compilerplugins/clang/commaoperator.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  */
   9
  10 #include <cassert>
  11 #include <string>
  12 #include <iostream>
  13 #include <fstream>
  14 #include <set>
  15
  16 #include "plugin.hxx"
  17
  18 /**
  19 the comma operator is best used sparingly
  20 */
  21
  22 namespace {
  23
  24 Stmt const * lookThroughExprWithCleanups(Stmt const * stmt) {
  25     if (auto const e = dyn_cast_or_null<ExprWithCleanups>(stmt)) {
  26         return e->getSubExpr();
  27     }
  28     return stmt;
  29 }
  30
  31 class CommaOperator:
  32     public loplugin::FilteringPlugin<CommaOperator>
  33 {
  34 public:
  35     explicit CommaOperator(loplugin::InstantiationData const & data):
  36         FilteringPlugin(data) {}
  37
  38     virtual void run() override
  39     {
  40         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  41     }
  42
  43     bool TraverseForStmt(ForStmt * stmt) {
  44         auto const saved1 = ignore1_;
  45         ignore1_ = lookThroughExprWithCleanups(stmt->getInit());
  46         auto const saved2 = ignore2_;
  47         ignore2_ = lookThroughExprWithCleanups(stmt->getInc());
  48         auto const ret = RecursiveASTVisitor::TraverseForStmt(stmt);
  49         ignore1_ = saved1;
  50         ignore2_ = saved2;
  51         return ret;
  52     }
  53
  54     bool TraverseWhileStmt(WhileStmt * stmt) {
  55         auto const saved1 = ignore1_;
  56         ignore1_ = lookThroughExprWithCleanups(stmt->getCond());
  57         auto const ret = RecursiveASTVisitor::TraverseWhileStmt(stmt);
  58         ignore1_ = saved1;
  59         return ret;
  60     }
  61
  62     bool TraverseParenExpr(ParenExpr * expr) {
  63         auto const saved1 = ignore1_;
  64         ignore1_ = expr->getSubExpr();
  65         auto const ret = RecursiveASTVisitor::TraverseParenExpr(expr);
  66         ignore1_ = saved1;
  67         return ret;
  68     }
  69
  70     bool TraverseBinaryOperator(BinaryOperator * expr) {
  71         if (expr->getOpcode() != BO_Comma) {
  72             return RecursiveASTVisitor::TraverseBinaryOperator(expr);
  73         }
  74         if (!WalkUpFromBinaryOperator(expr)) {
  75             return false;
  76         }
  77         auto const saved1 = ignore1_;
  78         ignore1_ = expr->getLHS();
  79         auto const ret = TraverseStmt(expr->getLHS())
  80             && TraverseStmt(expr->getRHS());
  81         ignore1_ = saved1;
  82         return ret;
  83     }
  84
  85     bool VisitBinaryOperator(const BinaryOperator* );
  86
  87 private:
  88     Stmt const * ignore1_ = nullptr;
  89     Stmt const * ignore2_ = nullptr;
  90 };
  91
  92 bool CommaOperator::VisitBinaryOperator(const BinaryOperator* binaryOp)
  93 {
  94     if (binaryOp->getOpcode() != BO_Comma) {
  95         return true;
  96     }
  97     if (binaryOp == ignore1_ || binaryOp == ignore2_) {
  98         return true;
  99     }
 100     if (ignoreLocation(binaryOp)) {
 101         return true;
 102     }
 103     // Ignore FD_SET expanding to "...} while(0, 0)" in some Microsoft
 104     // winsock2.h (TODO: improve heuristic of determining that the whole
 105     // binaryOp is part of a single macro body expansion):
 106     if (compiler.getSourceManager().isMacroBodyExpansion(
 107             binaryOp->getBeginLoc())
 108         && compiler.getSourceManager().isMacroBodyExpansion(
 109             binaryOp->getOperatorLoc())
 110         && compiler.getSourceManager().isMacroBodyExpansion(
 111             binaryOp->getEndLoc())
 112         && ignoreLocation(
 113             compiler.getSourceManager().getSpellingLoc(
 114                 binaryOp->getOperatorLoc())))
 115     {
 116         return true;
 117     }
 118     report(
 119         DiagnosticsEngine::Warning, "comma operator hides code",
 120         binaryOp->getOperatorLoc())
 121       << binaryOp->getSourceRange();
 122     return true;
 123 }
 124
 125
 126 loplugin::Plugin::Registration< CommaOperator > X("commaoperator", true);
 127
 128 }
 129
 130 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */