EKAT valid_nested_list_format uses size_t for an integer, num_open, that might go negative

[ambrad]

Associated warning:

ekat/src/ekat/util/ekat_string_utils.cpp(179): warning: pointless comparison of unsigned integer with zero

[bartgol]

Thanks! I forgot to add -Wextra to my ekat debug build, and this slipped through the cracks. Will fix.

Side node: imho, such pointless comparisons are potentially dangerous (flawed logic), and gcc should include the warning in -Wall, rather than -Wextra.