clang-tools-extra/clang-tidy/bugprone/BoolPointerImplicitConversionCheck.cpp

   1 //===--- BoolPointerImplicitConversionCheck.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 "BoolPointerImplicitConversionCheck.h"
  10
  11 using namespace clang::ast_matchers;
  12
  13 namespace clang::tidy::bugprone {
  14
  15 void BoolPointerImplicitConversionCheck::registerMatchers(MatchFinder *Finder) {
  16   // Look for ifs that have an implicit bool* to bool conversion in the
  17   // condition. Filter negations.
  18   Finder->addMatcher(
  19       traverse(
  20           TK_AsIs,
  21           ifStmt(
  22               hasCondition(findAll(implicitCastExpr(
  23                   unless(hasParent(unaryOperator(hasOperatorName("!")))),
  24                   hasSourceExpression(expr(
  25                       hasType(pointerType(pointee(booleanType()))),
  26                       ignoringParenImpCasts(anyOf(declRefExpr().bind("expr"),
  27                                                   memberExpr().bind("expr"))))),
  28                   hasCastKind(CK_PointerToBoolean)))),
  29               unless(isInTemplateInstantiation()))
  30               .bind("if")),
  31       this);
  32 }
  33
  34 static void checkImpl(const MatchFinder::MatchResult &Result, const Expr *Ref,
  35                       const IfStmt *If,
  36                       const ast_matchers::internal::Matcher<Expr> &RefMatcher,
  37                       ClangTidyCheck &Check) {
  38   // Ignore macros.
  39   if (Ref->getBeginLoc().isMacroID())
  40     return;
  41
  42   // Only allow variable accesses and member exprs for now, no function calls.
  43   // Check that we don't dereference the variable anywhere within the if. This
  44   // avoids false positives for checks of the pointer for nullptr before it is
  45   // dereferenced. If there is a dereferencing operator on this variable don't
  46   // emit a diagnostic. Also ignore array subscripts.
  47   if (!match(findAll(unaryOperator(hasOperatorName("*"),
  48                                    hasUnaryOperand(RefMatcher))),
  49              *If, *Result.Context)
  50            .empty() ||
  51       !match(findAll(arraySubscriptExpr(hasBase(RefMatcher))), *If,
  52              *Result.Context)
  53            .empty() ||
  54       // FIXME: We should still warn if the paremater is implicitly converted to
  55       // bool.
  56       !match(
  57            findAll(callExpr(hasAnyArgument(ignoringParenImpCasts(RefMatcher)))),
  58            *If, *Result.Context)
  59            .empty() ||
  60       !match(
  61            findAll(cxxDeleteExpr(has(ignoringParenImpCasts(expr(RefMatcher))))),
  62            *If, *Result.Context)
  63            .empty())
  64     return;
  65
  66   Check.diag(Ref->getBeginLoc(),
  67              "dubious check of 'bool *' against 'nullptr', did "
  68              "you mean to dereference it?")
  69       << FixItHint::CreateInsertion(Ref->getBeginLoc(), "*");
  70 }
  71
  72 void BoolPointerImplicitConversionCheck::check(
  73     const MatchFinder::MatchResult &Result) {
  74   const auto *If = Result.Nodes.getNodeAs<IfStmt>("if");
  75   if (const auto *E = Result.Nodes.getNodeAs<Expr>("expr")) {
  76     const Decl *D = isa<DeclRefExpr>(E) ? cast<DeclRefExpr>(E)->getDecl()
  77                                         : cast<MemberExpr>(E)->getMemberDecl();
  78     const auto M =
  79         ignoringParenImpCasts(anyOf(declRefExpr(to(equalsNode(D))),
  80                                     memberExpr(hasDeclaration(equalsNode(D)))));
  81     checkImpl(Result, E, If, M, *this);
  82   }
  83 }
  84
  85 } // namespace clang::tidy::bugprone