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

   1 //===--- AvoidCArraysCheck.cpp - clang-tidy -------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "AvoidCArraysCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/ASTMatchers/ASTMatchFinder.h"
  12 #include "clang/ASTMatchers/ASTMatchers.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::modernize {
  17
  18 namespace {
  19
  20 AST_MATCHER(clang::TypeLoc, hasValidBeginLoc) {
  21   return Node.getBeginLoc().isValid();
  22 }
  23
  24 AST_MATCHER_P(clang::TypeLoc, hasType,
  25               clang::ast_matchers::internal::Matcher<clang::Type>,
  26               InnerMatcher) {
  27   const clang::Type *TypeNode = Node.getTypePtr();
  28   return TypeNode != nullptr &&
  29          InnerMatcher.matches(*TypeNode, Finder, Builder);
  30 }
  31
  32 AST_MATCHER(clang::RecordDecl, isExternCContext) {
  33   return Node.isExternCContext();
  34 }
  35
  36 AST_MATCHER(clang::ParmVarDecl, isArgvOfMain) {
  37   const clang::DeclContext *DC = Node.getDeclContext();
  38   const auto *FD = llvm::dyn_cast<clang::FunctionDecl>(DC);
  39   return FD ? FD->isMain() : false;
  40 }
  41
  42 } // namespace
  43
  44 AvoidCArraysCheck::AvoidCArraysCheck(StringRef Name, ClangTidyContext *Context)
  45     : ClangTidyCheck(Name, Context),
  46       AllowStringArrays(Options.get("AllowStringArrays", false)) {}
  47
  48 void AvoidCArraysCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
  49   Options.store(Opts, "AllowStringArrays", AllowStringArrays);
  50 }
  51
  52 void AvoidCArraysCheck::registerMatchers(MatchFinder *Finder) {
  53   ast_matchers::internal::Matcher<TypeLoc> IgnoreStringArrayIfNeededMatcher =
  54       anything();
  55   if (AllowStringArrays)
  56     IgnoreStringArrayIfNeededMatcher =
  57         unless(typeLoc(loc(hasCanonicalType(incompleteArrayType(
  58                            hasElementType(isAnyCharacter())))),
  59                        hasParent(varDecl(hasInitializer(stringLiteral()),
  60                                          unless(parmVarDecl())))));
  61
  62   Finder->addMatcher(
  63       typeLoc(hasValidBeginLoc(), hasType(arrayType()),
  64               optionally(hasParent(parmVarDecl().bind("param_decl"))),
  65               unless(anyOf(hasParent(parmVarDecl(isArgvOfMain())),
  66                            hasParent(varDecl(isExternC())),
  67                            hasParent(fieldDecl(
  68                                hasParent(recordDecl(isExternCContext())))),
  69                            hasAncestor(functionDecl(isExternC())))),
  70               std::move(IgnoreStringArrayIfNeededMatcher))
  71           .bind("typeloc"),
  72       this);
  73 }
  74
  75 void AvoidCArraysCheck::check(const MatchFinder::MatchResult &Result) {
  76   const auto *ArrayType = Result.Nodes.getNodeAs<TypeLoc>("typeloc");
  77   const bool IsInParam =
  78       Result.Nodes.getNodeAs<ParmVarDecl>("param_decl") != nullptr;
  79   const bool IsVLA = ArrayType->getTypePtr()->isVariableArrayType();
  80   enum class RecommendType { Array, Vector, Span };
  81   llvm::SmallVector<const char *> RecommendTypes{};
  82   if (IsVLA) {
  83     RecommendTypes.push_back("'std::vector'");
  84   } else if (ArrayType->getTypePtr()->isIncompleteArrayType() && IsInParam) {
  85     // in function parameter, we also don't know the size of
  86     // IncompleteArrayType.
  87     if (Result.Context->getLangOpts().CPlusPlus20)
  88       RecommendTypes.push_back("'std::span'");
  89     else {
  90       RecommendTypes.push_back("'std::array'");
  91       RecommendTypes.push_back("'std::vector'");
  92     }
  93   } else {
  94     RecommendTypes.push_back("'std::array'");
  95   }
  96   diag(ArrayType->getBeginLoc(),
  97        "do not declare %select{C-style|C VLA}0 arrays, use %1 instead")
  98       << IsVLA << llvm::join(RecommendTypes, " or ");
  99 }
 100
 101 } // namespace clang::tidy::modernize