AvoidCArraysCheck.h"

#include "../readability/MagicNumbersCheck.h"

#include "AvoidGotoCheck.h"

#include "InterfacesGlobalInitCheck.h"
@@ -40,6 +41,8 @@ namespace cppcoreguidelines { 
class CppCoreGuidelinesModule : public ClangTidyModule {

public:

  void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {

    CheckFactories.registerCheck<modernize::AvoidCArraysCheck>(

        "cppcoreguidelines-avoid-c-arrays");

    CheckFactories.registerCheck<AvoidGotoCheck>(

        "cppcoreguidelines-avoid-goto");

    CheckFactories.registerCheck<readability::MagicNumbersCheck>(

clang-tools-extra/clang-tidy/hicpp/HICPPTidyModule.cpp

+3 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#include "../misc/NewDeleteOverloadsCheck.h"

#include "../misc/StaticAssertCheck.h"

#include "../bugprone/UndelegatedConstructorCheck.h"

#include "../modernize/AvoidCArraysCheck.h"

#include "../modernize/DeprecatedHeadersCheck.h"

#include "../modernize/UseAutoCheck.h"

#include "../modernize/UseEmplaceCheck.h"
@@ -48,6 +49,8 @@ namespace hicpp { 
class HICPPModule : public ClangTidyModule {

public:

  void addCheckFactories(ClangTidyCheckFactories &CheckFactories) override {

    CheckFactories.registerCheck<modernize::AvoidCArraysCheck>(

        "hicpp-avoid-c-arrays");

    CheckFactories.registerCheck<cppcoreguidelines::AvoidGotoCheck>(

        "hicpp-avoid-goto");

    CheckFactories.registerCheck<readability::BracesAroundStatementsCheck>(

clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.cpp

0 → 100644
+69 −0
Original line number Diff line number Diff line 
//===--- AvoidCArraysCheck.cpp - clang-tidy -------------------------------===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//



#include "AvoidCArraysCheck.h"

#include "clang/AST/ASTContext.h"

#include "clang/ASTMatchers/ASTMatchFinder.h"



using namespace clang::ast_matchers;



namespace {



AST_MATCHER(clang::TypeLoc, hasValidBeginLoc) {

  return Node.getBeginLoc().isValid();

}



AST_MATCHER_P(clang::TypeLoc, hasType,

              clang::ast_matchers::internal::Matcher<clang::Type>,

              InnerMatcher) {

  const clang::Type *TypeNode = Node.getTypePtr();

  return TypeNode != nullptr &&

         InnerMatcher.matches(*TypeNode, Finder, Builder);

}



AST_MATCHER(clang::RecordDecl, isExternCContext) {

  return Node.isExternCContext();

}



} // namespace



namespace clang {

namespace tidy {

namespace modernize {



void AvoidCArraysCheck::registerMatchers(MatchFinder *Finder) {

  // std::array<> is avaliable since C++11.

  if (!getLangOpts().CPlusPlus11)

    return;



  Finder->addMatcher(

      typeLoc(hasValidBeginLoc(), hasType(arrayType()),

              unless(anyOf(hasParent(varDecl(isExternC())),

                           hasParent(fieldDecl(

                               hasParent(recordDecl(isExternCContext())))),

                           hasAncestor(functionDecl(isExternC())))))

          .bind("typeloc"),

      this);

}



void AvoidCArraysCheck::check(const MatchFinder::MatchResult &Result) {

  const auto *ArrayType = Result.Nodes.getNodeAs<TypeLoc>("typeloc");



  static constexpr llvm::StringLiteral UseArray = llvm::StringLiteral(

      "do not declare C-style arrays, use std::array<> instead");

  static constexpr llvm::StringLiteral UseVector = llvm::StringLiteral(

      "do not declare C VLA arrays, use std::vector<> instead");



  diag(ArrayType->getBeginLoc(),

       ArrayType->getTypePtr()->isVariableArrayType() ? UseVector : UseArray);

}



} // namespace modernize

} // namespace tidy

} // namespace clang

clang-tools-extra/clang-tidy/modernize/AvoidCArraysCheck.h

0 → 100644
+35 −0
Original line number Diff line number Diff line 
//===--- AvoidCArraysCheck.h - clang-tidy -----------------------*- C++ -*-===//

//

//                     The LLVM Compiler Infrastructure

//

// This file is distributed under the University of Illinois Open Source

// License. See LICENSE.TXT for details.

//

//===----------------------------------------------------------------------===//



#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_AVOIDCARRAYSCHECK_H

#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_AVOIDCARRAYSCHECK_H



#include "../ClangTidy.h"



namespace clang {

namespace tidy {

namespace modernize {



/// Find C-style array types and recommend to use std::array<> / std::vector<>.

///

/// For the user-facing documentation see:

/// http://clang.llvm.org/extra/clang-tidy/checks/modernize-avoid-c-arrays.html

class AvoidCArraysCheck : public ClangTidyCheck {

public:

  AvoidCArraysCheck(StringRef Name, ClangTidyContext *Context)

      : ClangTidyCheck(Name, Context) {}

  void registerMatchers(ast_matchers::MatchFinder *Finder) override;

  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;

};



} // namespace modernize

} // namespace tidy

} // namespace clang



#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_MODERNIZE_AVOIDCARRAYSCHECK_H