compilerplugins/clang/stringviewdangle.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 #ifndef LO_CLANG_SHARED_PLUGINS
  10
  11 #include <cassert>
  12 #include <string>
  13 #include <iostream>
  14 #include <unordered_map>
  15 #include <unordered_set>
  16
  17 #include "plugin.hxx"
  18 #include "check.hxx"
  19 #include "compat.hxx"
  20 #include "config_clang.h"
  21 #include "clang/AST/CXXInheritance.h"
  22 #include "clang/AST/StmtVisitor.h"
  23
  24 /**
  25 Look for places where we are assigning a temporary O[U]String to a std::*string_view, which leads
  26 to a view pointing to freed memory.
  27 */
  28
  29 namespace
  30 {
  31 class StringViewDangle : public loplugin::FilteringPlugin<StringViewDangle>
  32 {
  33 public:
  34     explicit StringViewDangle(loplugin::InstantiationData const& data)
  35         : FilteringPlugin(data)
  36     {
  37     }
  38
  39     bool preRun() override { return true; }
  40
  41     virtual void run() override
  42     {
  43         if (!preRun())
  44             return;
  45         TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  46     }
  47
  48     bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr const*);
  49     bool VisitVarDecl(VarDecl const*);
  50 };
  51
  52 static const Expr* IgnoreImplicitAndConversionOperator(const Expr* expr)
  53 {
  54     expr = expr->IgnoreImplicit();
  55     if (auto memberCall = dyn_cast<CXXMemberCallExpr>(expr))
  56     {
  57         if (auto conversionDecl = dyn_cast_or_null<CXXConversionDecl>(memberCall->getMethodDecl()))
  58         {
  59             if (!conversionDecl->isExplicit())
  60                 expr = memberCall->getImplicitObjectArgument()->IgnoreImpCasts();
  61         }
  62     }
  63     return expr;
  64 }
  65
  66 bool StringViewDangle::VisitCXXOperatorCallExpr(CXXOperatorCallExpr const* cxxOperatorCallExpr)
  67 {
  68     if (ignoreLocation(cxxOperatorCallExpr))
  69         return true;
  70
  71     auto op = cxxOperatorCallExpr->getOperator();
  72     if (op != OO_Equal)
  73         return true;
  74     if (!loplugin::TypeCheck(cxxOperatorCallExpr->getType())
  75              .ClassOrStruct("basic_string_view")
  76              .StdNamespace())
  77         return true;
  78     auto expr = IgnoreImplicitAndConversionOperator(cxxOperatorCallExpr->getArg(1));
  79     auto tc = loplugin::TypeCheck(expr->getType());
  80     if (!tc.Class("OUString").Namespace("rtl").GlobalNamespace()
  81         && !tc.Class("OString").Namespace("rtl").GlobalNamespace())
  82         return true;
  83     if (!isa<MaterializeTemporaryExpr>(expr))
  84         return true;
  85     report(DiagnosticsEngine::Warning, "view pointing into temporary i.e. dangling",
  86            cxxOperatorCallExpr->getExprLoc())
  87         << cxxOperatorCallExpr->getSourceRange();
  88     return true;
  89 }
  90
  91 bool StringViewDangle::VisitVarDecl(VarDecl const* varDecl)
  92 {
  93     if (ignoreLocation(varDecl))
  94         return true;
  95     if (!loplugin::TypeCheck(varDecl->getType()).ClassOrStruct("basic_string_view").StdNamespace())
  96         return true;
  97     if (!varDecl->hasInit())
  98         return true;
  99     auto expr = IgnoreImplicitAndConversionOperator(varDecl->getInit());
 100     auto tc = loplugin::TypeCheck(expr->getType());
 101     if (!tc.Class("OUString").Namespace("rtl").GlobalNamespace()
 102         && !tc.Class("OString").Namespace("rtl").GlobalNamespace())
 103         return true;
 104     if (!isa<MaterializeTemporaryExpr>(expr))
 105         return true;
 106     report(DiagnosticsEngine::Warning, "view pointing into temporary i.e. dangling",
 107            varDecl->getLocation())
 108         << varDecl->getSourceRange();
 109     return true;
 110 }
 111
 112 loplugin::Plugin::Registration<StringViewDangle> stringviewdangle("stringviewdangle");
 113 }
 114
 115 #endif // LO_CLANG_SHARED_PLUGINS
 116
 117 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */