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

   1 //===--- AssertSideEffectCheck.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 "AssertSideEffectCheck.h"
  10 #include "../utils/Matchers.h"
  11 #include "../utils/OptionsUtils.h"
  12 #include "clang/AST/ASTContext.h"
  13 #include "clang/ASTMatchers/ASTMatchFinder.h"
  14 #include "clang/Frontend/CompilerInstance.h"
  15 #include "clang/Lex/Lexer.h"
  16 #include "llvm/ADT/SmallVector.h"
  17 #include "llvm/ADT/StringRef.h"
  18 #include "llvm/Support/Casting.h"
  19 #include <algorithm>
  20 #include <string>
  21
  22 using namespace clang::ast_matchers;
  23
  24 namespace clang::tidy::bugprone {
  25
  26 namespace {
  27
  28 AST_MATCHER_P2(Expr, hasSideEffect, bool, CheckFunctionCalls,
  29                clang::ast_matchers::internal::Matcher<NamedDecl>,
  30                IgnoredFunctionsMatcher) {
  31   const Expr *E = &Node;
  32
  33   if (const auto *Op = dyn_cast<UnaryOperator>(E)) {
  34     UnaryOperator::Opcode OC = Op->getOpcode();
  35     return OC == UO_PostInc || OC == UO_PostDec || OC == UO_PreInc ||
  36            OC == UO_PreDec;
  37   }
  38
  39   if (const auto *Op = dyn_cast<BinaryOperator>(E)) {
  40     return Op->isAssignmentOp();
  41   }
  42
  43   if (const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E)) {
  44     if (const auto *MethodDecl =
  45             dyn_cast_or_null<CXXMethodDecl>(OpCallExpr->getDirectCallee()))
  46       if (MethodDecl->isConst())
  47         return false;
  48
  49     OverloadedOperatorKind OpKind = OpCallExpr->getOperator();
  50     return OpKind == OO_Equal || OpKind == OO_PlusEqual ||
  51            OpKind == OO_MinusEqual || OpKind == OO_StarEqual ||
  52            OpKind == OO_SlashEqual || OpKind == OO_AmpEqual ||
  53            OpKind == OO_PipeEqual || OpKind == OO_CaretEqual ||
  54            OpKind == OO_LessLessEqual || OpKind == OO_GreaterGreaterEqual ||
  55            OpKind == OO_LessLess || OpKind == OO_GreaterGreater ||
  56            OpKind == OO_PlusPlus || OpKind == OO_MinusMinus ||
  57            OpKind == OO_PercentEqual || OpKind == OO_New ||
  58            OpKind == OO_Delete || OpKind == OO_Array_New ||
  59            OpKind == OO_Array_Delete;
  60   }
  61
  62   if (const auto *CExpr = dyn_cast<CallExpr>(E)) {
  63     if (!CheckFunctionCalls)
  64       return false;
  65     if (const auto *FuncDecl = CExpr->getDirectCallee()) {
  66       if (FuncDecl->getDeclName().isIdentifier() &&
  67           IgnoredFunctionsMatcher.matches(*FuncDecl, Finder,
  68                                           Builder)) // exceptions come here
  69         return false;
  70       for (size_t I = 0; I < FuncDecl->getNumParams(); I++) {
  71         const ParmVarDecl *P = FuncDecl->getParamDecl(I);
  72         const Expr *ArgExpr =
  73             I < CExpr->getNumArgs() ? CExpr->getArg(I) : nullptr;
  74         const QualType PT = P->getType().getCanonicalType();
  75         if (ArgExpr && !ArgExpr->isXValue() && PT->isReferenceType() &&
  76             !PT.getNonReferenceType().isConstQualified())
  77           return true;
  78       }
  79       if (const auto *MethodDecl = dyn_cast<CXXMethodDecl>(FuncDecl))
  80         return !MethodDecl->isConst();
  81     }
  82     return true;
  83   }
  84
  85   return isa<CXXNewExpr>(E) || isa<CXXDeleteExpr>(E) || isa<CXXThrowExpr>(E);
  86 }
  87
  88 } // namespace
  89
  90 AssertSideEffectCheck::AssertSideEffectCheck(StringRef Name,
  91                                              ClangTidyContext *Context)
  92     : ClangTidyCheck(Name, Context),
  93       CheckFunctionCalls(Options.get("CheckFunctionCalls", false)),
  94       RawAssertList(Options.get("AssertMacros", "assert,NSAssert,NSCAssert")),
  95       IgnoredFunctions(utils::options::parseListPair(
  96           "__builtin_expect;", Options.get("IgnoredFunctions", ""))) {
  97   StringRef(RawAssertList).split(AssertMacros, ",", -1, false);
  98 }
  99
 100 // The options are explained in AssertSideEffectCheck.h.
 101 void AssertSideEffectCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
 102   Options.store(Opts, "CheckFunctionCalls", CheckFunctionCalls);
 103   Options.store(Opts, "AssertMacros", RawAssertList);
 104   Options.store(Opts, "IgnoredFunctions",
 105                 utils::options::serializeStringList(IgnoredFunctions));
 106 }
 107
 108 void AssertSideEffectCheck::registerMatchers(MatchFinder *Finder) {
 109   auto IgnoredFunctionsMatcher =
 110       matchers::matchesAnyListedName(IgnoredFunctions);
 111
 112   auto DescendantWithSideEffect =
 113       traverse(TK_AsIs, hasDescendant(expr(hasSideEffect(
 114                             CheckFunctionCalls, IgnoredFunctionsMatcher))));
 115   auto ConditionWithSideEffect = hasCondition(DescendantWithSideEffect);
 116   Finder->addMatcher(
 117       stmt(
 118           anyOf(conditionalOperator(ConditionWithSideEffect),
 119                 ifStmt(ConditionWithSideEffect),
 120                 unaryOperator(hasOperatorName("!"),
 121                               hasUnaryOperand(unaryOperator(
 122                                   hasOperatorName("!"),
 123                                   hasUnaryOperand(DescendantWithSideEffect))))))
 124           .bind("condStmt"),
 125       this);
 126 }
 127
 128 void AssertSideEffectCheck::check(const MatchFinder::MatchResult &Result) {
 129   const SourceManager &SM = *Result.SourceManager;
 130   const LangOptions LangOpts = getLangOpts();
 131   SourceLocation Loc = Result.Nodes.getNodeAs<Stmt>("condStmt")->getBeginLoc();
 132
 133   StringRef AssertMacroName;
 134   while (Loc.isValid() && Loc.isMacroID()) {
 135     StringRef MacroName = Lexer::getImmediateMacroName(Loc, SM, LangOpts);
 136     Loc = SM.getImmediateMacroCallerLoc(Loc);
 137
 138     // Check if this macro is an assert.
 139     if (llvm::is_contained(AssertMacros, MacroName)) {
 140       AssertMacroName = MacroName;
 141       break;
 142     }
 143   }
 144   if (AssertMacroName.empty())
 145     return;
 146
 147   diag(Loc, "side effect in %0() condition discarded in release builds")
 148       << AssertMacroName;
 149 }
 150
 151 } // namespace clang::tidy::bugprone