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 "plugin.hxx"
  14
  15 // Find places where we are returning a pointer to something, where we can be returning a reference.
  16 // e.g.
  17 //   class A {
  18 //     struct X x;
  19 //     public:
  20 //     X* getX() { return &x; }
  21 //   }
  22 // which can be:
  23 //     X& getX() { return x; }
  24
  25 namespace {
  26
  27 class ReturnByRef:
  28     public loplugin::FilteringPlugin<ReturnByRef>
  29 {
  30 public:
  31     explicit ReturnByRef(InstantiationData const & data): FilteringPlugin(data) {}
  32
  33     virtual void run() override { TraverseDecl(compiler.getASTContext().getTranslationUnitDecl()); }
  34
  35     bool VisitCXXMethodDecl(const CXXMethodDecl * decl);
  36 private:
  37     std::string getFilename(SourceLocation loc);
  38 };
  39
  40 bool ReturnByRef::VisitCXXMethodDecl(const CXXMethodDecl * functionDecl) {
  41     if (ignoreLocation(functionDecl)) {
  42         return true;
  43     }
  44     if (functionDecl->isVirtual()) {
  45         return true;
  46     }
  47     if (!functionDecl->isInstance()) {
  48         return true;
  49     }
  50     if (!functionDecl->hasBody()) {
  51         return true;
  52     }
  53     // ignore stuff that forms part of the stable URE interface
  54     if (isInUnoIncludeFile(functionDecl)) {
  55         return true;
  56     }
  57     QualType t1 { functionDecl->getReturnType() };
  58     if (!t1->isPointerType()) {
  59         return true;
  60     }
  61     // Ignore stuff like:
  62     //   operator vcl::Window *(){ return &m_rWindow; }
  63     if (dyn_cast< CXXConversionDecl >( functionDecl ) != nullptr) {
  64         return true;
  65     }
  66
  67     std::string aFilename = getFilename(functionDecl->getCanonicalDecl()->getLocStart());
  68     if (aFilename == SRCDIR "/include/o3tl/cow_wrapper.hxx")
  69     {
  70         return true;
  71     }
  72     if ( functionDecl->getNameAsString() == "operator->") {
  73         return true;
  74     }
  75     std::string aFunctionName = functionDecl->getQualifiedNameAsString();
  76     if (aFunctionName == "SbxValue::data") {
  77         return true;
  78     }
  79     /*
  80     std::string aParentName = functionDecl->getParent()->getQualifiedNameAsString();
  81     std::string fqn = aParentName + "::" + functionDecl->getNameAsString();
  82     if (aFilename == "TextCharAttribList::GetAttrib") {
  83         return true;
  84     }*/
  85
  86     /*
  87       The AST here looks like:
  88       -CompoundStmt
  89        `-ReturnStmt
  90           `-UnaryOperator
  91     */
  92
  93     const CompoundStmt* compoundStmt = dyn_cast< CompoundStmt >( functionDecl->getBody() );
  94     if (compoundStmt == nullptr || compoundStmt->body_begin() == compoundStmt->body_end()) {
  95         return true;
  96     }
  97     const ReturnStmt* returnStmt = dyn_cast<ReturnStmt>(*compoundStmt->child_begin());
  98     if (returnStmt == nullptr) {
  99         return true;
 100     }
 101
 102     const Stmt* nextStmt = dyn_cast<Expr>(*returnStmt->child_begin())->IgnoreParens();
 103     const UnaryOperator* unaryOperator = dyn_cast<UnaryOperator>(nextStmt);
 104     if (unaryOperator == nullptr || unaryOperator->getOpcode() != UO_AddrOf) {
 105         return true;
 106     }
 107 nextStmt->dump();
 108     report(
 109         DiagnosticsEngine::Warning,
 110         "rather return by reference ",
 111         functionDecl->getSourceRange().getBegin())
 112       << functionDecl->getSourceRange();
 113
 114     // display the location of the class member declaration so I don't have to search for it by hand
 115     auto otherLoc = functionDecl->getCanonicalDecl()->getSourceRange().getBegin();
 116     if (otherLoc != functionDecl->getSourceRange().getBegin())
 117     {
 118         report(
 119             DiagnosticsEngine::Note,
 120             "rather return by reference",
 121             functionDecl->getCanonicalDecl()->getSourceRange().getBegin())
 122           << functionDecl->getCanonicalDecl()->getSourceRange();
 123     }
 124
 125     return true;
 126 }
 127
 128 std::string ReturnByRef::getFilename(SourceLocation loc)
 129 {
 130     SourceLocation spellingLocation = compiler.getSourceManager().getSpellingLoc(loc);
 131     return compiler.getSourceManager().getFilename(spellingLocation);
 132 }
 133
 134 loplugin::Plugin::Registration< ReturnByRef > X("returnbyref");
 135
 136 }
 137
 138 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */