Date: Tue, 30 Dec 2008 22:31:30 GMT From: Vaclav Haisman <v.haisman@sh.cvut.cz> To: freebsd-gnats-submit@FreeBSD.org Subject: standards/130067: Wrong numeric limits in system headers? Message-ID: <200812302231.mBUMVUtf092910@www.freebsd.org> Resent-Message-ID: <200812302240.mBUMe1rr009426@freefall.freebsd.org>
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>Number: 130067 >Category: standards >Synopsis: Wrong numeric limits in system headers? >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-standards >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Dec 30 22:40:01 UTC 2008 >Closed-Date: >Last-Modified: >Originator: Vaclav Haisman >Release: 6.3 >Organization: SU SH >Environment: FreeBSD shell.sh.cvut.cz 6.3-PRERELEASE FreeBSD 6.3-PRERELEASE #0: Fri Jan 18 17:04:16 CET 2008 root@shell.sh.cvut.cz:/usr/obj/usr/src/sys/SHELL-SMP i386 >Description: There seems to be a problem with definition of long double limits on FreeBSD i386/6.x. shell::wilx:~/packed_vector> echo | g++ -dD -E - | sort | grep LDBL_MAX #define __LDBL_MAX_10_EXP__ 4932 #define __LDBL_MAX_EXP__ 16384 #define __LDBL_MAX__ 1.1897314953572316e+4932L shell::wilx:~/packed_vector> fgrep -rn LDBL_MAX /usr/include [...] /usr/include/machine/float.h:75:#define LDBL_MAX_EXP 16384 /usr/include/machine/float.h:76:#define LDBL_MAX 1.1897314953572317650E+4932L /usr/include/machine/float.h:77:#define LDBL_MAX_10_EXP 4932 /usr/include/float.h:75:#define LDBL_MAX_EXP 16384 /usr/include/float.h:76:#define LDBL_MAX 1.1897314953572317650E+4932L /usr/include/float.h:77:#define LDBL_MAX_10_EXP 4932 Notice the difference in definition of LDBL_MAX, the values in system headers are tiny bit larger than that defined by GCC itself. machine/float.h:76:#define LDBL_MAX 1.1897314953572317650E+4932L float.h:76:#define LDBL_MAX 1.1897314953572317650E+4932L GCC: __LDBL_MAX__ 1.1897314953572316e+4932L A simple test shows the following: shell::wilx:~/tmp> cat >longdouble.cxx #include <iostream> #include <limits> #include <cfloat> int main () { typedef std::numeric_limits<long double> limits; std::cout << "max: " << limits::max () << "\n"; std::cout << "__LDBL_MAX__: " << __LDBL_MAX__ << "\n"; std::cout << "LDBL_MAX: " << LDBL_MAX << "\n"; } shell::wilx:~/tmp> g++ -o longdouble longdouble.cxx shell::wilx:~/tmp> ./longdouble max: 1.18973e+4932 __LDBL_MAX__: 1.18973e+4932 LDBL_MAX: inf This is on 6.3/i386. 7.1/AMD64 does not print inf for LDBL_MAX. I think this is a bug in 6.x headers or in GCC 3.4.x that it uses. LDBL_MAX should never result in "inf". >How-To-Repeat: #include <iostream> #include <limits> #include <cfloat> int main () { typedef std::numeric_limits<long double> limits; std::cout << "max: " << limits::max () << "\n"; std::cout << "__LDBL_MAX__: " << __LDBL_MAX__ << "\n"; std::cout << "LDBL_MAX: " << LDBL_MAX << "\n"; } >Fix: >Release-Note: >Audit-Trail: >Unformatted:
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