[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[ilya.konstantinov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

Ilya Konstantinov <ilya.konstantinov at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ilya.konstantinov at gmail dot com

--- Comment #6 from Ilya Konstantinov <ilya.konstantinov at gmail dot com> ---
This bug causes an error using llvm's libc++, e.g.:

#include <string>
void foo() {
  string::iterator it; // friend-declares vector<_Tp,_Alloc>
}

#include <vector>
using std::vector; // <-- error: 'vector' is already declared in this scope

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[ilya.konstantinov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

--- Comment #7 from Ilya Konstantinov <ilya.konstantinov at gmail dot com> ---
Whoever has permission to change, please add 'rejects-valid' as per my example
in the previous comment.

P.S. this issue reproduces in g++ 4.8

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Here's the reduced form of the rejects-valid case from comment 6

namespace std
{
  template <typename T>
    struct basic_string
    {
      template<typename U>
        friend struct vector;
    };
}

std::basic_string<char> it;   // injects std::vector<T> into global scope

namespace std
{
  template<typename U>
    struct vector { };
}

using std::vector;


f.cc:19:12: error: ‘vector’ is already declared in this scope
 using std::vector;
            ^

That seems slightly different, as it only misbehaves when std::vector is a
template, i.e. this version compiles OK:

namespace std
{
  template <typename T>
    struct basic_string
    {
        friend struct foo;
    };
}

std::basic_string<char> it;   // does not inject std::foo

namespace std
{
    struct foo { };
}

using std::foo;


Curiously, although the error for the first example says vector has already
been declared at global scope, it apparently refers to std::vector and yet is
considered incomplete:

namespace std
{
  template <typename T>
    struct basic_string
    {
      template<typename U>
        friend struct bar;
    };
}

std::basic_string<char> it;   // injects std::bar<T> into global scope

namespace std
{
  template<typename U>
    struct bar { };
}

bar<int> b;

fr.cc:19:10: error: aggregate ‘std::bar<int> b’ has incomplete type and cannot
be defined
 bar<int> b;
          ^
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From: "dominiq at lps dot ens.fr" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/61387] New: [4.10 Regression] ~900 test failures on on x86_64-apple-darwin13 for g++ with -m64 after r211088
Date: Mon, 02 Jun 2014 09:48:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ida387

            Bug ID: 61387
           Summary: [4.10 Regression] ~900 test failures on on
                    x86_64-apple-darwin13 for g++ with -m64 after r211088
           Product: gcc
           Version: 4.10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dominiq at lps dot ens.fr
                CC: iains at gcc dot gnu.org, ktietz70 at googlemail dot com
              Host: x86_64-apple-darwin13
            Target: x86_64-apple-darwin13
             Build: x86_64-apple-darwin13

After r211088 I see ~900 test failures on on x86_64-apple-darwin13 for g++ with
-m64.
The tests fail with two kinds of ICEs:

/opt/gcc/_clean/gcc/testsuite/g++.dg/torture/pr58585.C: In member function
'virtual void B::_ZTv0_n24_N1B3fooEv()':
/opt/gcc/_clean/gcc/testsuite/g++.dg/torture/pr58585.C:20:17: error:
unrecognizable insn:
 C::C() { bar(); }
                 ^
(call_insn/j 4 3 5 (call (mem/u/c:DI (const:DI (unspec:DI [
                        (symbol_ref/i:DI ("_ZN1B3fooEv") [flags 0x1]
<function_decl 0x142785f00 foo>)
                    ] UNSPEC_GOTPCREL)) [0  S8 A8])
        (const_int 0 [0]))
/opt/gcc/_clean/gcc/testsuite/g++.dg/torture/pr58585.C:12 -1
     (nil)
    (nil))
/opt/gcc/_clean/gcc/testsuite/g++.dg/torture/pr58585.C:20:17: internal compiler
error: in insn_default_length, at config/i386/i386.md:1786

or

/opt/gcc/_clean/gcc/testsuite/g++.dg/debug/pr54499.C: In member function
'virtual void S3::_ZThn8_N2S3D1Ev()':
/opt/gcc/_clean/gcc/testsuite/g++.dg/debug/pr54499.C:22:1: error:
unrecognizable insn:
 }
 ^
(call_insn/j 3 2 4 (call (mem/u/c:DI (const:DI (unspec:DI [
                        (symbol_ref/i:DI ("_ZN2S3D1Ev") [flags 0x1]
<function_decl 0x14278e500 __comp_dtor >)
                    ] UNSPEC_GOTPCREL)) [0  S8 A8])
        (const_int 0 [0]))
/opt/gcc/_clean/gcc/testsuite/g++.dg/debug/pr54499.C:14 -1
     (nil)
    (nil))
/opt/gcc/_clean/gcc/testsuite/g++.dg/debug/pr54499.C:22:1: internal compiler
error: in insn_default_length, at config/i386/i386.md:1786

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |11.0

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed in GCC 11, most likely by r11-3361, the testcase and the case here look
very similar.

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[jason at gcc dot gnu dot org]

------- Comment #5 from jason at gcc dot gnu dot org  2009-01-15 23:07 -------
7.3.1.2: If a friend declaration in a non-local class first declares a class or
function the friend class or function is a member of the innermost enclosing
namespace. The name of the friend is not found by unqualified lookup (3.4.1) or
by qualified lookup (3.4.3) until a matching declaration is provided in that
namespace scope (either before or after the class definition granting
friendship).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2008-12-30 11:52 -------
14.6.5 [temp.inject]

suggests that this is valid.  EDG doesn't agree with that in strict-ansi mode.

t2.C(9): error: identifier "B" is undefined
  B some_function();  // B should not be declared here
  ^

compilation aborted for t2.C (code 2)

(testcase from comment #1)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-10-11 18:46 -------
Related to PR37775, PR34827 and PR31336.  (search for accepts-invalid and
'friend')

Seems like friend declarations are not an uncommon source for problems...


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at redhat dot com
  BugsThisDependsOn|                            |31336, 34827, 37775


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[pinskia at gmail dot com]

------- Comment #2 from pinskia at gmail dot com  2008-10-11 17:05 -------
Subject: Re:   New: Nested type leaks to global scope



Sent from my iPhone

On Oct 11, 2008, at 5:28 AM, "therealfroggey at gmail dot com"
<gcc-bugzilla@gcc.gnu.org 
 > wrote:

> GCC versions used:
> gcc version 4.1.2
> gcc version 4.4.0 20081011 (experimental) (GCC) svn revision 141055
> Command line used: g++ -Wall -Wextra bug.cc
>
> The following code should fail to compile as Internal_B is a private  
> class
> within class A.
> Both tested version of gcc successfully compile it with no warnings.
>
> ------------
>
> template <typename T>
> class A
> {
> private:
>  class Internal_A
>  {
>    friend class Internal_B;

The above friend class refers to the class in containing namespace and  
not to the class inside the class.

>
>  };
>  class Internal_B { };
>  Internal_A a;
> };
>
> A<int> a;
>
> Internal_B some_function();

The above should not compile but it is not because the inner class is  
leaking though. It is because the friend statement is causing an  
injection when it should not.

>
>
>
> -- 
>           Summary: Nested type leaks to global scope
>           Product: gcc
>           Version: 4.4.0
>            Status: UNCONFIRMED
>          Severity: normal
>          Priority: P3
>         Component: c++
>        AssignedTo: unassigned at gcc dot gnu dot org
>        ReportedBy: therealfroggey at gmail dot com
> GCC build triplet: x86_64-linux-gnu
>  GCC host triplet: x86_64-linux-gnu
> GCC target triplet: x86_64-linux-gnu
>
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804
>


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804

[Bug c++/37804] friend declaration leaks into global scope at template instantiation

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2008-10-11 13:07 -------
Confirmed.  The friend declaration seems to inject Internal_B into the global
namespace at the point of instantiating the template A.

Reduced testcase:

template <typename T>
struct A
{
  friend class B;
};

A<int> a; // here we inject a declaration of B into the global namespace

B some_function();  // B should not be declared here


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |accepts-invalid
   Last reconfirmed|0000-00-00 00:00:00         |2008-10-11 13:07:05
               date|                            |
            Summary|Nested type leaks to global |friend declaration leaks
                   |scope                       |into global scope at
                   |                            |template instantiation


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37804