[cfe-commits] r150157 - in /cfe/trunk: lib/Sema/SemaDeclCXX.cpp test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp

[Richard Smith]

Author: rsmith
Date: Thu Feb  9 00:40:58 2012
New Revision: 150157

URL: http://llvm.org/viewvc/llvm-project?rev=150157&view=rev
Log:
DR1359: A constexpr constructor does not need to initialize an empty struct or
empty union. This still rejects anonymous member structs or unions which only
contain such empty class types, pending standard wording defining exactly what
an empty class type is.

Modified:
    cfe/trunk/lib/Sema/SemaDeclCXX.cpp
    cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp

Modified: cfe/trunk/lib/Sema/SemaDeclCXX.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaDeclCXX.cpp?rev=150157&r1=150156&r2=150157&view=diff
==============================================================================
--- cfe/trunk/lib/Sema/SemaDeclCXX.cpp (original)
+++ cfe/trunk/lib/Sema/SemaDeclCXX.cpp Thu Feb  9 00:40:58 2012
@@ -815,7 +815,11 @@
                                           bool &Diagnosed) {
   if (Field->isUnnamedBitfield())
     return;
-  
+
+  if (Field->isAnonymousStructOrUnion() &&
+      Field->getType()->getAsCXXRecordDecl()->isEmpty())
+    return;
+
   if (!Inits.count(Field)) {
     if (!Diagnosed) {
       SemaRef.Diag(Dcl->getLocation(), diag::err_constexpr_ctor_missing_init);
@@ -901,11 +905,14 @@
   if (const CXXConstructorDecl *Constructor
         = dyn_cast<CXXConstructorDecl>(Dcl)) {
     const CXXRecordDecl *RD = Constructor->getParent();
-    // - every non-static data member and base class sub-object shall be
-    //   initialized;
+    // DR1359:
+    // - every non-variant non-static data member and base class sub-object
+    //   shall be initialized;
+    // - if the class is a non-empty union, or for each non-empty anonymous
+    //   union member of a non-union class, exactly one non-static data member
+    //   shall be initialized;
     if (RD->isUnion()) {
-      // DR1359: Exactly one member of a union shall be initialized.
-      if (Constructor->getNumCtorInitializers() == 0) {
+      if (Constructor->getNumCtorInitializers() == 0 && !RD->isEmpty()) {
         Diag(Dcl->getLocation(), diag::err_constexpr_union_ctor_no_init);
         return false;
       }

Modified: cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp?rev=150157&r1=150156&r2=150157&view=diff
==============================================================================
--- cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp (original)
+++ cfe/trunk/test/CXX/dcl.dcl/dcl.spec/dcl.constexpr/p4.cpp Thu Feb  9 00:40:58 2012
@@ -151,6 +151,16 @@
   constexpr AnonMembers(int(&)[6]) {} // expected-error {{constexpr constructor must initialize all members}}
 };
 
+union Empty {
+  constexpr Empty() {} // ok
+} constexpr empty1;
+
+struct EmptyVariant {
+  union {};
+  struct {};
+  constexpr EmptyVariant() {} // ok
+} constexpr empty2;
+
 template<typename T> using Int = int;
 template<typename T>
 struct TemplateInit {