Proposed resolution:

This wording is relative to N4762.

1. Modify [fs.path.concat] as indicated:

   path& operator+=(const path& x);
   path& operator+=(const string_type& x);
   path& operator+=(basic_string_view<value_type> x);
   path& operator+=(const value_type* x);
   path& operator+=(value_type x);
   template<class Source>
     path& operator+=(const Source& x);
   template<class EcharT>
     path& operator+=(EcharT x);
   template<class Source>
     path& concat(const Source& x);
   

   -1- Effects: […]

   -2- Returns: *this.

   path& operator+=(value_type x);
   template<class EcharT>
     path& operator+=(EcharT x);
   

   -?- Effects: Equivalent to: return *this += basic_string_view(&x, 1);

[ 2019-02; Kona Wednesday night issue processing ]

Status to Ready

[ 2018-10-12 Tim updates PR to avoid suggesting the creation of a temporary path. ]

Previous resolution [SUPERSEDED]:

This wording is relative to N4713.

1. Modify [fs.path.concat] as indicated:

   path& operator+=(const path& x);
   path& operator+=(const string_type& x);
   path& operator+=(basic_string_view<value_type> x);
   path& operator+=(const value_type* x);
   path& operator+=(value_type x);
   template<class Source>
     path& operator+=(const Source& x);
   template<class EcharT>
     path& operator+=(EcharT x);
   template<class Source>
     path& concat(const Source& x);
   

   -1- Effects: […]

   -2- Returns: *this.

   path& operator+=(value_type x);
   template<class EcharT>
     path& operator+=(EcharT x);
   

   -?- Effects: Equivalent to: return *this += path(&x, &x + 1);.

[ 2018-06-18 after reflector discussion ]

Priority set to 3

[fs.path.concat] uses the expression path(x).native() to specify the effects of concatenating a single character x. However, there is no path constructor taking a single character.