https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61399
--- Comment #6 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- The current proposed wording for DR#467 <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2148.htm#dr_467> changes "maximum representable finite floating-point number, [ math formula ]" to "maximum representable finite floating-point number; if that value is normalized, its value is [ math formula ],", which I think addresses the first issue without requiring any change to LDBL_MAX_EXP; LDBL_MAX should be the largest value, which in this case is not normalized, and LDBL_MAX_EXP has nothing to do with what exponents do or not not have normalized values. (The last proposed change would require LDBL_EPSILON to change, however.) It's true that GCC cannot handle IBM long double constants with more than 106 mantissa bits, including the largest representable finite value.