Re: c++/10111: Parse error for default template parameter

Re: c++/10111: Parse error for default template parameter

[Martin Sebor]

The following reply was made to PR c++/10111; it has been noted by GNATS.

From: Martin Sebor <sebor@roguewave.com>
To: gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: c++/10111: Parse error for default template parameter
Date: Sun, 16 Mar 2003 17:03:49 -0700

 Giovanni Bajo wrote:
 > http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&p
 > r=10111
 > 
 > Not a real bug. All boils down to a definition like this:
 > 
 > void Foo(int a = A<int,int>::something) {}
 > 
 > There is an open defect report about this
 > (http://www.comeaucomputing.com/iso/cwg_active.html#325), because (shortly)
 > ISO C++ does not mandate that the compiler must understand that the comma is
 > separating template parameters, and not parameters of the function you are
 > declaring.
 
 Not necessarily. The issue is in Open state, so it's still a bug
 at least until the next revision of C++ (assuming issue 325 is
 accepted as a defect) :)
 
 > Simple workaround is putting a couple of paranthesis around the
 > default argument, the code will compile correctly:
 > 
 > void Foo(int a = (A<int,int>::something)) {}
 
 But this still doesn't seem to (at least not with 3.2.2).
 Incidentally, this test case is isolated from std::bitset.
 
 template <class T, class U, class V>
 struct A
 {
      typedef int I;
      static const I i = 0;
 };
 
 template <int I>
 struct B
 {
      template <class T, class U, class V>
      B (const A<T, U, V>&,
         typename A<T, U, V>::I = (typename A<T, U, V>::I ()),
         typename A<T, U, V>::I = (A<T, U, V>::i)) { }
 };
 
 int main ()
 {
      A<int, int, int> a;
 
      B<0> b (a);
 }
 
 Regards
 Martin
 

Re: c++/10111: Parse error for default template parameter

[bangerth]

Synopsis: Parse error for default template parameter

State-Changed-From-To: open->closed
State-Changed-By: bangerth
State-Changed-When: Tue Mar 18 00:08:31 2003
State-Changed-Why:
    Duplicate of PR 57. The code with parenthesis around the
    default arg now compiles in mainline.
    
    Previous versions of gcc gave a really unhelpful message
    on it, funnily:
    
    g/x> /home/bangerth/bin/gcc-3.3-pre/bin/c++ -c x.cc
    x.cc:13: error: parse error before `;' token
    
    Here is this part of the code:
    -----------------
    template <int I>
    struct B
    {
        template <class T, class U, class V>
        B (const A<T, U, V>&,
           typename A<T, U, V>::I = (typename A<T, U, V>::I ()), // #13
           typename A<T, U, V>::I = (A<T, U, V>::i)) { }
    };
    -----------------
    There's not ; on line 13, or anywhere close to it...
    
    W.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10111

Re: c++/10111: Parse error for default template parameter

[Giovanni Bajo]

The following reply was made to PR c++/10111; it has been noted by GNATS.

From: "Giovanni Bajo" <giovannibajo@libero.it>
To: <gcc-gnats@gcc.gnu.org>,
	<gcc-bugs@gcc.gnu.org>,
	<philippeb@videotron.ca>,
	<nobody@gcc.gnu.org>,
	<gcc-prs@gcc.gnu.org>
Cc:  
Subject: Re: c++/10111: Parse error for default template parameter
Date: Sun, 16 Mar 2003 21:04:09 +0100

 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&p
 r=10111
 
 Not a real bug. All boils down to a definition like this:
 
 void Foo(int a = A<int,int>::something) {}
 
 There is an open defect report about this
 (http://www.comeaucomputing.com/iso/cwg_active.html#325), because (shortly)
 ISO C++ does not mandate that the compiler must understand that the comma is
 separating template parameters, and not parameters of the function you are
 declaring. Simple workaround is putting a couple of paranthesis around the
 default argument, the code will compile correctly:
 
 void Foo(int a = (A<int,int>::something)) {}
 
 Notice that both Comeau and VC7.1 accepts this syntax right now, maybe it
 could be worth considering adding it as an "extension" to the mainline. I
 think it's common sense that the code should work.
 
 (Another little note is that the code, as submitted, is ill-formed, typename
 may not be used outside template definitions).
 
 Giovanni Bajo
 

c++/10111: Parse error for default template parameter

[philippeb]

>Number:         10111
>Category:       c++
>Synopsis:       Parse error for default template parameter
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Mar 16 16:16:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     gcc
>Release:        3.0.4
>Organization:
>Environment:
Debian GNU / Linux
>Description:
The default parameter of template type is generating a parse error.
>How-To-Repeat:

>Fix:
Write seperate member function with no default argument of this type.
>Release-Note:
>Audit-Trail:
>Unformatted:
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Content-Transfer-Encoding: base64
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