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 #include "plugin.hxx"
  16
  17 /**
  18 the comma operator is best used sparingly
  19 */
  20
  21 namespace {
  22
  23 Stmt const * lookThroughExprWithCleanups(Stmt const * stmt) {
  24     if (auto const e = dyn_cast_or_null<ExprWithCleanups>(stmt)) {
  25         return e->getSubExpr();
  26     }
  27     return stmt;
  28 }
  29
  30 class CommaOperator:
  31     public RecursiveASTVisitor<CommaOperator>, public loplugin::Plugin
  32 {
  33 public:
  34     explicit CommaOperator(loplugin::InstantiationData const & data):
  35         Plugin(data) {}
  36
  37     virtual void run() override
  38     {
  39         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  40     }
  41
  42     bool TraverseForStmt(ForStmt * stmt) {
  43         auto const saved1 = ignore1_;
  44         ignore1_ = lookThroughExprWithCleanups(stmt->getInit());
  45         auto const saved2 = ignore2_;
  46         ignore2_ = lookThroughExprWithCleanups(stmt->getInc());
  47         auto const ret = RecursiveASTVisitor::TraverseForStmt(stmt);
  48         ignore1_ = saved1;
  49         ignore2_ = saved2;
  50         return ret;
  51     }
  52
  53     bool TraverseWhileStmt(WhileStmt * stmt) {
  54         auto const saved1 = ignore1_;
  55         ignore1_ = lookThroughExprWithCleanups(stmt->getCond());
  56         auto const ret = RecursiveASTVisitor::TraverseWhileStmt(stmt);
  57         ignore1_ = saved1;
  58         return ret;
  59     }
  60
  61     bool TraverseParenExpr(ParenExpr * expr) {
  62         auto const saved1 = ignore1_;
  63         ignore1_ = expr->getSubExpr();
  64         auto const ret = RecursiveASTVisitor::TraverseParenExpr(expr);
  65         ignore1_ = saved1;
  66         return ret;
  67     }
  68
  69     bool TraverseBinComma(BinaryOperator * expr) {
  70         if (!WalkUpFromBinComma(expr)) {
  71             return false;
  72         }
  73         auto const saved1 = ignore1_;
  74         ignore1_ = expr->getLHS();
  75         auto const ret = TraverseStmt(expr->getLHS())
  76             && TraverseStmt(expr->getRHS());
  77         ignore1_ = saved1;
  78         return ret;
  79     }
  80
  81     bool VisitBinComma(const BinaryOperator* );
  82
  83 private:
  84     Stmt const * ignore1_ = nullptr;
  85     Stmt const * ignore2_ = nullptr;
  86 };
  87
  88 bool CommaOperator::VisitBinComma(const BinaryOperator* binaryOp)
  89 {
  90     if (binaryOp == ignore1_ || binaryOp == ignore2_) {
  91         return true;
  92     }
  93     if (ignoreLocation(binaryOp)) {
  94         return true;
  95     }
  96     // Ignore FD_SET expanding to "...} while(0, 0)" in some Microsoft
  97     // winsock2.h (TODO: improve heuristic of determining that the whole
  98     // binaryOp is part of a single macro body expansion):
  99     if (compiler.getSourceManager().isMacroBodyExpansion(
 100             binaryOp->getLocStart())
 101         && compiler.getSourceManager().isMacroBodyExpansion(
 102             binaryOp->getOperatorLoc())
 103         && compiler.getSourceManager().isMacroBodyExpansion(
 104             binaryOp->getLocEnd())
 105         && ignoreLocation(
 106             compiler.getSourceManager().getSpellingLoc(
 107                 binaryOp->getOperatorLoc())))
 108     {
 109         return true;
 110     }
 111     report(
 112         DiagnosticsEngine::Warning, "comma operator hides code",
 113         binaryOp->getOperatorLoc())
 114       << binaryOp->getSourceRange();
 115     return true;
 116 }
 117
 118
 119 loplugin::Plugin::Registration< CommaOperator > X("commaoperator", true);
 120
 121 }
 122
 123 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */