[Sema] Add support for flexible array members in Obj-C.

[vsapsai]

Summary

Allow Obj-C ivars with incomplete array type but only as the last ivar.
Also add a requirement for ivars that contain a flexible array member to
be at the end of class too. It is possible to add in a subclass another
ivar at the end but we'll emit a warning in this case. Also we'll emit a
warning if a variable sized ivar is declared in class extension or in
implementation because subclasses won't know they should avoid adding
new ivars.

In ARC incomplete array objects are treated as __unsafe_unretained so
require them to be marked as such.

Prohibit synthesizing ivars with flexible array members because order of
synthesized ivars is not obvious and tricky to control. Spelling out
ivar explicitly gives control to developers and helps to avoid surprises
with unexpected ivar ordering.

For C and C++ changed diagnostic to tell explicitly a field is not the
last one and point to the next field. It is not as useful as in Obj-C
but it is an improvement and it is consistent with Obj-C. For C for
unions emit more specific err_flexible_array_union instead of generic
err_field_incomplete.

rdar://problem/21054495

[vsapsai]

Previous discussion on the mailing list can be found at http://lists.llvm.org/pipermail/cfe-dev/2017-September/055548.html The implementation is not exactly like it was discussed, it has some changes.

There is another case when extra ivar is added at the end, it is for bitfields. But bitfields aren't compatible with flexible array members so I decided not to include them in tests.

I separated CodeGen change in a separate patch that can be found here.

[rjmccall]

clang/include/clang/Basic/DiagnosticSemaKinds.td

5226

"Variable sized type" is a bit too close to the C99 variably-sized array type extension. Maybe "unbounded array type" if you're trying to cover both "int x[];" and "int x[0];"?

Well, I guess there's some precedent for using this terminology, but ugh.

clang/lib/Sema/SemaDecl.cpp

15046

"Whether" rather than "If", please. You should also leave a comment about *why* we can't check this here — I assume because you also want to complain about the last explicit ivar if there are synthesized ivars? I think we could at least still check this for @interface ivars.

[vsapsai]

clang/include/clang/Basic/DiagnosticSemaKinds.td

5226

I took "variable sized type" entirely from

def ext_variable_sized_type_in_struct : ExtWarn<
  "field %0 with variable sized type %1 not at the end of a struct or class is"
  " a GNU extension">, InGroup<GNUVariableSizedTypeNotAtEnd>;

I'm not covering int x[0];. All the changes are for int x[]; and struct { int x[]; }

clang/lib/Sema/SemaDecl.cpp

15046

Will change s/If/Whether/

Main reason for checking elsewhere is to check after ivars are synthesized, you are right. At some point I had this check done here but for detecting ivar-after-flexible-array on interface/extension, interface/implementation border I am relying on chained ObjCIvarDecl. But here I have ArrayRef<Decl *> Fields so implementation will be different. I decided that it would be cleaner to perform the check only in DiagnoseVariableSizedIvars.

[rjmccall]

clang/lib/Sema/SemaDecl.cpp

15046

Is there a reason to do any of the checking here, then?

[vsapsai]

clang/lib/Sema/SemaDecl.cpp

15046

No objective reason. I updated isIncompleteArrayType branch to avoid flexible array members rejected at line 15023

} else if (!FDTy->isDependentType() &&
           RequireCompleteType(FD->getLocation(), FD->getType(),
                               diag::err_field_incomplete)) {

and here I've added it for consistency. Will move to DiagnoseVariableSizedIvars and see if it works fine, don't expect any problems.

[vsapsai]

• Address rjmccall review comment, move warn_variable_sized_ivar_visibility to DiagnoseVariableSizedIvars.

[rjmccall]

LGTM.

clang/include/clang/Basic/DiagnosticGroups.td

 def ObjCDesignatedInit : DiagGroup<"objc-designated-initializers">;
 def ObjCRetainBlockProperty : DiagGroup<"objc-noncopy-retain-block-property">;
 def ObjCReadonlyPropertyHasSetter : DiagGroup<"objc-readonly-with-setter-property">;
 def ObjCInvalidIBOutletProperty : DiagGroup<"invalid-iboutlet">;
 def ObjCRootClass : DiagGroup<"objc-root-class">;
 def ObjCPointerIntrospectPerformSelector : DiagGroup<"deprecated-objc-pointer-introspection-performSelector">;
 def ObjCPointerIntrospect : DiagGroup<"deprecated-objc-pointer-introspection", [ObjCPointerIntrospectPerformSelector]>;
 def ObjCMultipleMethodNames : DiagGroup<"objc-multiple-method-names">;
+def ObjCFlexibleArray : DiagGroup<"objc-flexible-array">;
 def OpenCLUnsupportedRGBA: DiagGroup<"opencl-unsupported-rgba">;
 def DeprecatedObjCIsaUsage : DiagGroup<"deprecated-objc-isa-usage">;
 def ExplicitInitializeCall : DiagGroup<"explicit-initialize-call">;
 def Packed : DiagGroup<"packed">;
 def Padded : DiagGroup<"padded">;
 def PessimizingMove : DiagGroup<"pessimizing-move">;
 def PointerArith : DiagGroup<"pointer-arith">;
 def PoundWarning : DiagGroup<"#warnings">;
def Most : DiagGroup<"most", [
     StringPlusInt,
     Trigraphs,
     Uninitialized,
     UnknownPragmas,
     Unused,
     VolatileRegisterVar,
     ObjCMissingSuperCalls,
     ObjCDesignatedInit,
+    ObjCFlexibleArray,
     OverloadedVirtual,
     PrivateExtern,
     SelTypeCast,
     ExternCCompat,
     UserDefinedWarnings
  ]>;
 
 // Thread Safety warnings 

clang/include/clang/Basic/DiagnosticSemaKinds.td

def ext_flexible_array_union_ms : Extension<
   InGroup<MicrosoftFlexibleArray>;
 def ext_flexible_array_empty_aggregate_gnu : Extension<
   "flexible array member %0 in otherwise empty "
   "%select{struct|interface|union|class|enum}1 is a GNU extension">,
   InGroup<GNUEmptyStruct>;
 def ext_flexible_array_union_gnu : Extension<
   "flexible array member %0 in a union is a GNU extension">, InGroup<GNUFlexibleArrayUnionMember>;
 
+def err_flexible_array_not_at_end : Error<
+  "flexible array member %0 with type %1 is not at the end of"
+  " %select{struct|interface|union|class|enum}2">;
+def err_objc_variable_sized_type_not_at_end : Error<
+  "field %0 with variable sized type %1 is not at the end of class">;
+def note_next_field_declaration : Note<
+  "next field declaration is here">;
+def note_next_ivar_declaration : Note<
+  "next %select{instance variable declaration|synthesized instance variable}0"
+  " is here">;
+def err_synthesize_variable_sized_ivar : Error<
+  "synthesized property with variable size type %0"
+  " requires an existing instance variable">;
+def err_flexible_array_arc_retainable : Error<
+  "ARC forbids flexible array members with retainable object type">;
+def warn_variable_sized_ivar_visibility : Warning<
+  "field %0 with variable sized type %1 is not visible to subclasses and"
+  " can conflict with their instance variables">, InGroup<ObjCFlexibleArray>;
+def warn_superclass_variable_sized_type_not_at_end : Warning<
+  "field %0 can overwrite instance variable %1 with variable sized type %2"
+  " in superclass %3">, InGroup<ObjCFlexibleArray>;
+
 let CategoryName = "ARC Semantic Issue" in {
 
 // ARC-mode diagnostics.
 
 let CategoryName = "ARC Weak References" in {
 
 def err_arc_weak_no_runtime : Error<
   "cannot create __weak reference because the current deployment target "

clang/lib/Sema/SemaDecl.cpp

for (ArrayRef<Decl *>::iterator i = Fields.begin(), end = Fields.end();
     //   incomplete or function type (hence, a structure shall not
     //   contain an instance of itself, but may contain a pointer to
     //   an instance of itself), except that the last member of a
     //   structure with more than one named member may have incomplete
     //   array type; such a structure (and any union containing,
     //   possibly recursively, a member that is such a structure)
     //   shall not be a member of a structure or an element of an
     //   array.
+    bool IsLastField = (i + 1 == Fields.end());
     if (FDTy->isFunctionType()) {
       // Field declared as a function.
       Diag(FD->getLocation(), diag::err_field_declared_as_function)
         << FD->getDeclName();
       FD->setInvalidDecl();
       EnclosingDecl->setInvalidDecl();
       continue;
-    } else if (FDTy->isIncompleteArrayType() && Record &&
-               ((i + 1 == Fields.end() && !Record->isUnion()) ||
-                ((getLangOpts().MicrosoftExt ||
-                  getLangOpts().CPlusPlus) &&
-                 (i + 1 == Fields.end() || Record->isUnion())))) {
+    } else if (FDTy->isIncompleteArrayType() &&
+               (Record || isa<ObjCContainerDecl>(EnclosingDecl))) {
+      if (Record) {
         // Flexible array member.
         // Microsoft and g++ is more permissive regarding flexible array.
         // It will accept flexible array in union and also
         // as the sole element of a struct/class.
         unsigned DiagID = 0;
-      if (Record->isUnion())
+        if (!Record->isUnion() && !IsLastField) {
+          Diag(FD->getLocation(), diag::err_flexible_array_not_at_end)
+            << FD->getDeclName() << FD->getType() << Record->getTagKind();
+          Diag((*(i + 1))->getLocation(), diag::note_next_field_declaration);
+          FD->setInvalidDecl();
+          EnclosingDecl->setInvalidDecl();
+          continue;
+        } else if (Record->isUnion())
           DiagID = getLangOpts().MicrosoftExt
                        ? diag::ext_flexible_array_union_ms
                        : getLangOpts().CPlusPlus
                              ? diag::ext_flexible_array_union_gnu
                              : diag::err_flexible_array_union;
         else if (NumNamedMembers < 1)
           DiagID = getLangOpts().MicrosoftExt
                        ? diag::ext_flexible_array_empty_aggregate_ms
                        : getLangOpts().CPlusPlus
                              ? diag::ext_flexible_array_empty_aggregate_gnu
                              : diag::err_flexible_array_empty_aggregate;
 
         if (DiagID)
           Diag(FD->getLocation(), DiagID) << FD->getDeclName()
                                           << Record->getTagKind();
         // While the layout of types that contain virtual bases is not specified
         // by the C++ standard, both the Itanium and Microsoft C++ ABIs place
         // virtual bases after the derived members.  This would make a flexible
         // array member declared at the end of an object not adjacent to the end
         // of the type.
         if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Record))
           if (RD->getNumVBases() != 0)
             Diag(FD->getLocation(), diag::err_flexible_array_virtual_base)
               << FD->getDeclName() << Record->getTagKind();
         if (!getLangOpts().C99)
           Diag(FD->getLocation(), diag::ext_c99_flexible_array_member)
             << FD->getDeclName() << Record->getTagKind();
 
         // If the element type has a non-trivial destructor, we would not
         // implicitly destroy the elements, so disallow it for now.
         //
         // FIXME: GCC allows this. We should probably either implicitly delete
         // the destructor of the containing class, or just allow this.
         QualType BaseElem = Context.getBaseElementType(FD->getType());
         if (!BaseElem->isDependentType() && BaseElem.isDestructedType()) {
           Diag(FD->getLocation(), diag::err_flexible_array_has_nontrivial_dtor)
             << FD->getDeclName() << FD->getType();
           FD->setInvalidDecl();
           EnclosingDecl->setInvalidDecl();
           continue;
         }
         // Okay, we have a legal flexible array member at the end of the struct.
         Record->setHasFlexibleArrayMember(true);
+      } else {
+        // In ObjCContainerDecl ivars with incomplete array type are accepted,
+        // unless they are followed by another ivar. That check is done
+        // elsewhere, after synthesized ivars are known.
+      }
     } else if (!FDTy->isDependentType() &&
                RequireCompleteType(FD->getLocation(), FD->getType(),
                                    diag::err_field_incomplete)) {
       // Incomplete type
       FD->setInvalidDecl();
       EnclosingDecl->setInvalidDecl();
       continue;
     } else if (const RecordType *FDTTy = FDTy->getAs<RecordType>()) {
       if (Record && FDTTy->getDecl()->hasFlexibleArrayMember()) {
         // A type which contains a flexible array member is considered to be a
         // flexible array member.
         Record->setHasFlexibleArrayMember(true);
         if (!Record->isUnion()) {
           // If this is a struct/class and this is not the last element, reject
           // it.  Note that GCC supports variable sized arrays in the middle of
           // structures.
-          if (i + 1 != Fields.end())
+          if (!IsLastField)
             Diag(FD->getLocation(), diag::ext_variable_sized_type_in_struct)
               << FD->getDeclName() << FD->getType();
           else {
             // We support flexible arrays at the end of structs in
             // other structs as an extension.
             Diag(FD->getLocation(), diag::ext_flexible_array_in_struct)
               << FD->getDeclName();
           }
         }
       }
       if (isa<ObjCContainerDecl>(EnclosingDecl) &&
           RequireNonAbstractType(FD->getLocation(), FD->getType(),
                                  diag::err_abstract_type_in_decl,
                                  AbstractIvarType)) {
         // Ivars can not have abstract class types
         FD->setInvalidDecl();
       }

clang/lib/Sema/SemaDeclObjC.cpp

if (ivar->getType().getObjCLifetime() == Qualifiers::OCL_Weak) {
         S.Diag(ivar->getLocation(), diag::err_arc_weak_disabled);
       } else {
         S.Diag(ivar->getLocation(), diag::err_arc_weak_no_runtime);
       }
     }
   }
 }
 
+/// Diagnose attempts to use flexible array member with retainable object type.
+static void DiagnoseRetainableFlexibleArrayMember(Sema &S,
+                                                  ObjCInterfaceDecl *ID) {
+  if (!S.getLangOpts().ObjCAutoRefCount)
+    return;
+
+  for (auto ivar = ID->all_declared_ivar_begin(); ivar;
+       ivar = ivar->getNextIvar()) {
+    if (ivar->isInvalidDecl())
+      continue;
+    QualType IvarTy = ivar->getType();
+    if (IvarTy->isIncompleteArrayType() &&
+        (IvarTy.getObjCLifetime() != Qualifiers::OCL_ExplicitNone) &&
+        IvarTy->isObjCLifetimeType()) {
+      S.Diag(ivar->getLocation(), diag::err_flexible_array_arc_retainable);
+      ivar->setInvalidDecl();
+    }
+  }
+}
+
 Sema::ObjCContainerKind Sema::getObjCContainerKind() const {
   switch (CurContext->getDeclKind()) {
     case Decl::ObjCInterface:
       return Sema::OCK_Interface;
     case Decl::ObjCProtocol:
       return Sema::OCK_Protocol;
     case Decl::ObjCCategory:
       if (cast<ObjCCategoryDecl>(CurContext)->IsClassExtension())
         return Sema::OCK_ClassExtension;
       return Sema::OCK_Category;
     case Decl::ObjCImplementation:
       return Sema::OCK_Implementation;
     case Decl::ObjCCategoryImpl:
       return Sema::OCK_CategoryImplementation;
 
     default:
       return Sema::OCK_None;
   }
 }
 
+static bool IsVariableSizedType(QualType T) {
+  if (T->isIncompleteArrayType())
+    return true;
+  const auto *RecordTy = T->getAs<RecordType>();
+  return (RecordTy && RecordTy->getDecl()->hasFlexibleArrayMember());
+}
+
+static void DiagnoseVariableSizedIvars(Sema &S, ObjCContainerDecl *OCD) {
+  ObjCInterfaceDecl *IntfDecl = nullptr;
+  ObjCInterfaceDecl::ivar_range Ivars = llvm::make_range(
+      ObjCInterfaceDecl::ivar_iterator(), ObjCInterfaceDecl::ivar_iterator());
+  if ((IntfDecl = dyn_cast<ObjCInterfaceDecl>(OCD))) {
+    Ivars = IntfDecl->ivars();
+  } else if (auto *ImplDecl = dyn_cast<ObjCImplementationDecl>(OCD)) {
+    IntfDecl = ImplDecl->getClassInterface();
+    Ivars = ImplDecl->ivars();
+  } else if (auto *CategoryDecl = dyn_cast<ObjCCategoryDecl>(OCD)) {
+    if (CategoryDecl->IsClassExtension()) {
+      IntfDecl = CategoryDecl->getClassInterface();
+      Ivars = CategoryDecl->ivars();
+    }
+  }
+
+  // Check if variable sized ivar is in interface and visible to subclasses.
+  if (!isa<ObjCInterfaceDecl>(OCD)) {
+    for (auto ivar : Ivars) {
+      if (!ivar->isInvalidDecl() && IsVariableSizedType(ivar->getType())) {
+        S.Diag(ivar->getLocation(), diag::warn_variable_sized_ivar_visibility)
+            << ivar->getDeclName() << ivar->getType();
+      }
+    }
+  }
+
+  // Subsequent checks require interface decl.
+  if (!IntfDecl)
+    return;
+
+  // Check if variable sized ivar is followed by another ivar.
+  for (ObjCIvarDecl *ivar = IntfDecl->all_declared_ivar_begin(); ivar;
+       ivar = ivar->getNextIvar()) {
+    if (ivar->isInvalidDecl() || !ivar->getNextIvar())
+      continue;
+    QualType IvarTy = ivar->getType();
+    bool IsInvalidIvar = false;
+    if (IvarTy->isIncompleteArrayType()) {
+      S.Diag(ivar->getLocation(), diag::err_flexible_array_not_at_end)
+          << ivar->getDeclName() << IvarTy
+          << TTK_Class; // Use "class" for Obj-C.
+      IsInvalidIvar = true;
+    } else if (const RecordType *RecordTy = IvarTy->getAs<RecordType>()) {
+      if (RecordTy->getDecl()->hasFlexibleArrayMember()) {
+        S.Diag(ivar->getLocation(),
+               diag::err_objc_variable_sized_type_not_at_end)
+            << ivar->getDeclName() << IvarTy;
+        IsInvalidIvar = true;
+      }
+    }
+    if (IsInvalidIvar) {
+      S.Diag(ivar->getNextIvar()->getLocation(),
+             diag::note_next_ivar_declaration)
+          << ivar->getNextIvar()->getSynthesize();
+      ivar->setInvalidDecl();
+    }
+  }
+
+  // Check if ObjC container adds ivars after variable sized ivar in superclass.
+  // Perform the check only if OCD is the first container to declare ivars to
+  // avoid multiple warnings for the same ivar.
+  ObjCIvarDecl *FirstIvar =
+      (Ivars.begin() == Ivars.end()) ? nullptr : *Ivars.begin();
+  if (FirstIvar && (FirstIvar == IntfDecl->all_declared_ivar_begin())) {
+    const ObjCInterfaceDecl *SuperClass = IntfDecl->getSuperClass();
+    while (SuperClass && SuperClass->ivar_empty())
+      SuperClass = SuperClass->getSuperClass();
+    if (SuperClass) {
+      auto IvarIter = SuperClass->ivar_begin();
+      std::advance(IvarIter, SuperClass->ivar_size() - 1);
+      const ObjCIvarDecl *LastIvar = *IvarIter;
+      if (IsVariableSizedType(LastIvar->getType())) {
+        S.Diag(FirstIvar->getLocation(),
+               diag::warn_superclass_variable_sized_type_not_at_end)
+            << FirstIvar->getDeclName() << LastIvar->getDeclName()
+            << LastIvar->getType() << SuperClass->getDeclName();
+        S.Diag(LastIvar->getLocation(), diag::note_entity_declared_at)
+            << LastIvar->getDeclName();
+      }
+    }
+  }
+}
+
 // Note: For class/category implementations, allMethods is always null.
 Decl *Sema::ActOnAtEnd(Scope *S, SourceRange AtEnd, ArrayRef<Decl *> allMethods,
                        ArrayRef<DeclGroupPtrTy> allTUVars) {
   if (getObjCContainerKind() == Sema::OCK_None)
     return nullptr;
 
   assert(AtEnd.isValid() && "Invalid location for '@end'");
 
if (ObjCInterfaceDecl* IDecl = IC->getClassInterface()) {
       }
       ImplMethodsVsClassMethods(S, IC, IDecl);
       AtomicPropertySetterGetterRules(IC, IDecl);
       DiagnoseOwningPropertyGetterSynthesis(IC);
       DiagnoseUnusedBackingIvarInAccessor(S, IC);
       if (IDecl->hasDesignatedInitializers())
         DiagnoseMissingDesignatedInitOverrides(IC, IDecl);
       DiagnoseWeakIvars(*this, IC);
+      DiagnoseRetainableFlexibleArrayMember(*this, IDecl);
 
       bool HasRootClassAttr = IDecl->hasAttr<ObjCRootClassAttr>();
       if (IDecl->getSuperClass() == nullptr) {
         // This class has no superclass, so check that it has been marked with
         // __attribute((objc_root_class)).
         if (!HasRootClassAttr) {
           SourceLocation DeclLoc(IDecl->getLocation());
           SourceLocation SuperClassLoc(getLocForEndOfToken(DeclLoc));
if (ObjCImplementationDecl *IC=dyn_cast<ObjCImplementationDecl>(ClassDecl)) {
     if (const ObjCInterfaceDecl *Super = IntfDecl->getSuperClass()) {
       if (!IntfDecl->hasAttr<ObjCSubclassingRestrictedAttr>() &&
           Super->hasAttr<ObjCSubclassingRestrictedAttr>()) {
         Diag(IntfDecl->getLocation(), diag::err_restricted_superclass_mismatch);
         Diag(Super->getLocation(), diag::note_class_declared);
       }
     }
   }
+  DiagnoseVariableSizedIvars(*this, OCD);
   if (isInterfaceDeclKind) {
     // Reject invalid vardecls.
     for (unsigned i = 0, e = allTUVars.size(); i != e; i++) {
       DeclGroupRef DG = allTUVars[i].get();
       for (DeclGroupRef::iterator I = DG.begin(), E = DG.end(); I != E; ++I)
         if (VarDecl *VDecl = dyn_cast<VarDecl>(*I)) {
           if (!VDecl->hasExternalStorage())
             Diag(VDecl->getLocation(), diag::err_objc_var_decl_inclass);

clang/lib/Sema/SemaObjCProperty.cpp

if (!Ivar) {
       if (RequireNonAbstractType(PropertyIvarLoc,
                                  PropertyIvarType,
                                  diag::err_abstract_type_in_decl,
                                  AbstractSynthesizedIvarType)) {
         Diag(property->getLocation(), diag::note_property_declare);
         // An abstract type is as bad as an incomplete type.
         CompleteTypeErr = true;
       }
+      if (!CompleteTypeErr) {
+        const RecordType *RecordTy = PropertyIvarType->getAs<RecordType>();
+        if (RecordTy && RecordTy->getDecl()->hasFlexibleArrayMember()) {
+          Diag(PropertyIvarLoc, diag::err_synthesize_variable_sized_ivar)
+            << PropertyIvarType;
+          CompleteTypeErr = true; // suppress later diagnostics about the ivar
+        }
+      }
       if (CompleteTypeErr)
         Ivar->setInvalidDecl();
       ClassImpDecl->addDecl(Ivar);
       IDecl->makeDeclVisibleInContext(Ivar);
 
       if (getLangOpts().ObjCRuntime.isFragile())
         Diag(PropertyDiagLoc, diag::err_missing_property_ivar_decl)
             << PropertyId;

clang/test/Sema/transparent-union.c

union pr15134v2 {
   };
   struct {  // expected-warning {{alignment of field '' (64 bits) does not match the alignment of the first field in transparent union; transparent_union attribute ignored}}
     unsigned int u3;
   } __attribute__((aligned(8)));
 } __attribute__((transparent_union));
 
 union pr30520v { void b; } __attribute__((transparent_union)); // expected-error {{field has incomplete type 'void'}}
 
-union pr30520a { int b[]; } __attribute__((transparent_union)); // expected-error {{field has incomplete type 'int []'}}
+union pr30520a { int b[]; } __attribute__((transparent_union)); // expected-error {{flexible array member 'b' in a union is not allowed}}
 
 // expected-note@+1 2 {{forward declaration of 'struct stb'}}
 union pr30520s { struct stb b; } __attribute__((transparent_union)); // expected-error {{field has incomplete type 'struct stb'}}
 
 union pr30520s2 { int *v; struct stb b; } __attribute__((transparent_union)); // expected-error {{field has incomplete type 'struct stb'}}
 
 typedef union __attribute__((__transparent_union__)) {
   int *i;

clang/test/SemaCXX/flexible-array-test.cpp

class A {
   char c[];
 };
 
 union B {
   int s;
   char c[];
 };
 
+class C {
+  char c[]; // expected-error {{flexible array member 'c' with type 'char []' is not at the end of class}}
+  int s; // expected-note {{next field declaration is here}}
+};
+
 namespace rdar9065507 {
 
 struct StorageBase {
   long ref_count;
   unsigned size;
   unsigned capacity;
 };
 

clang/test/SemaObjC/flexible-array-arc.m

+// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -verify -Wno-objc-root-class %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-objc-root-class -DNOARC %s
+#ifdef NOARC
+// expected-no-diagnostics
+#endif
+
+@interface RetainableArray {
+  id flexible[];
+#ifndef NOARC
+  // expected-error@-2 {{ARC forbids flexible array members with retainable object type}}
+#endif
+}
+@end
+@implementation RetainableArray
+@end
+
+// Emit diagnostic only if have @implementation.
+@interface RetainableArrayWithoutImpl {
+  id flexible[];
+}
+@end
+
+// With ARC flexible array member objects can be only __unsafe_unretained
+@interface UnsafeUnretainedArray {
+  __unsafe_unretained id flexible[];
+}
+@end
+@implementation UnsafeUnretainedArray
+@end
+
+@interface NotObjCLifetimeTypeArray {
+  char flexible[];
+}
+@end
+@implementation NotObjCLifetimeTypeArray
+@end

clang/test/SemaObjC/flexible-array.m

+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-objc-root-class %s
+
+// # Flexible array member.
+// ## Instance variables only in interface.
+@interface LastIvar {
+  char flexible[];
+}
+@end
+
+@interface NotLastIvar {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+// ## Instance variables in implementation.
+@interface LastIvarInImpl
+@end
+@implementation LastIvarInImpl {
+  char flexible[]; // expected-warning {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+}
+@end
+
+@interface NotLastIvarInImpl
+@end
+@implementation NotLastIvarInImpl {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+  // expected-warning@-1 {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+@implementation NotLastIvarInImplWithoutInterface { // expected-warning {{cannot find interface declaration for 'NotLastIvarInImplWithoutInterface'}}
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+  // expected-warning@-1 {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+@interface LastIvarInClass_OtherIvarInImpl {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+}
+@end
+@implementation LastIvarInClass_OtherIvarInImpl {
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+// ## Non-instance variables in implementation.
+@interface LastIvarInClass_UnrelatedVarInImpl {
+  char flexible[];
+}
+@end
+@implementation LastIvarInClass_UnrelatedVarInImpl
+int nonIvar;
+@end
+
+// ## Instance variables in class extension.
+@interface LastIvarInExtension
+@end
+@interface LastIvarInExtension() {
+  char flexible[]; // expected-warning {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+}
+@end
+
+@interface NotLastIvarInExtension
+@end
+@interface NotLastIvarInExtension() {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+  // expected-warning@-1 {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+@interface LastIvarInClass_OtherIvarInExtension {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+}
+@end
+@interface LastIvarInClass_OtherIvarInExtension() {
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+@interface LastIvarInExtension_OtherIvarInExtension
+@end
+@interface LastIvarInExtension_OtherIvarInExtension() {
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+@interface LastIvarInExtension_OtherIvarInExtension()
+// Extension without ivars to test we see through such extensions.
+@end
+@interface LastIvarInExtension_OtherIvarInExtension() {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+  // expected-warning@-1 {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+}
+@end
+
+@interface LastIvarInExtension_OtherIvarInImpl
+@end
+@interface LastIvarInExtension_OtherIvarInImpl() {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+  // expected-warning@-1 {{field 'flexible' with variable sized type 'char []' is not visible to subclasses and can conflict with their instance variables}}
+}
+@end
+@implementation LastIvarInExtension_OtherIvarInImpl {
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+// ## Instance variables in named categories.
+@interface IvarInNamedCategory
+@end
+@interface IvarInNamedCategory(Category) {
+  char flexible[]; // expected-error {{instance variables may not be placed in categories}}
+}
+@end
+
+// ## Synthesized instance variable.
+@interface LastIvarAndProperty {
+  char _flexible[];
+}
+@property char flexible[]; // expected-error {{property cannot have array or function type 'char []'}}
+@end
+
+// ## Synthesize other instance variables.
+@interface LastIvar_ExplicitlyNamedPropertyBackingIvarPreceding {
+  int _elementsCount;
+  char flexible[];
+}
+@property int count;
+@end
+@implementation LastIvar_ExplicitlyNamedPropertyBackingIvarPreceding
+@synthesize count = _elementsCount;
+@end
+
+@interface LastIvar_ImplicitlyNamedPropertyBackingIvarPreceding {
+  int count;
+  char flexible[];
+}
+@property int count;
+@end
+@implementation LastIvar_ImplicitlyNamedPropertyBackingIvarPreceding
+@synthesize count;
+@end
+
+@interface NotLastIvar_ExplicitlyNamedPropertyBackingIvarLast {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+}
+@property int count;
+@end
+@implementation NotLastIvar_ExplicitlyNamedPropertyBackingIvarLast
+@synthesize count = _elementsCount; // expected-note {{next synthesized instance variable is here}}
+@end
+
+@interface NotLastIvar_ImplicitlyNamedPropertyBackingIvarLast {
+  char flexible[]; // expected-error {{flexible array member 'flexible' with type 'char []' is not at the end of class}}
+}
+@property int count; // expected-note {{next synthesized instance variable is here}}
+@end
+@implementation NotLastIvar_ImplicitlyNamedPropertyBackingIvarLast
+// Test auto-synthesize.
+//@synthesize count;
+@end
+
+
+// # Variable sized types.
+struct Packet {
+  unsigned int size;
+  char data[];
+};
+
+// ## Instance variables only in interface.
+@interface LastStructIvar {
+  struct Packet flexible;
+}
+@end
+
+@interface NotLastStructIvar {
+  struct Packet flexible; // expected-error {{field 'flexible' with variable sized type 'struct Packet' is not at the end of class}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+// ## Instance variables in implementation.
+@interface LastStructIvarInImpl
+@end
+@implementation LastStructIvarInImpl {
+  struct Packet flexible; // expected-warning {{field 'flexible' with variable sized type 'struct Packet' is not visible to subclasses and can conflict with their instance variables}}
+}
+@end
+
+@interface NotLastStructIvarInImpl
+@end
+@implementation NotLastStructIvarInImpl {
+  struct Packet flexible; // expected-error {{field 'flexible' with variable sized type 'struct Packet' is not at the end of class}}
+  // expected-warning@-1 {{field 'flexible' with variable sized type 'struct Packet' is not visible to subclasses and can conflict with their instance variables}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+@interface LastStructIvarInClass_OtherIvarInImpl {
+  struct Packet flexible; // expected-error {{field 'flexible' with variable sized type 'struct Packet' is not at the end of class}}
+}
+@end
+@implementation LastStructIvarInClass_OtherIvarInImpl {
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+// ## Synthesized instance variable.
+@interface LastSynthesizeStructIvar
+@property int first;
+@property struct Packet flexible; // expected-error {{synthesized property with variable size type 'struct Packet' requires an existing instance variable}}
+@end
+@implementation LastSynthesizeStructIvar
+@end
+
+@interface NotLastSynthesizeStructIvar
+@property struct Packet flexible; // expected-error {{synthesized property with variable size type 'struct Packet' requires an existing instance variable}}
+@property int last;
+@end
+@implementation NotLastSynthesizeStructIvar
+@end
+
+@interface LastStructIvarWithExistingIvarAndSynthesizedProperty {
+  struct Packet _flexible;
+}
+@property struct Packet flexible;
+@end
+@implementation LastStructIvarWithExistingIvarAndSynthesizedProperty
+@end
+
+
+// # Subclasses.
+@interface FlexibleArrayMemberBase {
+  char flexible[]; // expected-note6 {{'flexible' declared here}}
+}
+@end
+
+@interface NoIvarAdditions : FlexibleArrayMemberBase
+@end
+@implementation NoIvarAdditions
+@end
+
+@interface AddedIvarInInterface : FlexibleArrayMemberBase {
+  int last; // expected-warning {{field 'last' can overwrite instance variable 'flexible' with variable sized type 'char []' in superclass 'FlexibleArrayMemberBase'}}
+}
+@end
+
+@interface AddedIvarInImplementation : FlexibleArrayMemberBase
+@end
+@implementation AddedIvarInImplementation {
+  int last; // expected-warning {{field 'last' can overwrite instance variable 'flexible' with variable sized type 'char []' in superclass 'FlexibleArrayMemberBase'}}
+}
+@end
+
+@interface AddedIvarInExtension : FlexibleArrayMemberBase
+@end
+@interface AddedIvarInExtension() {
+  int last; // expected-warning {{field 'last' can overwrite instance variable 'flexible' with variable sized type 'char []' in superclass 'FlexibleArrayMemberBase'}}
+}
+@end
+
+@interface SynthesizedIvar : FlexibleArrayMemberBase
+@property int count;
+@end
+@implementation SynthesizedIvar
+@synthesize count; // expected-warning {{field 'count' can overwrite instance variable 'flexible' with variable sized type 'char []' in superclass 'FlexibleArrayMemberBase'}}
+@end
+
+@interface WarnInSubclassOnlyOnce : FlexibleArrayMemberBase {
+  int last; // expected-warning {{field 'last' can overwrite instance variable 'flexible' with variable sized type 'char []' in superclass 'FlexibleArrayMemberBase'}}
+}
+@end
+@interface WarnInSubclassOnlyOnce() {
+  int laster;
+}
+@end
+@implementation WarnInSubclassOnlyOnce {
+  int lastest;
+}
+@end
+
+@interface AddedIvarInSubSubClass : NoIvarAdditions {
+  int last; // expected-warning {{field 'last' can overwrite instance variable 'flexible' with variable sized type 'char []' in superclass 'FlexibleArrayMemberBase'}}
+}
+@end

clang/test/SemaObjC/ivar-sem-check-1.m

 // RUN: %clang_cc1 -fsyntax-only -verify %s
 
 struct S; // expected-note{{forward declaration of 'struct S'}}
 typedef int FOO();
 
 @interface INTF
 {
   struct F {} JJ;
-  int arr[];  // expected-error {{field has incomplete type}}
+  int arr[];  // expected-error {{flexible array member 'arr' with type 'int []' is not at the end of class}}
   struct S IC;  // expected-error {{field has incomplete type}}
+                // expected-note@-1 {{next instance variable declaration is here}}
   struct T { // expected-note {{previous definition is here}}
     struct T {} X;  // expected-error {{nested redefinition of 'T'}}
   }YYY; 
   FOO    BADFUNC;  // expected-error {{field 'BADFUNC' declared as a function}}
   int kaka; // expected-note {{previous declaration is here}}
   int kaka; // expected-error {{duplicate member 'kaka'}}
-  char ch[];  // expected-error {{field has incomplete type}}
+  char ch[];
 }
 @end

clang/test/SemaObjCXX/flexible-array.mm

+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-objc-root-class %s
+
+// Test only flexible array member functionality specific to C++.
+
+union VariableSizeUnion {
+  int s;
+  char c[];
+};
+
+@interface LastUnionIvar {
+  VariableSizeUnion flexible;
+}
+@end
+
+@interface NotLastUnionIvar {
+  VariableSizeUnion flexible; // expected-error {{field 'flexible' with variable sized type 'VariableSizeUnion' is not at the end of class}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end
+
+
+class VariableSizeClass {
+public:
+  int s;
+  char c[];
+};
+
+@interface LastClassIvar {
+  VariableSizeClass flexible;
+}
+@end
+
+@interface NotLastClassIvar {
+  VariableSizeClass flexible; // expected-error {{field 'flexible' with variable sized type 'VariableSizeClass' is not at the end of class}}
+  int last; // expected-note {{next instance variable declaration is here}}
+}
+@end