compilerplugins/clang/store/returnbyref.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 <string>
  11 #include <set>
  12
  13 #include "compat.hxx"
  14 #include "plugin.hxx"
  15
  16 // Find places where we are returning a pointer to something, where we can be returning a reference.
  17 // e.g.
  18 //   class A {
  19 //     struct X x;
  20 //     public:
  21 //     X* getX() { return &x; }
  22 //   }
  23 // which can be:
  24 //     X& getX() { return x; }
  25
  26 namespace {
  27
  28 class ReturnByRef:
  29     public RecursiveASTVisitor<ReturnByRef>, public loplugin::Plugin
  30 {
  31 public:
  32     explicit ReturnByRef(InstantiationData const & data): Plugin(data) {}
  33
  34     virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
  35
  36     bool VisitCXXMethodDecl(const CXXMethodDecl * decl);
  37 private:
  38     std::string getFilename(SourceLocation loc);
  39 };
  40
  41 bool ReturnByRef::VisitCXXMethodDecl(const CXXMethodDecl * functionDecl) {
  42     if (ignoreLocation(functionDecl)) {
  43         return true;
  44     }
  45     if (functionDecl->isVirtual()) {
  46         return true;
  47     }
  48     if (!functionDecl->isInstance()) {
  49         return true;
  50     }
  51     if (!functionDecl->hasBody()) {
  52         return true;
  53     }
  54     // ignore stuff that forms part of the stable URE interface
  55     if (isInUnoIncludeFile(functionDecl)) {
  56         return true;
  57     }
  58     QualType t1 { compat::getReturnType(*functionDecl) };
  59     if (!t1->isPointerType()) {
  60         return true;
  61     }
  62     // Ignore stuff like:
  63     //   operator vcl::Window *(){ return &m_rWindow; }
  64     if (dyn_cast< CXXConversionDecl >( functionDecl ) != nullptr) {
  65         return true;
  66     }
  67
  68     std::string aFilename = getFilename(functionDecl->getCanonicalDecl()->getLocStart());
  69     if (aFilename == SRCDIR "/include/o3tl/cow_wrapper.hxx")
  70     {
  71         return true;
  72     }
  73     if ( functionDecl->getNameAsString() == "operator->") {
  74         return true;
  75     }
  76     /*
  77     std::string aParentName = functionDecl->getParent()->getQualifiedNameAsString();
  78     std::string fqn = aParentName + "::" + functionDecl->getNameAsString();
  79     if (aFilename == "TextCharAttribList::GetAttrib") {
  80         return true;
  81     }*/
  82
  83     /*
  84       The AST here looks like:
  85       -CompoundStmt
  86        `-ReturnStmt
  87           `-UnaryOperator
  88     */
  89
  90     const CompoundStmt* compoundStmt = dyn_cast< CompoundStmt >( functionDecl->getBody() );
  91     if (compoundStmt == nullptr || compoundStmt->body_begin() == compoundStmt->body_end()) {
  92         return true;
  93     }
  94     const ReturnStmt* returnStmt = dyn_cast<ReturnStmt>(*compoundStmt->child_begin());
  95     if (returnStmt == nullptr) {
  96         return true;
  97     }
  98
  99     const Stmt* nextStmt = dyn_cast<Expr>(*returnStmt->child_begin())->IgnoreParens();
 100     const UnaryOperator* unaryOperator = dyn_cast<UnaryOperator>(nextStmt);
 101     if (unaryOperator == nullptr || unaryOperator->getOpcode() != UO_AddrOf) {
 102         return true;
 103     }
 104 nextStmt->dump();
 105     report(
 106         DiagnosticsEngine::Warning,
 107         "rather return by reference ",
 108         functionDecl->getSourceRange().getBegin())
 109       << functionDecl->getSourceRange();
 110
 111     // display the location of the class member declaration so I don't have to search for it by hand
 112     auto otherLoc = functionDecl->getCanonicalDecl()->getSourceRange().getBegin();
 113     if (otherLoc != functionDecl->getSourceRange().getBegin())
 114     {
 115         report(
 116             DiagnosticsEngine::Note,
 117             "rather return by reference",
 118             functionDecl->getCanonicalDecl()->getSourceRange().getBegin())
 119           << functionDecl->getCanonicalDecl()->getSourceRange();
 120     }
 121
 122     return true;
 123 }
 124
 125 std::string ReturnByRef::getFilename(SourceLocation loc)
 126 {
 127     SourceLocation spellingLocation = compiler.getSourceManager().getSpellingLoc(loc);
 128     return compiler.getSourceManager().getFilename(spellingLocation);
 129 }
 130
 131 loplugin::Plugin::Registration< ReturnByRef > X("returnbyref");
 132
 133 }
 134
 135 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */