BTW, last month I posted a patch for this PR that handles all kinds of
specifiers as well __attribute__ specifiers.
Patch is at: https://gcc.gnu.org/ml/gcc-patches/2016-01/msg02004.html
-- it makes the parser arbitrarily look ahead (while skipping over
pairs of parens) until it finds a DEREF, a COMMA, a CLOSE_PAREN or an
EQ. If it first finds a DEREF then have_trailing_return_fn_decl is
set. Dunno if it's better to have this kind of "dumb" lookahead, or
to be more explicit about one expects to consume like your followup
patch does.