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Correct the calculation of access to more closely model the wording in 

the standard.

llvm-svn: 100155
This commit is contained in:
John McCall 2010-04-02 00:03:43 +00:00
parent cbcb692133
commit d79b4d8173
2 changed files with 269 additions and 127 deletions
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337
clang/lib/Sema/SemaAccess.cpp
View File

@ -370,10 +370,6 @@ static Sema::AccessResult MatchesFriend(Sema &S,
static Sema::AccessResult GetFriendKind(Sema &S,
const EffectiveContext &EC,
const CXXRecordDecl *Class) {
// A class always has access to its own members.
if (EC.includesClass(Class))
return Sema::AR_accessible;
Sema::AccessResult OnFailure = Sema::AR_inaccessible;
// Okay, check friends.
@ -401,9 +397,88 @@ static Sema::AccessResult GetFriendKind(Sema &S,
return OnFailure;
}
static Sema::AccessResult HasAccess(Sema &S,
const EffectiveContext &EC,
const CXXRecordDecl *NamingClass,
AccessSpecifier Access) {
assert(NamingClass->getCanonicalDecl() == NamingClass &&
"declaration should be canonicalized before being passed here");
if (Access == AS_public) return Sema::AR_accessible;
assert(Access == AS_private || Access == AS_protected);
for (EffectiveContext::record_iterator
I = EC.Records.begin(), E = EC.Records.end(); I != E; ++I) {
// All the declarations in EC have been canonicalized, so pointer
// equality from this point on will work fine.
const CXXRecordDecl *ECRecord = *I;
// [B2] and [M2]
if (ECRecord == NamingClass)
return Sema::AR_accessible;
// [B3] and [M3]
if (Access == AS_protected &&
ECRecord->isDerivedFrom(const_cast<CXXRecordDecl*>(NamingClass)))
return Sema::AR_accessible;
}
return GetFriendKind(S, EC, NamingClass);
}
/// 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_none if
/// there is no final step.
/// \return null if friendship is dependent
@ -445,20 +520,15 @@ static CXXBasePath *FindBestPath(Sema &S,
}
AccessSpecifier BaseAccess = I->Base->getAccessSpecifier();
if (BaseAccess != AS_public || PathAccess != AS_public) {
switch (GetFriendKind(S, EC, I->Class)) {
case Sema::AR_inaccessible:
PathAccess = CXXRecordDecl::MergeAccess(BaseAccess, PathAccess);
break;
case Sema::AR_accessible:
PathAccess = AS_public;
break;
case Sema::AR_dependent:
AnyDependent = true;
goto Next;
case Sema::AR_delayed:
llvm_unreachable("friend resolution is never delayed"); break;
}
PathAccess = std::max(PathAccess, BaseAccess);
switch (HasAccess(S, EC, I->Class, PathAccess)) {
case Sema::AR_inaccessible: break;
case Sema::AR_accessible: PathAccess = AS_public; break;
case Sema::AR_dependent:
AnyDependent = true;
goto Next;
case Sema::AR_delayed:
llvm_unreachable("friend resolution is never delayed"); break;
}
}
@ -491,16 +561,27 @@ static CXXBasePath *FindBestPath(Sema &S,
/// to become inaccessible.
static void DiagnoseAccessPath(Sema &S,
const EffectiveContext &EC,
CXXRecordDecl *NamingClass,
CXXRecordDecl *DeclaringClass,
NamedDecl *D, AccessSpecifier Access) {
const Sema::AccessedEntity &Entity) {
AccessSpecifier Access = Entity.getAccess();
CXXRecordDecl *NamingClass = Entity.getNamingClass();
NamingClass = NamingClass->getCanonicalDecl();
NamedDecl *D;
CXXRecordDecl *DeclaringClass;
if (Entity.isMemberAccess()) {
D = Entity.getTargetDecl();
DeclaringClass = FindDeclaringClass(D);
} else {
D = 0;
DeclaringClass = Entity.getBaseClass();
}
DeclaringClass = DeclaringClass->getCanonicalDecl();
// Easy case: the decl's natural access determined its path access.
// We have to check against AS_private here in case Access is AS_none,
// indicating a non-public member of a private base class.
//
// DependentFriend should be impossible here.
if (D && (Access == D->getAccess() || D->getAccess() == AS_private)) {
switch (GetFriendKind(S, EC, DeclaringClass)) {
switch (HasAccess(S, EC, DeclaringClass, D->getAccess())) {
case Sema::AR_inaccessible: {
S.Diag(D->getLocation(), diag::note_access_natural)
<< (unsigned) (Access == AS_protected)
@ -566,101 +647,113 @@ static void DiagnoseAccessPath(Sema &S,
llvm_unreachable("access not apparently constrained by path");
}
/// Diagnose an inaccessible class member.
static void DiagnoseInaccessibleMember(Sema &S, SourceLocation Loc,
const EffectiveContext &EC,
CXXRecordDecl *NamingClass,
AccessSpecifier Access,
const Sema::AccessedEntity &Entity) {
NamedDecl *D = Entity.getTargetDecl();
CXXRecordDecl *DeclaringClass = FindDeclaringClass(D);
S.Diag(Loc, Entity.getDiag())
<< (Access == AS_protected)
<< D->getDeclName()
<< S.Context.getTypeDeclType(NamingClass)
<< S.Context.getTypeDeclType(DeclaringClass);
DiagnoseAccessPath(S, EC, NamingClass, DeclaringClass, D, Access);
}
/// Diagnose an inaccessible hierarchy conversion.
static void DiagnoseInaccessibleBase(Sema &S, SourceLocation Loc,
const EffectiveContext &EC,
AccessSpecifier Access,
const Sema::AccessedEntity &Entity) {
S.Diag(Loc, Entity.getDiag())
<< (Access == AS_protected)
<< DeclarationName()
<< S.Context.getTypeDeclType(Entity.getDerivedClass())
<< S.Context.getTypeDeclType(Entity.getBaseClass());
DiagnoseAccessPath(S, EC, Entity.getDerivedClass(),
Entity.getBaseClass(), 0, Access);
}
static void DiagnoseBadAccess(Sema &S, SourceLocation Loc,
const EffectiveContext &EC,
CXXRecordDecl *NamingClass,
AccessSpecifier Access,
const Sema::AccessedEntity &Entity) {
if (Entity.isMemberAccess())
DiagnoseInaccessibleMember(S, Loc, EC, NamingClass, Access, Entity);
else
DiagnoseInaccessibleBase(S, Loc, EC, Access, Entity);
const CXXRecordDecl *NamingClass = Entity.getNamingClass();
NamedDecl *D;
const CXXRecordDecl *DeclaringClass;
if (Entity.isMemberAccess()) {
D = Entity.getTargetDecl();
DeclaringClass = FindDeclaringClass(D);
} else {
D = 0;
DeclaringClass = Entity.getBaseClass();
}
S.Diag(Loc, Entity.getDiag())
<< (Entity.getAccess() == AS_protected)
<< (D ? D->getDeclName() : DeclarationName())
<< S.Context.getTypeDeclType(NamingClass)
<< S.Context.getTypeDeclType(DeclaringClass);
DiagnoseAccessPath(S, EC, Entity);
}
/// Determines whether the accessed entity is accessible. Public members
/// have been weeded out by this point.
static Sema::AccessResult IsAccessible(Sema &S,
const EffectiveContext &EC,
const Sema::AccessedEntity &Entity) {
// Determine the actual naming class.
CXXRecordDecl *NamingClass = Entity.getNamingClass();
while (NamingClass->isAnonymousStructOrUnion())
NamingClass = cast<CXXRecordDecl>(NamingClass->getParent());
NamingClass = NamingClass->getCanonicalDecl();
/// Try to elevate access using friend declarations. This is
/// potentially quite expensive.
///
/// \return true if elevation was dependent
static bool TryElevateAccess(Sema &S,
const EffectiveContext &EC,
const Sema::AccessedEntity &Entity,
AccessSpecifier &Access) {
AccessSpecifier UnprivilegedAccess = Entity.getAccess();
assert(UnprivilegedAccess != AS_public && "public access not weeded out");
// Before we try to recalculate access paths, try to white-list
// accesses which just trade in on the final step, i.e. accesses
// which don't require [M4] or [B4]. These are by far the most
// common forms of access.
if (UnprivilegedAccess != AS_none) {
switch (HasAccess(S, EC, NamingClass, UnprivilegedAccess)) {
case Sema::AR_dependent:
// This is actually an interesting policy decision. We don't
// *have* to delay immediately here: we can do the full access
// calculation in the hope that friendship on some intermediate
// class will make the declaration accessible non-dependently.
// But that's not cheap, and odds are very good (note: assertion
// made without data) that the friend declaration will determine
// access.
return Sema::AR_dependent;
case Sema::AR_accessible: return Sema::AR_accessible;
case Sema::AR_inaccessible: break;
case Sema::AR_delayed:
llvm_unreachable("friendship never subject to contextual delay");
}
}
// Determine the declaring class.
CXXRecordDecl *DeclaringClass;
if (Entity.isMemberAccess()) {
DeclaringClass = FindDeclaringClass(Entity.getTargetDecl());
} else {
DeclaringClass = Entity.getBaseClass();
}
CXXRecordDecl *NamingClass = Entity.getNamingClass();
DeclaringClass = DeclaringClass->getCanonicalDecl();
// We lower member accesses to base accesses by pretending that the
// member is a base class of its declaring class.
AccessSpecifier FinalAccess;
// Adjust the declaration of the referred entity.
AccessSpecifier DeclAccess = AS_public;
if (Entity.isMemberAccess()) {
// Determine if the declaration is accessible from EC when named
// in its declaring class.
NamedDecl *Target = Entity.getTargetDecl();
DeclAccess = Target->getAccess();
if (DeclAccess != AS_public) {
switch (GetFriendKind(S, EC, DeclaringClass)) {
case Sema::AR_accessible: DeclAccess = AS_public; break;
case Sema::AR_inaccessible: break;
case Sema::AR_dependent: return true;
case Sema::AR_delayed: llvm_unreachable("friend status is never delayed");
}
FinalAccess = Target->getAccess();
switch (HasAccess(S, EC, DeclaringClass, FinalAccess)) {
case Sema::AR_accessible: FinalAccess = AS_public; break;
case Sema::AR_inaccessible: break;
case Sema::AR_dependent: return Sema::AR_dependent; // see above
case Sema::AR_delayed: llvm_unreachable("friend status is never delayed");
}
if (DeclaringClass == NamingClass) {
Access = DeclAccess;
return false;
}
if (DeclaringClass == NamingClass)
return (FinalAccess == AS_public
? Sema::AR_accessible
: Sema::AR_inaccessible);
} else {
FinalAccess = AS_public;
}
assert(DeclaringClass != NamingClass);
// Append the declaration's access if applicable.
CXXBasePaths Paths;
CXXBasePath *Path = FindBestPath(S, EC, Entity.getNamingClass(),
DeclaringClass, DeclAccess, Paths);
CXXBasePath *Path = FindBestPath(S, EC, NamingClass, DeclaringClass,
FinalAccess, Paths);
if (!Path)
return true;
return Sema::AR_dependent;
// Grab the access along the best path (note that this includes the
// final-step access).
AccessSpecifier NewAccess = Path->Access;
assert(NewAccess <= Access && "access along best path worse than direct?");
Access = NewAccess;
return false;
assert(Path->Access <= UnprivilegedAccess &&
"access along best path worse than direct?");
if (Path->Access == AS_public)
return Sema::AR_accessible;
return Sema::AR_inaccessible;
}
static void DelayAccess(Sema &S,
@ -683,47 +776,37 @@ static void DelayAccess(Sema &S,
static Sema::AccessResult CheckEffectiveAccess(Sema &S,
const EffectiveContext &EC,
SourceLocation Loc,
Sema::AccessedEntity const &Entity) {
AccessSpecifier Access = Entity.getAccess();
assert(Access != AS_public && "called for public access!");
const Sema::AccessedEntity &Entity) {
assert(Entity.getAccess() != AS_public && "called for public access!");
// Find a non-anonymous naming class. For records with access,
// there should always be one of these.
CXXRecordDecl *NamingClass = Entity.getNamingClass();
while (NamingClass->isAnonymousStructOrUnion())
NamingClass = cast<CXXRecordDecl>(NamingClass->getParent());
// White-list accesses from classes with privileges equivalent to the
// naming class --- but only if the access path isn't forbidden
// (i.e. an access of a private member from a subclass).
if (Access != AS_none && EC.includesClass(NamingClass))
return Sema::AR_accessible;
// Try to elevate access.
// TODO: on some code, it might be better to do the protected check
// without trying to elevate first.
if (TryElevateAccess(S, EC, Entity, Access)) {
switch (IsAccessible(S, EC, Entity)) {
case Sema::AR_dependent:
DelayAccess(S, EC, Loc, Entity);
return Sema::AR_dependent;
case Sema::AR_delayed:
llvm_unreachable("IsAccessible cannot contextually delay");
case Sema::AR_inaccessible:
if (!Entity.isQuiet())
DiagnoseBadAccess(S, Loc, EC, Entity);
return Sema::AR_inaccessible;
case Sema::AR_accessible:
break;
}
if (Access == AS_public) return Sema::AR_accessible;
// Protected access.
if (Access == AS_protected) {
// FIXME: implement [class.protected]p1
for (llvm::SmallVectorImpl<CXXRecordDecl*>::const_iterator
I = EC.Records.begin(), E = EC.Records.end(); I != E; ++I)
if ((*I)->isDerivedFrom(NamingClass))
return Sema::AR_accessible;
// FIXME: delay if we can't decide class derivation yet.
// We only consider the natural access of the declaration when
// deciding whether to do the protected check.
if (Entity.isMemberAccess() && Entity.getAccess() == AS_protected) {
NamedDecl *D = Entity.getTargetDecl();
if (isa<FieldDecl>(D) ||
(isa<CXXMethodDecl>(D) && cast<CXXMethodDecl>(D)->isInstance())) {
// FIXME: implement [class.protected]
}
}
// Okay, that's it, reject it.
if (!Entity.isQuiet())
DiagnoseBadAccess(S, Loc, EC, NamingClass, Access, Entity);
return Sema::AR_inaccessible;
return Sema::AR_accessible;
}
static Sema::AccessResult CheckAccess(Sema &S, SourceLocation Loc,

59
clang/test/CXX/class.access/class.access.base/p5.cpp Normal file
View File

@ -0,0 +1,59 @@
// RUN: %clang_cc1 -faccess-control -verify %s
namespace test0 {
struct A {
static int x;
};
struct B : A {};
struct C : B {};
int test() {
return A::x
+ B::x
+ C::x;
}
}
namespace test1 {
struct A {
private: static int x; // expected-note 5 {{declared private here}}
static int test() { return x; }
};
struct B : public A {
static int test() { return x; } // expected-error {{private member}}
};
struct C : private A {
static int test() { return x; } // expected-error {{private member}}
};
struct D {
public: static int x;
static int test() { return x; }
};
struct E : private D { // expected-note{{constrained by private inheritance}}
static int test() { return x; }
};
int test() {
return A::x // expected-error {{private member}}
+ B::x // expected-error {{private member}}
+ C::x // expected-error {{private member}}
+ D::x
+ E::x; // expected-error {{private member}}
}
}
namespace test2 {
class A {
protected: static int x;
};
class B : private A {}; // expected-note {{private inheritance}}
class C : private A {
int test(B *b) {
return b->x; // expected-error {{private member}}
}
};
}
// TODO: flesh out these cases