Fix rejects-valid caused by r261297.

r261297 called hasUserProvidedDefaultConstructor() to check if defining a
const object is ok.  This is incorrect for this example:

  struct X { template<typename ...T> X(T...); int n; };
  const X x; // formerly OK, now bogus error

Instead, track if a class has a defaulted default constructor, and disallow
a const object for classes that either have defaulted default constructors or
if they need an implicit constructor.

Bug report and fix approach by Richard Smith, thanks!

llvm-svn: 261770

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 1d1c99874b6..a88ab5fb5f2 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -5558,6 +5558,7 @@ void ASTWriter::AddCXXDefinitionData(const CXXRecordDecl *D, RecordDataImpl &Rec
   Record.push_back(Data.DeclaredNonTrivialSpecialMembers);
   Record.push_back(Data.HasIrrelevantDestructor);
   Record.push_back(Data.HasConstexprNonCopyMoveConstructor);
+  Record.push_back(Data.HasDefaultedDefaultConstructor);
   Record.push_back(Data.DefaultedDefaultConstructorIsConstexpr);
   Record.push_back(Data.HasConstexprDefaultConstructor);
   Record.push_back(Data.HasNonLiteralTypeFieldsOrBases);