[Bug c/60018] New: Bogus conversion warning with optimization flag -O1

[Bug c/60018] New: Bogus conversion warning with optimization flag -O1

[chengniansun at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60018

            Bug ID: 60018
           Summary: Bogus conversion warning with optimization flag -O1
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: chengniansun at gmail dot com

The -Wconversion should not be affected by the optimization flags. 

For the following code, Gcc emits no warning with flag -O0, but one conversion
warning with flag -O1. 



$: cat s.c
extern void fn1(unsigned);
extern void fn3(void);
void fn2(void);
void fn2() {
  fn1((fn3(), 0) || 0);
}
$: gcc-trunk -c -Wconversion -std=c11 -O0 s.c
$: gcc-trunk -c -Wconversion -std=c11 -O1 s.c
s.c: In function ‘fn2’:
s.c:5:7: warning: conversion to ‘unsigned int’ from ‘int’ may change the sign
of the result [-Wsign-conversion]
   fn1((fn3(), 0) || 0);
       ^
$: gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/home/chengniansun/tools/gcc-trunk-binaries/libexec/gcc/x86_64-unknown-linux-gnu/4.9.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --enable-languages=c,c++
--disable-multilib --prefix=/home/chengniansun/tools/gcc-trunk-binaries :
(reconfigured) ../gcc-trunk/configure --enable-languages=c,c++
--disable-multilib --prefix=/home/chengniansun/tools/gcc-trunk-binaries :
(reconfigured) ../gcc-trunk/configure --enable-languages=c,c++
--disable-multilib --prefix=/home/chengniansun/tools/gcc-trunk-binaries
Thread model: posix
gcc version 4.9.0 20140131 (experimental) (GCC)
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From: "ppluzhnikov at google dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/60019] New: [C++11] Bogus error: use of deleted function unique_ptr(const unique_ptr&)
Date: Sat, 01 Feb 2014 06:20:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60019

            Bug ID: 60019
           Summary: [C++11] Bogus error: use of deleted function
                    unique_ptr(const unique_ptr&)
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ppluzhnikov at google dot com

Google ref: b/12846752

Test:

#include <memory>
struct S {};
struct T : S {};

std::unique_ptr<T> F();
const std::unique_ptr<S> s = F();


Using recent trunk:
g++ (GCC) 4.9.0 20140129 (experimental)

t.cc:6:32: error: use of deleted function ‘std::unique_ptr<_Tp,
_Dp>::unique_ptr(const std::unique_ptr<_Tp, _Dp>&) [with _Tp = S; _Dp =
std::default_delete<S>]’
 const std::unique_ptr<S> s = F();
                                ^


There is a copy constructor in unique_ptr.h that
I believe is supposed to apply here:

      /** @brief Converting constructor from another type
       *
       * Requires that the pointer owned by @p __u is convertible to the
       * type of pointer owned by this object, @p __u does not own an array,
       * and @p __u has a compatible deleter type.
       */
      template<typename _Up, typename _Ep, typename = _Require<
               is_convertible<typename unique_ptr<_Up, _Ep>::pointer, pointer>,
               __not_<is_array<_Up>>,
               typename conditional<is_reference<_Dp>::value,
                                    is_same<_Ep, _Dp>,
                                    is_convertible<_Ep, _Dp>>::type>>
        unique_ptr(unique_ptr<_Up, _Ep>&& __u) noexcept
        : _M_t(__u.release(), std::forward<_Ep>(__u.get_deleter()))
        { }

but for some reason it doesn't kick in.

(Code builds fine under Clang.)
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From: "lanxingcan at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/60020] New: Considering backport regexp support to 4.8+
Date: Sat, 01 Feb 2014 07:13:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id`020

            Bug ID: 60020
           Summary: Considering backport regexp support to 4.8+
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: lanxingcan at gmail dot com

As GCC 4.8.1+ is already C++11 languages feature complete, it's pity that
regex, a major part of C++11 library feature does not supported in 4.8.x
serials. Any plan on backport regexp support to GCC 4.8.x?

[Bug c/60018] Bogus conversion warning with optimization flag -O1

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60018

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-02-03
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed, not a regression.

[Bug c/60018] Bogus conversion warning with optimization flag -O1

[mpolacek at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60018

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
The issue is that at -O0 conversion_warning gets (fn3(), 0) || 0 and doesn't
call unsafe_conversion_p on it, while on -O fold_binary folds away the || 0
part and conversion_warning sees COMPOUND_EXPR, it then calls
unsafe_conversion_p on it.

I guess nothing for 4.9 now we're in stage4.

[Bug c/60018] Bogus conversion warning with optimization flag -O1

[manu at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60018

Manuel López-Ibáñez <manu at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |manu at gcc dot gnu.org

--- Comment #3 from Manuel López-Ibáñez <manu at gcc dot gnu.org> ---
(In reply to Marek Polacek from comment #2)
> The issue is that at -O0 conversion_warning gets (fn3(), 0) || 0 and doesn't
> call unsafe_conversion_p on it, while on -O fold_binary folds away the || 0
> part and conversion_warning sees COMPOUND_EXPR, it then calls
> unsafe_conversion_p on it.

But in any case, it should look to the last operand of (... , ...) and see that
it is a constant 0. I think there is a duplicate already about -Wconversion not
recursing into compound expressions.
>From gcc-bugs-return-447698-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Mar 28 10:26:17 2014
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Subject: [Bug ipa/60315] [4.8/4.9 Regression] template constructor switch optimization
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id`315

--- Comment #18 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Fri Mar 28 10:25:34 2014
New Revision: 208893

URL: http://gcc.gnu.org/viewcvs?rev 8893&root=gcc&view=rev
Log:
    PR ipa/60315
    * g++.dg/torture/pr60315.C: Add -std=c++11 to dg-options.

Modified:
    trunk/gcc/testsuite/ChangeLog
    trunk/gcc/testsuite/g++.dg/torture/pr60315.C