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

   1 //===--- AssignmentInIfConditionCheck.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 "AssignmentInIfConditionCheck.h"
  10 #include "clang/AST/ASTContext.h"
  11 #include "clang/AST/RecursiveASTVisitor.h"
  12 #include "clang/ASTMatchers/ASTMatchFinder.h"
  13
  14 using namespace clang::ast_matchers;
  15
  16 namespace clang::tidy::bugprone {
  17
  18 void AssignmentInIfConditionCheck::registerMatchers(MatchFinder *Finder) {
  19   Finder->addMatcher(translationUnitDecl(), this);
  20 }
  21
  22 void AssignmentInIfConditionCheck::check(
  23     const ast_matchers::MatchFinder::MatchResult &Result) {
  24   class Visitor : public RecursiveASTVisitor<Visitor> {
  25     AssignmentInIfConditionCheck &Check;
  26
  27   public:
  28     explicit Visitor(AssignmentInIfConditionCheck &Check) : Check(Check) {}
  29     bool VisitIfStmt(IfStmt *If) {
  30       class ConditionVisitor : public RecursiveASTVisitor<ConditionVisitor> {
  31         AssignmentInIfConditionCheck &Check;
  32
  33       public:
  34         explicit ConditionVisitor(AssignmentInIfConditionCheck &Check)
  35             : Check(Check) {}
  36
  37         // Dont traverse into any lambda expressions.
  38         bool TraverseLambdaExpr(LambdaExpr *, DataRecursionQueue * = nullptr) {
  39           return true;
  40         }
  41
  42         bool VisitBinaryOperator(BinaryOperator *BO) {
  43           if (BO->isAssignmentOp())
  44             Check.report(BO);
  45           return true;
  46         }
  47
  48         bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr *OCE) {
  49           if (OCE->isAssignmentOp())
  50             Check.report(OCE);
  51           return true;
  52         }
  53       };
  54
  55       ConditionVisitor(Check).TraverseStmt(If->getCond());
  56       return true;
  57     }
  58   };
  59   Visitor(*this).TraverseAST(*Result.Context);
  60 }
  61
  62 void AssignmentInIfConditionCheck::report(const Expr *AssignmentExpr) {
  63   SourceLocation OpLoc =
  64       isa<BinaryOperator>(AssignmentExpr)
  65           ? cast<BinaryOperator>(AssignmentExpr)->getOperatorLoc()
  66           : cast<CXXOperatorCallExpr>(AssignmentExpr)->getOperatorLoc();
  67
  68   diag(OpLoc, "an assignment within an 'if' condition is bug-prone")
  69       << AssignmentExpr->getSourceRange();
  70   diag(OpLoc,
  71        "if it should be an assignment, move it out of the 'if' condition",
  72        DiagnosticIDs::Note);
  73   diag(OpLoc, "if it is meant to be an equality check, change '=' to '=='",
  74        DiagnosticIDs::Note);
  75 }
  76
  77 } // namespace clang::tidy::bugprone