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

   1 //===--- AvoidNonConstGlobalVariablesCheck.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 "AvoidNonConstGlobalVariablesCheck.h"
  10 #include "clang/ASTMatchers/ASTMatchFinder.h"
  11 #include "clang/ASTMatchers/ASTMatchers.h"
  12
  13 using namespace clang::ast_matchers;
  14
  15 namespace clang::tidy::cppcoreguidelines {
  16
  17 AvoidNonConstGlobalVariablesCheck::AvoidNonConstGlobalVariablesCheck(
  18     StringRef Name, ClangTidyContext *Context)
  19     : ClangTidyCheck(Name, Context),
  20       AllowInternalLinkage(Options.get("AllowInternalLinkage", false)) {}
  21
  22 void AvoidNonConstGlobalVariablesCheck::registerMatchers(MatchFinder *Finder) {
  23   auto NamespaceMatcher = AllowInternalLinkage
  24                               ? namespaceDecl(unless(isAnonymous()))
  25                               : namespaceDecl();
  26   auto GlobalContext =
  27       varDecl(hasGlobalStorage(),
  28               hasDeclContext(anyOf(NamespaceMatcher, translationUnitDecl())));
  29
  30   auto GlobalVariable = varDecl(
  31       GlobalContext,
  32       AllowInternalLinkage ? varDecl(unless(isStaticStorageClass()))
  33                            : varDecl(),
  34       unless(anyOf(
  35           isConstexpr(), hasType(isConstQualified()),
  36           hasType(referenceType())))); // References can't be changed, only the
  37                                        // data they reference can be changed.
  38
  39   auto GlobalReferenceToNonConst =
  40       varDecl(GlobalContext, hasType(referenceType()),
  41               unless(hasType(references(qualType(isConstQualified())))));
  42
  43   auto GlobalPointerToNonConst = varDecl(
  44       GlobalContext, hasType(pointerType(pointee(unless(isConstQualified())))));
  45
  46   Finder->addMatcher(GlobalVariable.bind("non-const_variable"), this);
  47   Finder->addMatcher(GlobalReferenceToNonConst.bind("indirection_to_non-const"),
  48                      this);
  49   Finder->addMatcher(GlobalPointerToNonConst.bind("indirection_to_non-const"),
  50                      this);
  51 }
  52
  53 void AvoidNonConstGlobalVariablesCheck::check(
  54     const MatchFinder::MatchResult &Result) {
  55   if (const auto *Variable =
  56           Result.Nodes.getNodeAs<VarDecl>("non-const_variable")) {
  57     diag(Variable->getLocation(), "variable %0 is non-const and globally "
  58                                   "accessible, consider making it const")
  59         << Variable; // FIXME: Add fix-it hint to Variable
  60     // Don't return early, a non-const variable may also be a pointer or
  61     // reference to non-const data.
  62   }
  63
  64   if (const auto *VD =
  65           Result.Nodes.getNodeAs<VarDecl>("indirection_to_non-const")) {
  66     diag(VD->getLocation(),
  67          "variable %0 provides global access to a non-const object; consider "
  68          "making the %select{referenced|pointed-to}1 data 'const'")
  69         << VD
  70         << VD->getType()->isPointerType(); // FIXME: Add fix-it hint to Variable
  71   }
  72 }
  73
  74 void AvoidNonConstGlobalVariablesCheck::storeOptions(
  75     ClangTidyOptions::OptionMap &Opts) {
  76   Options.store(Opts, "AllowInternalLinkage", AllowInternalLinkage);
  77 }
  78
  79 } // namespace clang::tidy::cppcoreguidelines