{"abcd", "_b_d", runeZero, true, nil},

		{"abcd", "____", runeZero, true, nil},
		{"abcd", "____%", runeZero, true, nil},
		{"abcd", "%____", runeZero, true, nil},
		{"abcd", "%__", runeZero, true, nil},
		{"abcd", "____", runeZero, true, nil},

		{"", "_", runeZero, false, nil},
		{"", "%", runeZero, true, nil},
		{"abcd", "%%%%%", runeZero, true, nil},
		{"abcd", "_____", runeZero, false, nil},

		mp_limb_t *_mp_d;
	} __mpz_struct;

	typedef __mpz_struct mpz_t[1];

Cgo generates:

	type _C_int int32
	type _C_mp_limb_t uint64
	type _C___mpz_struct struct {
		_mp_alloc _C_int;
		_mp_size _C_int;
		_mp_d *_C_mp_limb_t;
	}
	type _C_mpz_t [1]_C___mpz_struct

and then replaces each occurrence of a type C.xxx with _C_xxx.

If xxx is data, cgo arranges for C.xxx to refer to the C variable,

		return s == "__cgodebug_ints" || s == "___cgodebug_ints"
	}
	isDebugFloats := func(s string) bool {
		// Some systems use leading _ to denote non-assembly symbols.
		return s == "__cgodebug_floats" || s == "___cgodebug_floats"
	}
	indexOfDebugStr := func(s string) int {
		// Some systems use leading _ to denote non-assembly symbols.
		if strings.HasPrefix(s, "___") {
			s = s[1:]
		}