bool CXXRecordDecl::lookupInBases(BaseMatchesCallback *BaseMatches,
void *UserData,
CXXBasePaths &Paths) const {
// If we didn't find anything, report that.
if (!Paths.lookupInBases(getASTContext(), this, BaseMatches, UserData))
return false;
// If we're not recording paths or we won't ever find ambiguities,
// we're done.
if (!Paths.isRecordingPaths() || !Paths.isFindingAmbiguities())
return true;
// C++ [class.member.lookup]p6:
// When virtual base classes are used, a hidden declaration can be
// reached along a path through the sub-object lattice that does
// not pass through the hiding declaration. This is not an
// ambiguity. The identical use with nonvirtual base classes is an
// ambiguity; in that case there is no unique instance of the name
// that hides all the others.
//
// FIXME: This is an O(N^2) algorithm, but DPG doesn't see an easy
// way to make it any faster.
for (CXXBasePaths::paths_iterator P = Paths.begin(), PEnd = Paths.end();
P != PEnd; /* increment in loop */) {
bool Hidden = false;
for (CXXBasePath::iterator PE = P->begin(), PEEnd = P->end();
PE != PEEnd && !Hidden; ++PE) {
if (PE->Base->isVirtual()) {
CXXRecordDecl *VBase = 0;
if (const RecordType *Record = PE->Base->getType()->getAs<RecordType>())
VBase = cast<CXXRecordDecl>(Record->getDecl());
if (!VBase)
break;
// The declaration(s) we found along this path were found in a
// subobject of a virtual base. Check whether this virtual
// base is a subobject of any other path; if so, then the
// declaration in this path are hidden by that patch.
for (CXXBasePaths::paths_iterator HidingP = Paths.begin(),
HidingPEnd = Paths.end();
HidingP != HidingPEnd;
++HidingP) {
CXXRecordDecl *HidingClass = 0;
if (const RecordType *Record
= HidingP->back().Base->getType()->getAs<RecordType>())
HidingClass = cast<CXXRecordDecl>(Record->getDecl());
if (!HidingClass)
break;
if (HidingClass->isVirtuallyDerivedFrom(VBase)) {
Hidden = true;
break;
}
}
}
}
if (Hidden)
P = Paths.Paths.erase(P);
else
++P;
}
return true;
}
/// Finds the best path from the naming class to the declaring class,
/// taking friend declarations into account.
///
/// C++0x [class.access.base]p5:
/// A member m is accessible at the point R when named in class N if
/// [M1] m as a member of N is public, or
/// [M2] m as a member of N is private, and R occurs in a member or
/// friend of class N, or
/// [M3] m as a member of N is protected, and R occurs in a member or
/// friend of class N, or in a member or friend of a class P
/// derived from N, where m as a member of P is public, private,
/// or protected, or
/// [M4] there exists a base class B of N that is accessible at R, and
/// m is accessible at R when named in class B.
///
/// C++0x [class.access.base]p4:
/// A base class B of N is accessible at R, if
/// [B1] an invented public member of B would be a public member of N, or
/// [B2] R occurs in a member or friend of class N, and an invented public
/// member of B would be a private or protected member of N, or
/// [B3] R occurs in a member or friend of a class P derived from N, and an
/// invented public member of B would be a private or protected member
/// of P, or
/// [B4] there exists a class S such that B is a base class of S accessible
/// at R and S is a base class of N accessible at R.
///
/// Along a single inheritance path we can restate both of these
/// iteratively:
///
/// First, we note that M1-4 are equivalent to B1-4 if the member is
/// treated as a notional base of its declaring class with inheritance
/// access equivalent to the member's access. Therefore we need only
/// ask whether a class B is accessible from a class N in context R.
///
/// Let B_1 .. B_n be the inheritance path in question (i.e. where
/// B_1 = N, B_n = B, and for all i, B_{i+1} is a direct base class of
/// B_i). For i in 1..n, we will calculate ACAB(i), the access to the
/// closest accessible base in the path:
/// Access(a, b) = (* access on the base specifier from a to b *)
/// Merge(a, forbidden) = forbidden
/// Merge(a, private) = forbidden
/// Merge(a, b) = min(a,b)
/// Accessible(c, forbidden) = false
/// Accessible(c, private) = (R is c) || IsFriend(c, R)
/// Accessible(c, protected) = (R derived from c) || IsFriend(c, R)
/// Accessible(c, public) = true
/// ACAB(n) = public
/// ACAB(i) =
/// let AccessToBase = Merge(Access(B_i, B_{i+1}), ACAB(i+1)) in
/// if Accessible(B_i, AccessToBase) then public else AccessToBase
///
/// B is an accessible base of N at R iff ACAB(1) = public.
///
/// \param FinalAccess the access of the "final step", or AS_public if
/// there is no final step.
/// \return null if friendship is dependent
static CXXBasePath *FindBestPath(Sema &S,
const EffectiveContext &EC,
AccessTarget &Target,
AccessSpecifier FinalAccess,
CXXBasePaths &Paths) {
// Derive the paths to the desired base.
const CXXRecordDecl *Derived = Target.getNamingClass();
const CXXRecordDecl *Base = Target.getDeclaringClass();
// FIXME: fail correctly when there are dependent paths.
bool isDerived = Derived->isDerivedFrom(const_cast<CXXRecordDecl*>(Base),
Paths);
assert(isDerived && "derived class not actually derived from base");
(void) isDerived;
CXXBasePath *BestPath = 0;
assert(FinalAccess != AS_none && "forbidden access after declaring class");
bool AnyDependent = false;
// Derive the friend-modified access along each path.
for (CXXBasePaths::paths_iterator PI = Paths.begin(), PE = Paths.end();
PI != PE; ++PI) {
AccessTarget::SavedInstanceContext _ = Target.saveInstanceContext();
// Walk through the path backwards.
AccessSpecifier PathAccess = FinalAccess;
CXXBasePath::iterator I = PI->end(), E = PI->begin();
while (I != E) {
--I;
assert(PathAccess != AS_none);
// If the declaration is a private member of a base class, there
// is no level of friendship in derived classes that can make it
// accessible.
if (PathAccess == AS_private) {
PathAccess = AS_none;
break;
}
const CXXRecordDecl *NC = I->Class->getCanonicalDecl();
AccessSpecifier BaseAccess = I->Base->getAccessSpecifier();
PathAccess = std::max(PathAccess, BaseAccess);
switch (HasAccess(S, EC, NC, PathAccess, Target)) {
case AR_inaccessible: break;
case AR_accessible:
PathAccess = AS_public;
// Future tests are not against members and so do not have
// instance context.
Target.suppressInstanceContext();
break;
case AR_dependent:
AnyDependent = true;
goto Next;
}
}
// Note that we modify the path's Access field to the
// friend-modified access.
if (BestPath == 0 || PathAccess < BestPath->Access) {
BestPath = &*PI;
BestPath->Access = PathAccess;
// Short-circuit if we found a public path.
if (BestPath->Access == AS_public)
return BestPath;
}
Next: ;
}
assert((!BestPath || BestPath->Access != AS_public) &&
"fell out of loop with public path");
// We didn't find a public path, but at least one path was subject
// to dependent friendship, so delay the check.
if (AnyDependent)
return 0;
return BestPath;
}