[Boost-users] BOOST_PP_ERROR(0x0003, BOOST_PP_REPEAT_OVERFLOW) with multiply nested BOOST_PP_REPEATS

Subject: [Boost-users] BOOST_PP_ERROR(0x0003, BOOST_PP_REPEAT_OVERFLOW) with multiply nested BOOST_PP_REPEATS
From: Colin Fowler (fowler_at_[hidden])
Date: 2014-09-26 10:44:35

I'm having a problem with multiple nested repeats. I need to generate 
int x_0_0_0_0 to int x_a_b_c_d. Attempting to do so results in a 
BOOST_PP_ERROR.
For readability, a few shorter defines

#define TUPLE_ELEM BOOST_PP_TUPLE_ELEM
#define REPEAT BOOST_PP_REPEAT

and I also neglect the necessary BOOST_PP_CAT statements in DECL4D in 
this example

#define DECL4D(z, n, text) TUPLE_ELEM(3, text) TUPLE_ELEM(0, text) 
TUPLE_ELEM(1, text) TUPLE_ELEM(2, text) n;
#define DECL4C(z, n, text) REPEAT(TUPLE_ELEM(0, text), DECL4D, 
(TUPLE_ELEM(1, text), TUPLE_ELEM(2, text), n, TUPLE_ELEM(3, text)))
#define DECL4B(z, n, text) REPEAT(TUPLE_ELEM(0, text), DECL4C, 
(TUPLE_ELEM(1, text), TUPLE_ELEM(2, text), n, TUPLE_ELEM(3, text)))
#define DECL4A(z, n, text) REPEAT(TUPLE_ELEM(0, text), DECL4B, 
(TUPLE_ELEM(1, text), TUPLE_ELEM(2, text), n, TUPLE_ELEM(3, text)))
#define decl4(a, b, c, d, text) REPEAT(a, DECL4A, (b, c, d, text))

decl4(1, 1, 1, 1, int x_)

Am I hitting a nesting depth limit or something else? Is there a way 
around this? Ideally I want to write a decl5 macro and have successfully 
written a decl1, decl2 and decl3 so far

Regards,
         Colin