[Bug c++/37276] New: Trouble with some (C99?) math builtins and namespace std

[Bug c++/37276] New: Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

Hi, I'm getting this annoying run-time Seg-fault for the below. Apparently,
isn't a regression, but really, if we could fix it, the C++ library would
benefit a lot from the fix!

////////////////

namespace my_std
{
  inline double
  atan(double __x)
  { return __builtin_atan(__x); }

  inline double
  atanh(double __x)
  { return __builtin_atanh(__x); }
}

namespace std
{
  inline double
  atan(double __x)
  { return __builtin_atan(__x); }

  inline double
  atanh(double __x)
  { return __builtin_atanh(__x); }
}

int main()
{
  double d;

  my_std::atan(.3);  // works
  my_std::atanh(.3); // works

  std::atan(.3);     // works
  std::atanh(.3);    // seg-faults at run-time
}


-- 
           Summary: Trouble with some (C99?) math builtins and namespace std
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: paolo dot carlini at oracle dot com


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #1 from paolo dot carlini at oracle dot com  2008-08-29 13:04 -------
I think it can be safely confirmed.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

-- 

paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2008-08-29 13:04:17
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2008-08-29 13:08 -------
Funny.  (just look at the asm...)


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |rguenth at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2008-08-29 13:04:17         |2008-08-29 13:08:02
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-08-29 13:11 -------
Actually, it looks like we treat

namespace std
{
  inline double
  atanh(double __x)
  { return __builtin_atanh(__x); }
}

as a definition of ::atanh (with C linkage), and emit

atanh:
.LFB0:
        pushq   %rbp
.LCFI0:
        movq    %rsp, %rbp
.LCFI1:
        subq    $32, %rsp
.LCFI2:
        movsd   %xmm0, -8(%rbp)
        movsd   -8(%rbp), %xmm0
        call    atanh
        movsd   %xmm0, -24(%rbp)
        movq    -24(%rbp), %rax
        movq    %rax, -24(%rbp)
        movsd   -24(%rbp), %xmm0
        leave
        ret

main:
.LFB1:
        pushq   %rbp
.LCFI3:
        movq    %rsp, %rbp
.LCFI4:
        movsd   .LC0(%rip), %xmm0
        call    atanh
        movl    $0, %eax
        leave
        ret


So, this is a frontend bug.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu dot org
         AssignedTo|rguenth at gcc dot gnu dot  |unassigned at gcc dot gnu
                   |org                         |dot org
             Status|ASSIGNED                    |NEW
           Keywords|                            |wrong-code


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #4 from paolo dot carlini at oracle dot com  2008-08-29 14:18 -------
>From the "outside", without looking deeper, I agree it seems a front-end issue.
The following seg-faults only when built with the C++ compiler:

inline double
atanh(double __x)
{ return __builtin_atanh(__x); }

int main()
{
  atanh(.3);
  return 0;
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2008-08-29 15:52 -------
I think this testcase is invalid without -std=c++98.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #6 from paolo dot carlini at oracle dot com  2008-08-29 15:56 -------
Why?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #7 from paolo dot carlini at oracle dot com  2008-08-29 16:01 -------
The strict c++98 standard, without GNU extensions, doesn't know anything about
atanh - there isn't a single mention in the entire Standard - therefore I don't
see why any difference is wanted. Even less I see why we want Seg-faults at
run-time. Even less, why we want that in the C++0x era, when C99 math
facilities are on a par with C89 ones.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #8 from paolo dot carlini at oracle dot com  2008-08-29 16:05 -------
(In reply to comment #7)
> The strict c++98 standard, without GNU extensions, doesn't know anything about
> atanh - there isn't a single mention in the entire Standard - therefore I don't
> see why any difference is wanted.

Sorry, I got this first part of my reply backward. In any case, I don't think
enabling the GNU extensions (-std=gnu++98 is the default) should lead to such
nasty problem.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #9 from paolo dot carlini at oracle dot com  2008-08-29 18:46 -------
FWIW, this kind of contortion appear to work, but really I'd rather prefer not
using it...

namespace my_std
{
  inline double
  atan(double __x)
  { return __builtin_atan(__x); }

  inline double
  atanh(double __x)
  { return __builtin_atanh(__x); }
}

namespace std
{
  using ::my_std::atan;
  using ::my_std::atanh;
}

int main()
{
  std::atan(.3);     // works
  std::atanh(.3);    // works
}


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[rguenther at suse dot de]

------- Comment #10 from rguenther at suse dot de  2008-08-30 14:25 -------
Subject: Re:  Trouble with some (C99?) math builtins and
 namespace std

On Fri, 29 Aug 2008, paolo dot carlini at oracle dot com wrote:

> ------- Comment #9 from paolo dot carlini at oracle dot com  2008-08-29 18:46 -------
> FWIW, this kind of contortion appear to work, but really I'd rather prefer not
> using it...

So from the previous replies I gather that if one adds a symbol
to the std:: namespace the new additions are not mangled if their
unmangled name is used by a GNU extension?  For what reason?
At least I would miss a warning here that atanh is re-declared in
a different namespace or so.

Richard.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[paolo dot carlini at oracle dot com]

------- Comment #11 from paolo dot carlini at oracle dot com  2009-07-14 14:00 -------
Jason, this is the issue, you are in CC. Actually, using declarations are not
directly involved - I was misremembering - are only part of my ugly workaround,
and, beware, I menace to use it... ;)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[jason at gcc dot gnu dot org]

------- Comment #12 from jason at gcc dot gnu dot org  2009-07-14 18:16 -------
Subject: Bug 37276

Author: jason
Date: Tue Jul 14 18:16:03 2009
New Revision: 149638

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=149638
Log:
        PR c++/37276
        * decl.c (decls_match): A non-extern-C declaration doesn't match
        a builtin extern-C declaration.

Added:
    trunk/gcc/testsuite/g++.dg/lookup/builtin5.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/other/error22.C
    trunk/gcc/testsuite/g++.dg/warn/Warray-bounds.C
    trunk/gcc/testsuite/gcc.dg/compat/compat-common.h


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[jason at gcc dot gnu dot org]

------- Comment #13 from jason at gcc dot gnu dot org  2009-07-14 18:44 -------
Fixed for 4.5.


-- 

jason at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

[Bug c++/37276] Trouble with some (C99?) math builtins and namespace std

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37276

--- Comment #14 from Jason Merrill <jason at gcc dot gnu.org> 2012-11-15 01:53:55 UTC ---
Author: jason
Date: Thu Nov 15 01:53:48 2012
New Revision: 193526

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=193526
Log:
    PR c++/37276
    * decl.c (decls_match): Remove #ifdef around earlier fix.

Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c