[Bug c++/10118] [3.3/3.4 Regression] Conversion of ptrmem to derived class in template arg fails

[Bug c++/10118] [3.3/3.4 Regression] Conversion of ptrmem to derived class in template arg fails

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
            Summary|Conversion of ptrmem to     |[3.3/3.4 Regression]
                   |derived class in template   |Conversion of ptrmem to
                   |arg fails                   |derived class in template
                   |                            |arg fails
   Target Milestone|---                         |3.3.2


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-17 00:06 -------
2.91.66 accepted this so this is a regression.

[Bug c++/10118] [3.3/3.4 Regression] Conversion of ptrmem to derived class in template arg fails

[mmitchel at gcc dot gnu dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118


mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|rejects-valid               |diagnostic
   Target Milestone|3.3.2                       |---


------- Additional Comments From mmitchel at gcc dot gnu dot org  2003-09-05 18:44 -------
This code is invalid; the cast may not appear as part of a template argument.

Clearly, the error message (with the brace notation) is sub-optimal.

I've removed the target milestone because I don't know if the error message has
regressed; the audit trail says that most versions of G++ have correctly
rejected this code.

[Bug c++/10118] Conversion of ptrmem to derived class in template arg fails

[bangerth at dealii dot org]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118


bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[3.3/3.4 Regression]        |Conversion of ptrmem to
                   |Conversion of ptrmem to     |derived class in template
                   |derived class in template   |arg fails
                   |arg fails                   |


------- Additional Comments From bangerth at dealii dot org  2003-09-05 18:49 -------
Since this is invalid code, it's no longer a regression.

Also, the error message is not a regression. 2.95 gives
g/x> c++ -c x.cc
x.cc:7: `(&A::foo)' is not a valid template argument
x.cc:7: it must be a pointer-to-member of the form `&X::Y'
x.cc:7: ANSI C++ forbids declaration `c' with no type

That's about as bad as what we now get. The message is clearly
suboptimal nevertheless, so let's keep this PR open.

W.

[Bug c++/10118] Bad diagnostic with cast in template argument expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-12-05 02:44 -------
this is semi-fixed on the mainline (get rid of the "()" and it would be considered fixed, unless 
someone says otherwise. )
pr1011.cc:7: error: `A::foo()' cannot appear in a constant-expression
pr1011.cc:7: error: a casts to a type other than an integral or enumeration type cannot appear in a 
constant-expression
pr1011.cc:7: error: template argument 2 is invalid
pr1011.cc:7: error: expected constructor, destructor, or type conversion

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |minor


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118

[Bug c++/10118] Bad diagnostic with cast in template argument expression

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-12-05 03:31 -------
I see two open issues here: first, the error message has wrong 
grammar ("a cast_s_"). 
 
The second thing is that what is being attempted here doesn't seem 
to be possible: neither of these work: 
 
CT<B, &A::foo>  c1; 
CT<B, &B::foo>  c2; 
CT<B, (B_ptr)&B::foo>  c3; 
 
The second one is particularly confusing, since &B::foo immediately decays 
to A::*, but this has recently been discussed in another PR and seems to 
be standards conforming. The last one should cast this back, but this 
isn't allowed. The first one should of course be wrong. So we are left 
with a situation where something just can't be done. Someone should 
file a DR for this, this is clearly a less than satisfactory situation... 
 
W. 

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118

[Bug c++/10118] Bad diagnostic with cast in template argument expression

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-08-20 06:52 -------
Slightly error message change:
pr10118.cc:8: error: `A::foo()' cannot appear in a constant-expression
pr10118.cc:8: error: `&' cannot appear in a constant-expression
pr10118.cc:8: error: a cast to a type other than an integral or enumeration type cannot appear in a 
constant-expression
pr10118.cc:8: error: template argument 2 is invalid
pr10118.cc:8: error: invalid type in declaration before ';' token

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2004-05-21 03:50:25         |2004-08-20 06:52:50
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118

[Bug c++/10118] Bad diagnostic with cast in template argument expression

[gdr at integrable-solutions dot net]

------- Additional Comments From gdr at integrable-solutions dot net  2004-08-20 07:12 -------
Subject: Re:  Bad diagnostic with cast in template argument expression

"pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> writes:

| Slightly error message change:
| pr10118.cc:8: error: `A::foo()' cannot appear in a constant-expression

This is wrong and I know why.  The code cp/error.c is too contrived to
fix it properly.  It is better to rely on the code in
cp/cxx-pretty-print.c to fix it.

| pr10118.cc:8: error: `&' cannot appear in a constant-expression

This does nto make any sense.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10118