/// Warns on methods overridden in DerivedDecl with respect to BaseDecl.
/// FIXME: this warns on all overrides outside of the sliced path in case of
/// multiple inheritance.
void SlicingCheck::DiagnoseSlicedOverriddenMethods(
const Expr &Call, const CXXRecordDecl &DerivedDecl,
const CXXRecordDecl &BaseDecl) {
if (DerivedDecl.getCanonicalDecl() == BaseDecl.getCanonicalDecl())
return;
for (const auto &Method : DerivedDecl.methods()) {
// Virtual destructors are OK. We're ignoring constructors since they are
// tagged as overrides.
if (isa<CXXConstructorDecl>(Method) || isa<CXXDestructorDecl>(Method))
continue;
if (Method->size_overridden_methods() > 0) {
diag(Call.getExprLoc(),
"slicing object from type %0 to %1 discards override %2")
<< &DerivedDecl << &BaseDecl << Method;
}
}
// Recursively process bases.
for (const auto &Base : DerivedDecl.bases()) {
if (const auto *BaseRecordType = Base.getType()->getAs<RecordType>()) {
if (const auto *BaseRecord = cast_or_null<CXXRecordDecl>(
BaseRecordType->getDecl()->getDefinition()))
DiagnoseSlicedOverriddenMethods(Call, *BaseRecord, BaseDecl);
}
}
}
static bool isParentOf(const CXXRecordDecl &Parent,
const CXXRecordDecl &ThisClass) {
if (Parent.getCanonicalDecl() == ThisClass.getCanonicalDecl())
return true;
const CXXRecordDecl *ParentCanonicalDecl = Parent.getCanonicalDecl();
return ThisClass.bases_end() !=
llvm::find_if(ThisClass.bases(), [=](const CXXBaseSpecifier &Base) {
auto *BaseDecl = Base.getType()->getAsCXXRecordDecl();
assert(BaseDecl);
return ParentCanonicalDecl == BaseDecl->getCanonicalDecl();
});
}
/// Determines whether the accessed entity is accessible. Public members
/// have been weeded out by this point.
static AccessResult IsAccessible(Sema &S,
const EffectiveContext &EC,
AccessTarget &Entity) {
// Determine the actual naming class.
CXXRecordDecl *NamingClass = Entity.getNamingClass();
while (NamingClass->isAnonymousStructOrUnion())
NamingClass = cast<CXXRecordDecl>(NamingClass->getParent());
NamingClass = NamingClass->getCanonicalDecl();
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 privileged access.
if (UnprivilegedAccess != AS_none) {
switch (HasAccess(S, EC, NamingClass, UnprivilegedAccess, Entity)) {
case 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 AR_dependent;
case AR_accessible: return AR_accessible;
case AR_inaccessible: break;
}
}
AccessTarget::SavedInstanceContext _ = Entity.saveInstanceContext();
// We lower member accesses to base accesses by pretending that the
// member is a base class of its declaring class.
AccessSpecifier FinalAccess;
if (Entity.isMemberAccess()) {
// Determine if the declaration is accessible from EC when named
// in its declaring class.
NamedDecl *Target = Entity.getTargetDecl();
const CXXRecordDecl *DeclaringClass = Entity.getDeclaringClass();
FinalAccess = Target->getAccess();
switch (HasAccess(S, EC, DeclaringClass, FinalAccess, Entity)) {
case AR_accessible:
FinalAccess = AS_public;
break;
case AR_inaccessible: break;
case AR_dependent: return AR_dependent; // see above
}
if (DeclaringClass == NamingClass)
return (FinalAccess == AS_public ? AR_accessible : AR_inaccessible);
Entity.suppressInstanceContext();
} else {
FinalAccess = AS_public;
}
assert(Entity.getDeclaringClass() != NamingClass);
// Append the declaration's access if applicable.
CXXBasePaths Paths;
CXXBasePath *Path = FindBestPath(S, EC, Entity, FinalAccess, Paths);
if (!Path)
return AR_dependent;
assert(Path->Access <= UnprivilegedAccess &&
"access along best path worse than direct?");
if (Path->Access == AS_public)
return AR_accessible;
return AR_inaccessible;
}