This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21 Core Issues List revision 115e. See http://www.open-std.org/jtc1/sc22/wg21/ for the official list.

2024-11-11

518. Trailing comma following enumerator-list

[Voted into WP at April, 2006 meeting.]

The C language (since C99), and some C++ compilers, accept:

    enum { FOO, };

as syntactically valid. It would be useful

• for machine generated code

• for minimising changes when editing

• to allow a distinction between the final item being intended as an ordinary item or as a limit:

  enum { red, green, blue, num_colours };  // note no comma
  enum { fred, jim, sheila, };             // last is not special

This proposed change is to permit a trailing comma in enum by adding:

enum identifier_opt { enumerator-list , }

as an alternative definition for the enum-specifier nonterminal in 9.7.1 [dcl.enum] paragraph 1.

Proposed resolution (October, 2005):

Change the grammar in 9.7.1 [dcl.enum] paragraph 1 as indicated:

enum-specifier:

enum identifier_opt { enumerator-list_opt }

enum identifier_opt { enumerator-list , }