before this change, "{:d}" is used for formatting `test_data` y
bptree_stress_test.cc. but the "d" specifier is only used for
formatting integers, not for formatting `test_data` or generic
data types, so this fails when the test is compiled with {fmt} v10,
like:
```
In file included from /home/kefu/dev/scylladb/test/unit/bptree_stress_test.cc:20:
/home/kefu/dev/scylladb/test/unit/bptree_validation.hh:294:35: error: call to consteval function 'fmt::basic_format_string<char, test_data &, test_data &>::basic_format_string<char[31], 0>' is not a constant expression
294 | fmt::print(std::cout, "Iterator broken, {:d} != {:d}\n", val, *_fwd);
| ^
/home/kefu/dev/scylladb/test/unit/bptree_validation.hh:267:20: note: in instantiation of member function 'bplus::iterator_checker<tree_test_key_base, test_data, test_key_compare, 16>::forward_check' requested here
267 | return forward_check();
| ^
/home/kefu/dev/scylladb/test/unit/bptree_stress_test.cc:92:35: note: in instantiation of member function 'bplus::iterator_checker<tree_test_key_base, test_data, test_key_compare, 16>::step' requested here
92 | if (!itc->step()) {
| ^
/usr/include/fmt/core.h:2322:31: note: non-constexpr function 'throw_format_error' cannot be used in a constant expression
2322 | if (!in(arg_type, set)) throw_format_error("invalid format specifier");
| ^
```
in this change, instead of specifying "{:d}", let's just use "{}",
which works for both integer and `test_data`.
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
Closesscylladb/scylladb#16727
0c2ef5de54