[Voted into the WP at the February, 2012 meeting; moved to DR at the October, 2012 meeting.]

Proposed resolution (August, 2011):

1. Change 9.5.2 [dcl.fct.def.default] paragraph 2 as follows:

...If a function is explicitly defaulted on its first declaration,

• ...

• in the case of a copy constructor, move constructor, copy assignment operator, or move assignment operator, it shall have the same parameter type as if it had been implicitly declared.

2. Change 11.4.5.3 [class.copy.ctor] paragraph 12 as follows:

A copy/move constructor for class X is trivial if it is not user-provided, its declared parameter type is the same as if it had been implicitly declared, and if...

3. Change 11.4.5.3 [class.copy.ctor] paragraph 25 as follows:

A copy/move assignment operator for class X is trivial if it is not user-provided, its declared parameter type is the same as if it had been implicitly declared, and if...

Paragraph 1 of 9.5.2 [dcl.fct.def.default] allows an explicitly-defaulted copy constructor or copy assignment operator to have a parameter type that is a reference to non-const, even if the corresponding implicitly-declared function would have a reference to const. However, paragraph 2 says that a copy constructor or copy assignment operator that is defaulted on its first declaration, the parameter type must be exactly the same. Is there a good reason for the stricter rule for a function that is defaulted on its first declaration?