r270353 - [AST] Cleanup comments regarding CXXRecordDecl::isEmpty

[David Majnemer via cfe-commits]

Author: majnemer
Date: Sun May 22 00:34:26 2016
New Revision: 270353

URL: http://llvm.org/viewvc/llvm-project?rev=270353&view=rev
Log:
[AST] Cleanup comments regarding CXXRecordDecl::isEmpty

We were missing references to the standard, some of our home-grown
verbiage didn't make any sense.

No functional change is intended.

Modified:
    cfe/trunk/include/clang/AST/DeclCXX.h
    cfe/trunk/lib/AST/DeclCXX.cpp

Modified: cfe/trunk/include/clang/AST/DeclCXX.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/AST/DeclCXX.h?rev=270353&r1=270352&r2=270353&view=diff
==============================================================================
--- cfe/trunk/include/clang/AST/DeclCXX.h (original)
+++ cfe/trunk/include/clang/AST/DeclCXX.h Sun May 22 00:34:26 2016
@@ -1139,9 +1139,10 @@ public:
   /// \brief Determine whether this is an empty class in the sense of
   /// (C++11 [meta.unary.prop]).
   ///
-  /// A non-union class is empty iff it has a virtual function, virtual base,
-  /// data member (other than 0-width bit-field) or inherits from a non-empty
-  /// class.
+  /// The CXXRecordDecl is a class type, but not a union type,
+  /// with no non-static data members other than bit-fields of length 0,
+  /// no virtual member functions, no virtual base classes,
+  /// and no base class B for which is_empty<B>::value is false.
   ///
   /// \note This does NOT include a check for union-ness.
   bool isEmpty() const { return data().Empty; }

Modified: cfe/trunk/lib/AST/DeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/DeclCXX.cpp?rev=270353&r1=270352&r2=270353&view=diff
==============================================================================
--- cfe/trunk/lib/AST/DeclCXX.cpp (original)
+++ cfe/trunk/lib/AST/DeclCXX.cpp Sun May 22 00:34:26 2016
@@ -172,8 +172,6 @@ CXXRecordDecl::setBases(CXXBaseSpecifier
     CXXRecordDecl *BaseClassDecl
       = cast<CXXRecordDecl>(BaseType->getAs<RecordType>()->getDecl());
 
-    // A class with a non-empty base class is not empty.
-    // FIXME: Standard ref?
     if (!BaseClassDecl->isEmpty()) {
       if (!data().Empty) {
         // C++0x [class]p7:
@@ -187,6 +185,9 @@ CXXRecordDecl::setBases(CXXBaseSpecifier
         data().IsStandardLayout = false;
       }
 
+      // C++14 [meta.unary.prop]p4:
+      //   T is a class type [...] with [...] no base class B for which
+      //   is_empty<B>::value is false.
       data().Empty = false;
       data().HasNoNonEmptyBases = false;
     }
@@ -238,9 +239,9 @@ CXXRecordDecl::setBases(CXXBaseSpecifier
       if (SeenVBaseTypes.insert(C.getCanonicalType(BaseType)).second)
         VBases.push_back(Base);
 
-      // C++11 [meta.unary.prop] is_empty:
-      //    T is a class type, but not a union type, with ... no virtual base
-      //    classes
+      // C++14 [meta.unary.prop] is_empty:
+      //   T is a class type, but not a union type, with ... no virtual base
+      //   classes
       data().Empty = false;
 
       // C++1z [dcl.init.agg]p1:
@@ -458,8 +459,8 @@ void CXXRecordDecl::addedMember(Decl *D)
       //   A POD-struct is an aggregate class...
       data().PlainOldData = false;
       
-      // Virtual functions make the class non-empty.
-      // FIXME: Standard ref?
+      // C++14 [meta.unary.prop]p4:
+      //   T is a class type [...] with [...] no virtual member functions...
       data().Empty = false;
 
       // C++ [class.virtual]p1:
@@ -938,7 +939,9 @@ void CXXRecordDecl::addedMember(Decl *D)
     if (!data().HasNoNonEmptyBases)
       data().IsStandardLayout = false;
 
-    // If this is not a zero-length bit-field, then the class is not empty.
+    // C++14 [meta.unary.prop]p4:
+    //   T is a class type [...] with [...] no non-static data members other
+    //   than bit-fields of length 0...
     if (data().Empty) {
       if (!Field->isBitField() ||
           (!Field->getBitWidth()->isTypeDependent() &&