compilerplugins/clang/getstr.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
   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 #ifndef LO_CLANG_SHARED_PLUGINS
  11
  12 #include <cassert>
  13 #include <stack>
  14
  15 #include "check.hxx"
  16 #include "plugin.hxx"
  17
  18 // Find matches of
  19 //
  20 //   ... << s.getStr()
  21 //
  22 // (for the rtl string classes) that can be written as just
  23 //
  24 //   ... << s
  25
  26 namespace
  27 {
  28 class GetStr final : public loplugin::FilteringPlugin<GetStr>
  29 {
  30 public:
  31     explicit GetStr(loplugin::InstantiationData const& data)
  32         : FilteringPlugin(data)
  33     {
  34     }
  35
  36     bool PreTraverseFunctionDecl(FunctionDecl* decl)
  37     {
  38         functions_.push(decl);
  39         return true;
  40     }
  41
  42     bool PostTraverseFunctionDecl(FunctionDecl*, bool)
  43     {
  44         assert(!functions_.empty());
  45         functions_.pop();
  46         return true;
  47     }
  48
  49     bool TraverseFunctionDecl(FunctionDecl* decl)
  50     {
  51         bool ret = true;
  52         if (PreTraverseFunctionDecl(decl))
  53         {
  54             ret = FilteringPlugin::TraverseFunctionDecl(decl);
  55             PostTraverseFunctionDecl(decl, ret);
  56         }
  57         return ret;
  58     }
  59
  60     bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr* expr)
  61     {
  62         if (ignoreLocation(expr))
  63         {
  64             return true;
  65         }
  66         if (expr->getOperator() != OO_LessLess)
  67         {
  68             return true;
  69         }
  70         assert(expr->getNumArgs() == 2);
  71         if (!loplugin::TypeCheck(expr->getArg(0)->getType())
  72                  .ClassOrStruct("basic_ostream")
  73                  .StdNamespace()) //TODO: check template args
  74         {
  75             return true;
  76         }
  77         auto const arg1 = expr->getArg(1);
  78         auto const e = dyn_cast<CXXMemberCallExpr>(arg1->IgnoreParenImpCasts());
  79         if (e == nullptr)
  80         {
  81             return true;
  82         }
  83         bool castToVoid = false;
  84         if (auto const ic = dyn_cast<ImplicitCastExpr>(arg1))
  85         {
  86             if (loplugin::TypeCheck(arg1->getType()).Pointer().Void())
  87             {
  88                 castToVoid = true;
  89             }
  90         }
  91         auto const t = e->getObjectType();
  92         auto const tc = loplugin::TypeCheck(t);
  93         if (!(tc.Class("OString").Namespace("rtl").GlobalNamespace()
  94               || tc.Class("OUString").Namespace("rtl").GlobalNamespace()
  95               || (castToVoid
  96                   && (tc.Class("OStringBuffer").Namespace("rtl").GlobalNamespace()
  97                       || tc.Class("OUStringBuffer").Namespace("rtl").GlobalNamespace()))))
  98         {
  99             return true;
 100         }
 101         if (!loplugin::DeclCheck(e->getMethodDecl()).Function("getStr"))
 102         {
 103             return true;
 104         }
 105         if (castToVoid)
 106         {
 107             report(DiagnosticsEngine::Warning,
 108                    ("suspicious use of 'getStr' on an object of type %0; the result is implicitly"
 109                     " cast to a void pointer in a call of 'operator <<'"),
 110                    e->getExprLoc())
 111                 << t.getLocalUnqualifiedType() << expr->getSourceRange();
 112             return true;
 113         }
 114         if (!functions_.empty())
 115         {
 116             // Filter out occurrences of `s << t.getStr()` in the implementation of
 117             // `operator <<(std::basic_ostream<...> & s, T const & t)`:
 118             auto const fd = functions_.top();
 119             if (fd->getOverloadedOperator() == OO_LessLess)
 120             {
 121                 assert(fd->getNumParams() == 2);
 122                 if (loplugin::TypeCheck(fd->getParamDecl(0)->getType())
 123                         .LvalueReference()
 124                         .NonConstVolatile()
 125                         .TemplateSpecializationClass()
 126                         .ClassOrStruct("basic_ostream")
 127                         .StdNamespace()) //TODO: check template args
 128                 {
 129                     if (auto const t2
 130                         = fd->getParamDecl(1)->getType()->getAs<LValueReferenceType>())
 131                     {
 132                         auto const t3 = t2->getPointeeType();
 133                         if (t3.isConstQualified() && !t3.isVolatileQualified()
 134                             && (t3.getCanonicalType().getTypePtr()
 135                                 == t.getCanonicalType().getTypePtr()))
 136                         {
 137                             return true;
 138                         }
 139                     }
 140                 }
 141             }
 142         }
 143         report(DiagnosticsEngine::Warning,
 144                ("directly use object of type %0 in a call of 'operator <<', instead of calling"
 145                 " 'getStr' first"),
 146                e->getExprLoc())
 147             << t.getLocalUnqualifiedType() << expr->getSourceRange();
 148         return true;
 149     }
 150
 151     bool preRun() override { return compiler.getLangOpts().CPlusPlus; }
 152
 153 private:
 154     std::stack<FunctionDecl*> functions_;
 155
 156     void run() override
 157     {
 158         if (preRun())
 159         {
 160             TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
 161         }
 162     }
 163 };
 164
 165 loplugin::Plugin::Registration<GetStr> getstr("getstr");
 166 }
 167
 168 #endif
 169
 170 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */