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/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::cppcoreguidelines {
  17
  18 void AvoidNonConstGlobalVariablesCheck::registerMatchers(MatchFinder *Finder) {
  19   auto GlobalContext =
  20       varDecl(hasGlobalStorage(),
  21               hasDeclContext(anyOf(namespaceDecl(), translationUnitDecl())));
  22
  23   auto GlobalVariable = varDecl(
  24       GlobalContext,
  25       unless(anyOf(
  26           isConstexpr(), hasType(isConstQualified()),
  27           hasType(referenceType())))); // References can't be changed, only the
  28                                        // data they reference can be changed.
  29
  30   auto GlobalReferenceToNonConst =
  31       varDecl(GlobalContext, hasType(referenceType()),
  32               unless(hasType(references(qualType(isConstQualified())))));
  33
  34   auto GlobalPointerToNonConst = varDecl(
  35       GlobalContext, hasType(pointerType(pointee(unless(isConstQualified())))));
  36
  37   Finder->addMatcher(GlobalVariable.bind("non-const_variable"), this);
  38   Finder->addMatcher(GlobalReferenceToNonConst.bind("indirection_to_non-const"),
  39                      this);
  40   Finder->addMatcher(GlobalPointerToNonConst.bind("indirection_to_non-const"),
  41                      this);
  42 }
  43
  44 void AvoidNonConstGlobalVariablesCheck::check(
  45     const MatchFinder::MatchResult &Result) {
  46
  47   if (const auto *Variable =
  48           Result.Nodes.getNodeAs<VarDecl>("non-const_variable")) {
  49     diag(Variable->getLocation(), "variable %0 is non-const and globally "
  50                                   "accessible, consider making it const")
  51         << Variable; // FIXME: Add fix-it hint to Variable
  52     // Don't return early, a non-const variable may also be a pointer or
  53     // reference to non-const data.
  54   }
  55
  56   if (const auto *VD =
  57           Result.Nodes.getNodeAs<VarDecl>("indirection_to_non-const")) {
  58     diag(VD->getLocation(),
  59          "variable %0 provides global access to a non-const object; consider "
  60          "making the %select{referenced|pointed-to}1 data 'const'")
  61         << VD
  62         << VD->getType()->isPointerType(); // FIXME: Add fix-it hint to Variable
  63   }
  64 }
  65
  66 } // namespace clang::tidy::cppcoreguidelines