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 "config_clang.h"
  17
  18 #include "plugin.hxx"
  19
  20 /**
  21 the comma operator is best used sparingly
  22 */
  23
  24 namespace {
  25
  26 Stmt const * lookThroughExprWithCleanups(Stmt const * stmt) {
  27     if (auto const e = dyn_cast_or_null<ExprWithCleanups>(stmt)) {
  28         return e->getSubExpr();
  29     }
  30     return stmt;
  31 }
  32
  33 class CommaOperator:
  34     public loplugin::FilteringPlugin<CommaOperator>
  35 {
  36 public:
  37     explicit CommaOperator(loplugin::InstantiationData const & data):
  38         FilteringPlugin(data) {}
  39
  40     virtual void run() override
  41     {
  42         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  43     }
  44
  45     bool TraverseForStmt(ForStmt * stmt) {
  46         auto const saved1 = ignore1_;
  47         ignore1_ = lookThroughExprWithCleanups(stmt->getInit());
  48         auto const saved2 = ignore2_;
  49         ignore2_ = lookThroughExprWithCleanups(stmt->getInc());
  50         auto const ret = RecursiveASTVisitor::TraverseForStmt(stmt);
  51         ignore1_ = saved1;
  52         ignore2_ = saved2;
  53         return ret;
  54     }
  55
  56     bool TraverseWhileStmt(WhileStmt * stmt) {
  57         auto const saved1 = ignore1_;
  58         ignore1_ = lookThroughExprWithCleanups(stmt->getCond());
  59         auto const ret = RecursiveASTVisitor::TraverseWhileStmt(stmt);
  60         ignore1_ = saved1;
  61         return ret;
  62     }
  63
  64     bool TraverseParenExpr(ParenExpr * expr) {
  65         auto const saved1 = ignore1_;
  66         ignore1_ = expr->getSubExpr();
  67         auto const ret = RecursiveASTVisitor::TraverseParenExpr(expr);
  68         ignore1_ = saved1;
  69         return ret;
  70     }
  71
  72     bool TraverseBinaryOperator(BinaryOperator * expr) {
  73         if (expr->getOpcode() != BO_Comma) {
  74             return RecursiveASTVisitor::TraverseBinaryOperator(expr);
  75         }
  76         if (!WalkUpFromBinaryOperator(expr)) {
  77             return false;
  78         }
  79         auto const saved1 = ignore1_;
  80         ignore1_ = expr->getLHS();
  81         auto const ret = TraverseStmt(expr->getLHS())
  82             && TraverseStmt(expr->getRHS());
  83         ignore1_ = saved1;
  84         return ret;
  85     }
  86
  87 #if CLANG_VERSION < 110000
  88     bool TraverseBinComma(BinaryOperator * expr) { return TraverseBinaryOperator(expr); }
  89 #endif
  90
  91     bool VisitBinaryOperator(const BinaryOperator* );
  92
  93 private:
  94     Stmt const * ignore1_ = nullptr;
  95     Stmt const * ignore2_ = nullptr;
  96 };
  97
  98 bool CommaOperator::VisitBinaryOperator(const BinaryOperator* binaryOp)
  99 {
 100     if (binaryOp->getOpcode() != BO_Comma) {
 101         return true;
 102     }
 103     if (binaryOp == ignore1_ || binaryOp == ignore2_) {
 104         return true;
 105     }
 106     if (ignoreLocation(binaryOp)) {
 107         return true;
 108     }
 109     // Ignore FD_SET expanding to "...} while(0, 0)" in some Microsoft
 110     // winsock2.h (TODO: improve heuristic of determining that the whole
 111     // binaryOp is part of a single macro body expansion):
 112     if (compiler.getSourceManager().isMacroBodyExpansion(
 113             compat::getBeginLoc(binaryOp))
 114         && compiler.getSourceManager().isMacroBodyExpansion(
 115             binaryOp->getOperatorLoc())
 116         && compiler.getSourceManager().isMacroBodyExpansion(
 117             compat::getEndLoc(binaryOp))
 118         && ignoreLocation(
 119             compiler.getSourceManager().getSpellingLoc(
 120                 binaryOp->getOperatorLoc())))
 121     {
 122         return true;
 123     }
 124     report(
 125         DiagnosticsEngine::Warning, "comma operator hides code",
 126         binaryOp->getOperatorLoc())
 127       << binaryOp->getSourceRange();
 128     return true;
 129 }
 130
 131
 132 loplugin::Plugin::Registration< CommaOperator > X("commaoperator", true);
 133
 134 }
 135
 136 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */