compilerplugins/clang/staticconstfield.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 "plugin.hxx"
  11 #include "check.hxx"
  12 #include "compat.hxx"
  13 #include <iostream>
  14 #include <unordered_map>
  15 #include <unordered_set>
  16 #include <vector>
  17
  18 /**
  19  Look for fields which are const, which can be made static const
  20 */
  21 namespace
  22 {
  23 class StaticConstField : public loplugin::FilteringPlugin<StaticConstField>
  24 {
  25 public:
  26     explicit StaticConstField(loplugin::InstantiationData const& data)
  27         : loplugin::FilteringPlugin<StaticConstField>(data)
  28     {
  29     }
  30
  31     void run() override;
  32
  33     bool TraverseConstructorInitializer(CXXCtorInitializer* init);
  34     bool TraverseCXXConstructorDecl(CXXConstructorDecl* decl);
  35
  36 private:
  37     struct Data
  38     {
  39         std::vector<CXXCtorInitializer const*> inits;
  40         std::string value;
  41     };
  42     std::unordered_map<FieldDecl const*, Data> m_potentials;
  43     std::unordered_set<FieldDecl const*> m_excluded;
  44     CXXConstructorDecl* m_currentConstructor = nullptr;
  45 };
  46
  47 void StaticConstField::run()
  48 {
  49     std::string fn = handler.getMainFileName().str();
  50     loplugin::normalizeDotDotInFilePath(fn);
  51
  52     // unusual case where a user constructor sets a field to one value, and a copy constructor sets it to a different value
  53     if (fn == SRCDIR "/sw/source/core/attr/hints.cxx")
  54         return;
  55     if (fn == SRCDIR "/oox/source/core/contexthandler2.cxx")
  56         return;
  57
  58     TraverseDecl(compiler.getASTContext().getTranslationUnitDecl());
  59
  60     for (auto const& pair : m_potentials)
  61     {
  62         report(DiagnosticsEngine::Error, "const field can be static", pair.first->getLocation())
  63             << pair.first->getSourceRange();
  64         for (CXXCtorInitializer const* init : pair.second.inits)
  65             if (pair.first->getLocation() != init->getSourceLocation())
  66                 report(DiagnosticsEngine::Note, "init here", init->getSourceLocation())
  67                     << init->getSourceRange();
  68     }
  69 }
  70
  71 bool StaticConstField::TraverseCXXConstructorDecl(CXXConstructorDecl* decl)
  72 {
  73     auto prev = m_currentConstructor;
  74     m_currentConstructor = decl;
  75     bool ret = FilteringPlugin::TraverseCXXConstructorDecl(decl);
  76     m_currentConstructor = prev;
  77     return ret;
  78 }
  79
  80 bool StaticConstField::TraverseConstructorInitializer(CXXCtorInitializer* init)
  81 {
  82     if (!init->getSourceLocation().isValid() || ignoreLocation(init->getSourceLocation()))
  83         return true;
  84     if (!init->getMember())
  85         return true;
  86     if (!init->getInit())
  87         return true;
  88     if (!m_currentConstructor || m_currentConstructor->isCopyOrMoveConstructor())
  89         return true;
  90     if (!m_currentConstructor->getParent()->isCompleteDefinition())
  91         return true;
  92     if (m_excluded.find(init->getMember()) != m_excluded.end())
  93         return true;
  94     auto type = init->getMember()->getType();
  95     auto tc = loplugin::TypeCheck(type);
  96     if (!tc.Const())
  97         return true;
  98
  99     bool found = false;
 100     std::string value;
 101     auto const initexpr = init->getInit()->IgnoreImplicit();
 102     if (tc.Const().Class("OUString").Namespace("rtl").GlobalNamespace()
 103         || tc.Const().Class("OString").Namespace("rtl").GlobalNamespace())
 104     {
 105         if (auto constructExpr = dyn_cast<CXXConstructExpr>(initexpr))
 106         {
 107             if (constructExpr->getNumArgs() >= 1
 108                 && isa<clang::StringLiteral>(constructExpr->getArg(0)))
 109             {
 110                 value = dyn_cast<clang::StringLiteral>(constructExpr->getArg(0))->getString().str();
 111                 found = true;
 112             }
 113         }
 114     }
 115     else if (type->isFloatingType())
 116     {
 117         APFloat x1(0.0f);
 118         if (initexpr->EvaluateAsFloat(x1, compiler.getASTContext()))
 119         {
 120             std::string s;
 121             llvm::raw_string_ostream os(s);
 122             x1.print(os);
 123             value = os.str();
 124             found = true;
 125         }
 126     }
 127     // ignore this, it seems to trigger an infinite recursion
 128     else if (isa<UnaryExprOrTypeTraitExpr>(initexpr))
 129         ;
 130     // ignore this, calling EvaluateAsInt on it will crash clang
 131     else if (initexpr->isValueDependent())
 132         ;
 133     else
 134     {
 135         APSInt x1;
 136         if (compat::EvaluateAsInt(initexpr, x1, compiler.getASTContext()))
 137         {
 138             value = compat::toString(x1, 10);
 139             found = true;
 140         }
 141     }
 142
 143     if (!found)
 144     {
 145         m_potentials.erase(init->getMember());
 146         m_excluded.insert(init->getMember());
 147         return true;
 148     }
 149
 150     auto findIt = m_potentials.find(init->getMember());
 151     if (findIt != m_potentials.end())
 152     {
 153         if (findIt->second.value != value)
 154         {
 155             m_potentials.erase(findIt);
 156             m_excluded.insert(init->getMember());
 157         }
 158         else
 159             findIt->second.inits.push_back(init);
 160     }
 161     else
 162     {
 163         Data& data = m_potentials[init->getMember()];
 164         data.inits.push_back(init);
 165         data.value = value;
 166     }
 167
 168     return true;
 169 }
 170
 171 loplugin::Plugin::Registration<StaticConstField> X("staticconstfield", true);
 172 }
 173
 174 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */