[Bug c++/57645] New: Explicitly-declared destructor with no exception specification is always noexcept(true)

[Bug c++/57645] New: Explicitly-declared destructor with no exception specification is always noexcept(true)

[travis at gockelhut dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

            Bug ID: 57645
           Summary: Explicitly-declared destructor with no exception
                    specification is always noexcept(true)
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: travis at gockelhut dot com

#include <type_traits>

struct Thrower
{
    ~Thrower() noexcept(false) { throw 1; }
};

struct Explicit
{
    ~Explicit() {}

    Thrower t;
};
static_assert(!std::is_nothrow_destructible<Explicit>::value, "Explicit");


This will fail on the static_assert in 4.8, in contrast to §15.4.14:

> ..If f is an...destructor...it's implicit exception-specification specifies...f has the exception-specification noexcept(true) if every function it directly invokes allows no exceptions.

And Thrower::~Thrower is directly invoked according to §12.4.8:

> After executing the body of the destructor and destroying any automatic objects allocated within the body, a destructor for class X calls the destructors for X’s direct non-variant non-static data members...
>From gcc-bugs-return-424607-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Jun 19 05:21:51 2013
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From: "b.r.longbons at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/57646] New:=?UTF-8?Q? bogus warning about uninitialized ‘saved_stack?=.=?UTF-8?Q?1’ with gotos and VLAs?Date: Wed, 19 Jun 2013 05:21:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57646

            Bug ID: 57646
           Summary: bogus warning about uninitialized ‘saved_stack.1’ with
                    gotos and VLAs
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: b.r.longbons at gmail dot com

Created attachment 30321
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30321&action=edit
minimal testcase

The attached reduced testcase gives a warning that a nonexistent variable,
'saved_stack.1', may be used uninitialized.

The testcase does not need any special compiler flags.

There are a bunch of bugs with similar descriptions, but they either don't
involve invented variables or were marked as fixed.
In particular, it looks fairly similar to bug 43013, which was fixed before
4.6.0. The differences I can see are that this only seems to happen in C++ with
VLAs.

Bad versions, all amd64:
Gentoo: 4.4.7, 4.5.4, 4.6.0, 4.6.1, 4.6.2, 4.6.3, 4.6.4, 4.7.0, 4.7.1, 4.7.2,
4.7.3
Debian: 4.6.4-2, 4.7.3-4, 4.8.1-2

4.3.6 does not exhibit this issue, but that's too old to compile the codebase
this is in. Since I haven't found a workaround short of disabling the warning,
I'm stuck with clang for now, which lacks support for a lot of other essential
warnings (*grumbles about old bug reports that still aren't fixed*).
>From gcc-bugs-return-424608-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Jun 19 06:38:48 2013
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From: "vijunag at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/57647] New: lvalue required as increment operand
Date: Wed, 19 Jun 2013 06:38:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idW647

            Bug ID: 57647
           Summary: lvalue required as increment operand
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: vijunag at gmail dot com

I recently upgraded my gcc compiler from 3.4.X to 4.7.2 for my project.

Consider the following expression

char *foo = &bar;
((unsigned long*)foo)++

While gcc 3.4.X was more forgiving of this issue, 4.7.2 barfs out an error
"lvalue required as increment operand".

I did notice in gcc documentation that "cast as l-value has been removed".

C and Objective-C

    The -Wstrict-aliasing=2 option has been added. This warning catches all
unsafe cases, but it may also give a warning for some cases that are safe.
    The cast-as-lvalue, conditional-expression-as-lvalue and
compound-expression-as-lvalue extensions, which were deprecated in 3.3.4 and
3.4, have been removed.
    The -fwritable-strings option, which was deprecated in 3.4, has been
removed.
    #pragma pack() semantics have been brought closer to those used by other
compilers. This also applies to C++.
    Taking the address of a variable with register storage is invalid in C. GCC
now issues an error instead of a warning.
    Arrays of incomplete element type are invalid in C. GCC now issues an error
for such arrays. Declarations such as extern struct s x[]; (where struct s has
not been defined) can be moved after the definition of struct s. Function
parameters declared as arrays of incomplete type can instead be declared as
pointers.

So the natural fix and equivalent legitimate expression for the same would
((unsigned long *)foo++), however with -Wall gcc again warns about
unused-value.

While gcc accepts the expression ((unsigned long*)foo++), the expression has
become useless when -Wall -Werror  is turned on since it throws
"-Werror=unused-value".

Either the expression should completely be removed or GCC should stop warning
about such expressions.

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-06-19
           Assignee|unassigned at gcc dot gnu.org      |paolo.carlini at oracle dot com
            Summary|Explicitly-declared         |[4.8/4.9 Regression]
                   |destructor with no          |Explicitly-declared
                   |exception specification is  |destructor with no
                   |always noexcept(true)       |exception specification is
                   |                            |always noexcept(true)
     Ever confirmed|0                           |1

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Humpf, this regressed with PR50043. Apparently something is going wrong with
the way we are implementing 12.4/3, because this is still fine:

struct Thrower
{
  ~Thrower() noexcept(false) { throw 1; }
};

struct Explicit
{
  // ~Explicit() {}

  Thrower t;
};

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Created attachment 30357
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30357&action=edit
An extended set of tests

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
   Target Milestone|---                         |4.8.2

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed in mainline so far.

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed for 4.8.2 too.

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[dspeterson at tagged dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

Dave Peterson <dspeterson at tagged dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dspeterson at tagged dot com

--- Comment #5 from Dave Peterson <dspeterson at tagged dot com> ---
class TException {
};

class TThrower {
  public:
  ~TThrower() {
    throw TException();
  }
};

int main(int /*argc*/, char ** /*argv*/) {
  try {
    TThrower thrower;
  } catch (const TException &) {
  }

  return 0;
}



I compile and run the above program with g++ 4.8.2 and get
the following behavior:

    terminate called after throwing an instance of 'TException'
    Aborted (core dumped)

So it looks like the issue still isn't fixed.

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[daniel.kruegler at googlemail dot com]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset="UTF-8", Size: 3873 bytes --]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

--- Comment #6 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Dave Peterson from comment #5)
In C++11 terminate is expected for this code, because the implied exception
specification of any destructor is noexcept(true), so throwing an exception
here is a bad idea. You have to add noexcept(false) or you have to switch to
C++03 mode to make it work.
>From gcc-bugs-return-435952-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Tue Nov 26 23:45:24 2013
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From: "burnus at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug sanitizer/59306] New: ICE with -fsanitize=null: gimple check: expected gimple_call(error_mark), have gimple_assign(addr_expr) in gimple_call_arg
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idY306

            Bug ID: 59306
           Summary: ICE with -fsanitize=null: gimple check: expected
                    gimple_call(error_mark), have gimple_assign(addr_expr)
                    in gimple_call_arg
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: sanitizer
          Assignee: unassigned at gcc dot gnu.org
          Reporter: burnus at gcc dot gnu.org
                CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
                    jakub at gcc dot gnu.org, kcc at gcc dot gnu.org,
                    mpolacek at gcc dot gnu.org

Created attachment 31303
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id1303&actioníit
Simple C++ testcase, compile with -fsanitize=null

Now that a bunch of sanitizer bugs have been fixed on the trunk, I tried
-fsanitize=null again. However, I run into another ICE with that option:

$ g++ -fsanitize=null test14.ii

test14.ii: In member function 'void
VwEventHandler::CreateEventHandlerThread()':
test14.ii:14:1: internal compiler error: gimple check: expected
gimple_call(error_mark), have gimple_assign(addr_expr) in gimple_call_arg, at
gimple.h:2477
 }
 ^
0x9d2d8c gimple_check_failed(gimple_statement_base const*, char const*, int,
char const*, gimple_code, tree_code)
        ../../gcc/gimple.c:1132
0x563c9a gimple_call_arg
        ../../gcc/gimple.h:2477

[Bug c++/57645] [4.8/4.9 Regression] Explicitly-declared destructor with no exception specification is always noexcept(true)

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57645

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|paolo.carlini at oracle dot com    |unassigned at gcc dot gnu.org

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Indeed. Thanks Daniel. I have just confirmed that everything is fine for the
released 4.8.2.