caio/clang-p2996
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Fix some accessibility corner case bugs.

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Anonymous structs, anonymous unions, unscoped enums. You know, all of
the most important aspects of this wonderful language of ours.
This commit is contained in:
Dan Katz
2025-04-11 16:36:04 -04:00
parent 633d86746a
commit 4ffd254378
3 changed files with 89 additions and 21 deletions
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37
clang/lib/AST/ExprConstantMeta.cpp
View File

@@ -5628,27 +5628,25 @@ bool is_accessible(APValue &Result, ASTContext &C, MetaActions &Meta,
if (!Evaluator(RV, Args[0], true))
return true;
auto validate = [&](Decl *D) -> bool {
if (!D || !D->getDeclContext() || !isa<CXXRecordDecl>(D->getDeclContext()))
return DiagnoseReflectionKind(Diagnoser, Range, "a class member");
auto validate = [&](Decl *D, CXXRecordDecl *&NamingCls) -> bool {
auto *DC = dyn_cast<CXXRecordDecl>(D->getNonTransparentDeclContext());
if (!NamingCls)
NamingCls = DC;
if (auto *Ctx = cast<CXXRecordDecl>(D->getDeclContext());
Ctx->isBeingDefined())
if (DC && DC->isBeingDefined())
return Diagnoser(Range.getBegin(),
diag::metafn_access_query_class_being_defined)
<< Ctx << Range;
<< DC << Range;
return false;
};
switch (RV.getReflectionKind()) {
case ReflectionKind::Type: {
NamedDecl *D = findTypeDecl(RV.getReflectedType());
if (validate(D))
if (validate(D, NamingCls))
return true;
if (!NamingCls)
NamingCls = cast<CXXRecordDecl>(D->getDeclContext());
else if (!NamingCls)
return SetAndSucceed(Result, makeBool(C, true));
bool Accessible = UnconditionalAccess ||
Meta.IsAccessible(D, AccessDC, NamingCls);
@@ -5656,11 +5654,10 @@ bool is_accessible(APValue &Result, ASTContext &C, MetaActions &Meta,
}
case ReflectionKind::Declaration: {
ValueDecl *D = RV.getReflectedDecl();
if (validate(D))
if (validate(D, NamingCls))
return true;
if (!NamingCls)
NamingCls = cast<CXXRecordDecl>(D->getDeclContext());
else if (!NamingCls)
return SetAndSucceed(Result, makeBool(C, true));
bool Accessible = UnconditionalAccess ||
Meta.IsAccessible(RV.getReflectedDecl(), AccessDC,
@@ -5669,11 +5666,10 @@ bool is_accessible(APValue &Result, ASTContext &C, MetaActions &Meta,
}
case ReflectionKind::Template: {
TemplateDecl *D = RV.getReflectedTemplate().getAsTemplateDecl();
if (validate(D))
if (validate(D, NamingCls))
return true;
if (!NamingCls)
NamingCls = cast<CXXRecordDecl>(D->getDeclContext());
else if (!NamingCls)
return SetAndSucceed(Result, makeBool(C, true));
bool Accessible = UnconditionalAccess ||
Meta.IsAccessible(D, AccessDC, NamingCls);
@@ -5710,8 +5706,7 @@ bool is_accessible(APValue &Result, ASTContext &C, MetaActions &Meta,
case ReflectionKind::Namespace:
case ReflectionKind::DataMemberSpec:
case ReflectionKind::Annotation:
return DiagnoseReflectionKind(Diagnoser, Range, "a class member",
DescriptionOf(RV));
return SetAndSucceed(Result, makeBool(C, true));
}
llvm_unreachable("invalid reflection type");
}

22
clang/lib/Sema/SemaReflect.cpp
View File

@@ -178,12 +178,34 @@ public:
bool IsAccessible(NamedDecl *Target, DeclContext *Ctx,
CXXRecordDecl *NamingCls) override {
bool Result = false;
// If 'Target' is a (possibly nested) anonymous struct/union or unscoped
// enumerator, replace it with its parent recursively until it's no longer
// such a member.
while (Target && Target->getDeclContext() &&
Target->getDeclContext() != NamingCls &&
[](DeclContext *DC) {
if (auto *RD = dyn_cast<CXXRecordDecl>(DC))
return RD->isAnonymousStructOrUnion();
else return DC->isTransparentContext();
}(Target->getDeclContext()))
if (isa<TranslationUnitDecl>(Target->getDeclContext()))
// Can happen if Target was a member of a static anonymous union at
// namespace scope.
return true;
else
Target = cast<NamedDecl>(Target->getDeclContext());
if (auto *Cls = dyn_cast_or_null<CXXRecordDecl>(Target->getDeclContext())) {
if (Cls != NamingCls &&
!S.IsDerivedFrom(SourceLocation{},
QualType(NamingCls->getTypeForDecl(), 0),
QualType(Cls->getTypeForDecl(), 0)))
return false;
else if (NamingCls->isAnonymousStructOrUnion())
// Clang's access-checking machinery isn't equipped to deal with checks
// where the "naming" class (ha!) is anonymous - can't imagine why!
return true;
DeclContext *PreviousDC = S.CurContext;
{

51
libcxx/test/std/experimental/reflection/member-visibility.pass.cpp
View File

@@ -288,4 +288,55 @@ static_assert(!is_private(std::meta::info{}));
static_assert(!is_private(^^int));
} // namespace queries
// ==============
// unscoped_enums
// ==============
namespace unscoped_enums {
class C {
enum { E };
public:
enum { F };
static constexpr auto r = ^^E;
};
static_assert(!is_accessible(C::r,
std::meta::access_context::unprivileged()));
static_assert(!is_accessible(C::r,
std::meta::access_context::unprivileged().via(^^C)));
static_assert(is_accessible(^^C::F,
std::meta::access_context::unprivileged()));
static_assert(is_accessible(^^C::F,
std::meta::access_context::unprivileged().via(^^C)));
} // namespace unscoped_enums
// ========================
// anonymous_structs_unions
// ========================
namespace anonymous_structs_unions {
class C {
struct { struct { struct { int a; }; }; };
public:
union { union { union { int b; }; }; };
static constexpr auto r_a = ^^a;
};
static_assert(is_accessible(C::r_a,
std::meta::access_context::unprivileged()));
static_assert(!is_accessible(C::r_a,
std::meta::access_context::unprivileged().via(^^C)));
static_assert(is_accessible(^^C::b,
std::meta::access_context::unprivileged()));
static_assert(is_accessible(^^C::b,
std::meta::access_context::unprivileged().via(^^C)));
static union { int a; };
static_assert(is_accessible(^^a,
std::meta::access_context::unprivileged()));
} // namespace anonymous_structs_unions
int main() { }