Sema::MergeFunctionDecl improperly checking for an out-of-line def of defaulted function

[CrisCristescu]

Summary

Sema::MergeFunctionDecl is improperly checking for an out-of-line definition of a function that is declared as =default in its class definition.

[rsmith]

LGTM

lib/Sema/SemaDecl.cpp

if (OldMethod && NewMethod) {
         if (isFriend) {
           NewMethod->setImplicit();
         } else {
           Diag(NewMethod->getLocation(),
                diag::err_definition_of_implicitly_declared_member)
             << New << getSpecialMember(OldMethod);
           return true;
         }
-      } else if (OldMethod->isExplicitlyDefaulted() && !isFriend) {
+      } else if (OldMethod->getFirstDecl()->isExplicitlyDefaulted() && !isFriend) {
         Diag(NewMethod->getLocation(),
              diag::err_definition_of_explicitly_defaulted_member)
           << getSpecialMember(OldMethod);
         return true;
       }
     }
 
     // C++11 [dcl.attr.noreturn]p1:

test/SemaCXX/cxx0x-defaulted-functions.cpp

namespace PR13527 {
   Y::Y() = default; // expected-error {{definition of explicitly defaulted}}
   Y::Y(const Y&) = default; // expected-error {{definition of explicitly defaulted}}
   Y::Y(Y&&) = default; // expected-error {{definition of explicitly defaulted}}
   Y &Y::operator=(const Y&) = default; // expected-error {{definition of explicitly defaulted}}
   Y &Y::operator=(Y&&) = default; // expected-error {{definition of explicitly defaulted}}
   Y::~Y() = default; // expected-error {{definition of explicitly defaulted}}
 }
 
+namespace PR27699 {
+  struct X {
+    X();
+  };
+  X::X() = default; // expected-note {{here}}
+  X::X() = default; // expected-error {{redefinition of 'X'}}
+}
+
 namespace PR14577 {
   template<typename T>
   struct Outer {
     template<typename U>
     struct Inner1 {
       ~Inner1();
     };