llvm-project/clang/lib/Sema/SemaAccess.cpp

//===---- SemaAccess.cpp - C++ Access Control -------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file provides Sema routines for C++ access control semantics.
//
//===----------------------------------------------------------------------===//

#include "SemaInherit.h"
#include "Sema.h"
#include "clang/AST/ASTContext.h"
using namespace clang;

/// SetMemberAccessSpecifier - Set the access specifier of a member.
/// Returns true on error (when the previous member decl access specifier
/// is different from the new member decl access specifier).
bool Sema::SetMemberAccessSpecifier(NamedDecl *MemberDecl, 
                                    NamedDecl *PrevMemberDecl,
                                    AccessSpecifier LexicalAS) {
  if (!PrevMemberDecl) {
    // Use the lexical access specifier.
    MemberDecl->setAccess(LexicalAS);
    return false;
  }
  
  // C++ [class.access.spec]p3: When a member is redeclared its access
  // specifier must be same as its initial declaration.
  if (LexicalAS != AS_none && LexicalAS != PrevMemberDecl->getAccess()) {
    Diag(MemberDecl->getLocation(), 
         diag::err_class_redeclared_with_different_access) 
      << MemberDecl << LexicalAS;
    Diag(PrevMemberDecl->getLocation(), diag::note_previous_access_declaration)
      << PrevMemberDecl << PrevMemberDecl->getAccess();
    return true;
  }
  
  MemberDecl->setAccess(PrevMemberDecl->getAccess());
  return false;
}

/// CheckBaseClassAccess - Check that a derived class can access its base class
/// and report an error if it can't. [class.access.base]
bool Sema::CheckBaseClassAccess(QualType Derived, QualType Base, 
                                BasePaths& Paths, SourceLocation AccessLoc) {
  Base = Context.getCanonicalType(Base).getUnqualifiedType();
  assert(!Paths.isAmbiguous(Base) && 
         "Can't check base class access if set of paths is ambiguous");
  assert(Paths.isRecordingPaths() &&
         "Can't check base class access without recorded paths");
  
  const CXXBaseSpecifier *InacessibleBase = 0;

  const CXXRecordDecl* CurrentClassDecl = 0;
  if (CXXMethodDecl *MD = dyn_cast_or_null<CXXMethodDecl>(getCurFunctionDecl()))
    CurrentClassDecl = MD->getParent();

  for (BasePaths::paths_iterator Path = Paths.begin(), PathsEnd = Paths.end(); 
      Path != PathsEnd; ++Path) {
    
    bool FoundInaccessibleBase = false;
    
    for (BasePath::const_iterator Element = Path->begin(), 
         ElementEnd = Path->end(); Element != ElementEnd; ++Element) {
      const CXXBaseSpecifier *Base = Element->Base;
      
      switch (Base->getAccessSpecifier()) {
      default:
        assert(0 && "invalid access specifier");
      case AS_public:
        // Nothing to do.
        break;
      case AS_private:
        // FIXME: Check if the current function/class is a friend.
        if (CurrentClassDecl != Element->Class)
          FoundInaccessibleBase = true;
        break;
      case AS_protected:  
        // FIXME: Implement
        break;
      }
      
      if (FoundInaccessibleBase) {
        InacessibleBase = Base;
        break;
      }
    }
    
    if (!FoundInaccessibleBase) {
      // We found a path to the base, our work here is done.
      InacessibleBase = 0;
      break;
    }
  }

  if (InacessibleBase) {
    Diag(AccessLoc, diag::err_conv_to_inaccessible_base) 
      << Derived << Base;

    AccessSpecifier AS = InacessibleBase->getAccessSpecifierAsWritten();
    
    // If there's no written access specifier, then the inheritance specifier
    // is implicitly private.
    if (AS == AS_none)
      Diag(InacessibleBase->getSourceRange().getBegin(),
           diag::note_inheritance_implicitly_private_here);
    else
      Diag(InacessibleBase->getSourceRange().getBegin(),
           diag::note_inheritance_specifier_here) << AS;

    return true;
  }
  
  return false;
}