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