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https://issues.apache.org/jira/browse/STDCXX-880?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12591147#action_12591147
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Martin Sebor commented on STDCXX-880:
-------------------------------------
I'm not sure about converting {{double}} to {{max_double_t}}. Is it safe in
terms of traps and floating point exceptions? Is it efficient? Why can't we
just have three overloads of these functions for each of the three floating
point types?
In any event, it's far too late to be changing the implementation of the
{{double}} overloads to {{long double}}, or to be adding non-trivial
implementations the generic functions for 4.2.1. Besides, the new generic
functions are unsafe. They must avoid traps, so any kind of floating point
arithmetic is out of the question. On platforms with limited support for these
kinds of things (e.g., HP-UX on PA-RISC where the arguments must be {{float}}
or {{double}} -- see for example the
[{{fpclassify(3m)}}|http://docs.hp.com/en/B2355-60130/fpclassify.3M.html] HP-UX
man page) we'll have to implement our own versions by examining the bit
patterns ourselves.
For 4.2.1, we need the simplest, safest possible fix, or we need to revert the
patch.
> num_put::put(..., 1.0e+4932L, ...) formats "inf"
> ------------------------------------------------
>
> Key: STDCXX-880
> URL: https://issues.apache.org/jira/browse/STDCXX-880
> Project: C++ Standard Library
> Issue Type: Bug
> Components: 22. Localization
> Affects Versions: trunk
> Reporter: Martin Sebor
> Assignee: Farid Zaripov
> Priority: Blocker
> Fix For: 4.2.1
>
> Attachments: num_put.cpp.diff
>
> Original Estimate: 2h
> Time Spent: 1h
> Remaining Estimate: 1h
>
> The
> [{{22.locale.num.put.cpp}}|http://svn.apache.org/repos/asf/stdcxx/trunk/tests/localization/22.locale.num.put.cpp]
> fails 4 assertions with the head of trunk (see below). The test passes at
> 100% with 4.2.0. I reduced the failures to the following test case:
> {noformat}
> $ cat t.cpp && gmake t && ./t
> #include <cassert>
> #include <cstdio>
> #include <math.h>
> #include <sstream>
> int main ()
> {
> const long double x = 1.0e+4932L;
> assert (isnormal (x));
> std::ostringstream strm;
> strm << x;
> char buf [40];
> std::sprintf (buf, "%Lg", x);
> if (strm.str () == buf)
> return 0;
> std::printf ("%s != %s\n", strm.str ().c_str (), buf);
> assert (0);
> }
> aCC -c -D_RWSTDDEBUG -mt -I/amd/devco/sebor/stdcxx-4.2.x/include
> -I/build/seb
> or/stdcxx-4.2.x-aCC-6.16-15D//include
> -I/amd/devco/sebor/stdcxx-4.2.x/tests/incl
> ude -AA -g +d +DD64 +w +W392,655,684,818,819,849
> +W2193,2236,2261,2340,2401,2
> 487 +W4227,4229,4231,4235,4237,4249 +W4255,4272,4284,4285,4286,4296,4297
> +W3348
> t.cpp
> "/amd/devco/sebor/stdcxx-4.2.x/include/loc/_ctype.h", line 545: warning
> #2186-D:
>
> pointless comparison of unsigned integer with zero
> if ( 0 <= __c
> ^
> "/amd/devco/sebor/stdcxx-4.2.x/include/loc/_ctype.h", line 555: warning
> #2186-D:
>
> pointless comparison of unsigned integer with zero
> if ( 0 <= __c
> ^
> aCC t.o -o t -L/build/sebor/stdcxx-4.2.x-aCC-6.16-15D//rwtest -lrwtest15D -AA
> +n
> ostl -Wl,+s -mt +DD64 -L/build/sebor/stdcxx-4.2.x-aCC-6.16-15D//lib
> -Wl,+b/bu
> ild/sebor/stdcxx-4.2.x-aCC-6.16-15D//lib:/build/sebor/stdcxx-4.2.x-aCC-6.16-15D/
> /rwtest -lstd15D -lm
> inf != 1e+4932
> Assertion failed: 0, file t.cpp, line 22
> ABORT instruction (core dumped)
> {noformat}
> The output of {{22.locale.num.put}} follows:
> {noformat}
> $ ./22.locale.num.put -q
> # ASSERTION (S7) (4 lines):
> # TEXT: line 377: num_put<char>::put (..., long double = 1.18973e+4932) wrote
> "inf", expected "1.18973149535723176508575932662800702e+4932", flags =
> fmtflags(0), precision = 36
> # CLAUSE: lib.locale.num.put
> # LINE: 1854
> # ASSERTION (S7) (4 lines):
> # TEXT: line 377: num_put<char>::put (..., long double = 1e+4932) wrote
> "inf", expected { "1", '0' <repeats 34 times>, "1", '0' <repeats 4897 times>
> }, flags = fixed, precision = 0
> # CLAUSE: lib.locale.num.put
> # LINE: 1958
> # ASSERTION (S7) (4 lines):
> # TEXT: line 377: num_put<wchar_t>::put (..., long double = 1.18973e+4932)
> wrote L"inf", expected "1.18973149535723176508575932662800702e+4932", flags =
> fmtflags(0), precision = 36
> # CLAUSE: lib.locale.num.put
> # LINE: 1854
> # ASSERTION (S7) (4 lines):
> # TEXT: line 377: num_put<wchar_t>::put (..., long double = 1e+4932) wrote
> L"inf", expected { "1", '0' <repeats 34 times>, "1", '0' <repeats 4897 times>
> }, flags = fixed, precision = 0
> # CLAUSE: lib.locale.num.put
> # LINE: 1958
> # +-----------------------+----------+----------+----------+
> # | DIAGNOSTIC | ACTIVE | TOTAL | INACTIVE |
> # +-----------------------+----------+----------+----------+
> # | (S1) INFO | 96 | 96 | 0% |
> # | (S2) NOTE | 1 | 1 | 0% |
> # | (S5) WARNING | 2 | 2 | 0% |
> # | (S7) ASSERTION | 4 | 1671 | 99% |
> # +-----------------------+----------+----------+----------+
> {noformat}
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