On a domain error, lround() and llround() correctly raise an exception, but do not set errno. They should set errno to EDOM. Background: On error, many glibc math functions both set errno and raise an exception (fetestexcept(3)). For example, the following function all do this: acos(), asin(), cosh(), sinh(), acosh(), asinh(), exp(), exp2(), ldexp(), log(), log10(), log2(). However, there is much inconsistency. Some functions raise an exception, but don't set errno. Some functions set errno for some errors, but not others. A few set errno, but don't raise an exception. This series of bug reports documents deviations from what I consider the ideal: all functions should BOTH set errno AND raise an exception for all errors. All of these reports relate to tests on glibc 2.8 (as provided by SUSE 11.0).
Created attachment 2859 [details] test program
Created attachment 2860 [details] test program Sample runs demonstrating the problem: $ /tmp/mt_lround inf errno == 0 fetestexcept() says: FE_INVALID lround(inf)=-2147483648 0 FE_INVALID normal $ /tmp/mt_llround inf errno == 0 fetestexcept() says: FE_INVALID llround(inf)=-9223372036854775808 0 FE_INVALID normal $ /tmp/mt_lround nan errno == 0 fetestexcept() says: FE_INVALID lround(nan)=-2147483648 0 FE_INVALID normal $ /tmp/mt_llround nan errno == 0 fetestexcept() says: FE_INVALID llround(nan)=-9223372036854775808 0 FE_INVALID normal
See also http://sourceware.org/bugzilla/show_bug.cgi?id=6798
Confirmed with current sources on x86 and x86_64.