Re: c++/8057: Templates/non-templates and warnings about statements without effects

Re: c++/8057: Templates/non-templates and warnings about statements without effects

[lerdsuwa]

Synopsis: Templates/non-templates and warnings about statements without effects

State-Changed-From-To: open->analyzed
State-Changed-By: lerdsuwa
State-Changed-When: Sat Sep 28 06:45:47 2002
State-Changed-Why:
    Confirmed.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=8057

c++/8057: Templates/non-templates and warnings about statements without effects

[bangerth]

>Number:         8057
>Category:       c++
>Synopsis:       Templates/non-templates and warnings about statements without effects
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Thu Sep 26 11:56:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Wolfgang Bangerth
>Release:        unknown-1.0
>Organization:
>Environment:
gcc 3.2
>Description:
In the following snippet
------------------------------
struct Y { static int i; };

template <typename T> class X {
    X () { Y::i; };
};
template class X<int>;

class Z {
    Z () { Y::i; };
};
--------------------------------
both the constructors of X and Z access Y::i, in a statement
without effect. This is the error message displayed with
gcc3.2:
--------------------------------
> >  /home/bangerth/bin/gcc-3.2/bin/g++ -o /dev/null -W -Wall -c y.cc
y.cc: In constructor `X<T>::X() [with T = int]':
y.cc:4:   instantiated from `X<T>::X() [with T = int]'
y.cc:6:   instantiated from here
y.cc:4: warning: statement with no effect
y.cc: In constructor `X<T>::X() [with T = int]':
y.cc:4: warning: statement with no effect
----------------------------------------------

In other words: the compiler warns twice about that 
statement in the template class but not at all in the
non-template. This is, well, confusing.

Regards
  Wolfgang
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: