[Bug c++/24657] New: bizarre diagnostic on valid (?) constructor

[Bug c++/24657] New: bizarre diagnostic on valid (?) constructor

[igodard at pacbell dot net]

The first error reported in the attached is:

/home/ivan/ootbc/common/include/bitRow.hh:752: error: argument of type `size_t
(
bitRow<bool, 1u,  bigEndian>::)(bitReference<bool, 1u,  bigEndian>) const' does
not match `size_t'

Subsequent diagnostics are an ignorable cascade. The constructor is declared
as:

    template<size_t count>
                bitRow(bitArray<count, T, bitWidth, ordering>& a)
                    : start(&a[0]), length(count) {}

and the invocation is:

    bitArray<256, T, bitWidth, ordering>
                data;
    bitRow_t    bd(data);

which appears innocuous. The type reported in the diagnostic seems completely
bogus to me, and I think that the code is valid in its context :-)


-- 
           Summary: bizarre diagnostic on valid (?) constructor
           Product: gcc
           Version: 3.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: igodard at pacbell dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] bizarre diagnostic on valid (?) constructor

[igodard at pacbell dot net]

------- Comment #2 from igodard at pacbell dot net  2005-11-03 15:36 -------
Created an attachment (id=10128)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10128&action=view)
source code (compressed)


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] bizarre diagnostic on valid (?) constructor

[igodard at pacbell dot net]

------- Comment #1 from igodard at pacbell dot net  2005-11-03 15:36 -------
Created an attachment (id=10127)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=10127&action=view)
compiler output


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] bizarre diagnostic on valid (?) constructor

[igodard at pacbell dot net]

------- Comment #3 from igodard at pacbell dot net  2005-11-03 16:43 -------
Here's a reduced case:

template<int x> struct B {};

struct A {
    template<int i>
        A(const B<i>& b) : j(i) {}
    void    i() {}
int     j;
        };

int main() {
    B<5> b;
    A a(b);
    }

which gets you:

~/ootbc/members/src$ g++ foo.cc
foo.cc: In constructor `A::A(const B<i>&) [with int i = 5]':
foo.cc:12:   instantiated from here
foo.cc:5: error: argument of type `void (A::)()' does not match `int'

The compiler is picking up the member function "i" as the initializer for "j",
rather than the template argument "i". (In the original the template argument
"count" similarly matched a member function name). Yet it has the right "i" in
the constructor's argument type "B<i>", or there would have been an earlier
error.

FWIW, Comeau accepts this code.

Ivan


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] [3.4/4.0/4.1 Regression] bizarre diagnostic on valid (?) constructor

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2005-11-03 17:04 -------
I tested a few different versions of gcc and added the results to known to
work/fail.  3.3.3 accepted this code.  before in 3.2.3 (and below), the error
message was :
t.cc:6: declaration of `void A::i()'
t.cc:4: changes meaning of `i' from `int i'


I don't know if this is valid or not, the issue is a namelookup issue.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|2.95.3 3.0.4 3.4.0 4.0.0    |2.95.3 3.0.4 3.4.0 4.0.0
                   |4.1.0                       |4.1.0 3.2.3
            Summary|bizarre diagnostic on valid |[3.4/4.0/4.1 Regression]
                   |(?) constructor             |bizarre diagnostic on valid
                   |                            |(?) constructor
   Target Milestone|---                         |4.0.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] [3.4/4.0/4.1 Regression] bizarre diagnostic on valid (?) constructor

[bangerth at dealii dot org]

------- Comment #5 from bangerth at dealii dot org  2005-11-08 05:14 -------
This can of course be made even simpler:
----------------
struct A {
    template<int i> A(int (*)[i]) : j(i) {}
    int * i;
    int   j;
};

int i[3];
A a(&i);
----------------

g/x> /home/bangerth/bin/gcc-3.4.5-pre/bin/c++ -c x.cc
x.cc: In constructor `A::A(int (*)[i]) [with int i = 3]':
x.cc:8:   instantiated from here
x.cc:2: error: invalid conversion from `int*' to `int'

I'm pretty sure I've seen this somewhere before -- the question was indeed
which name should be looked up, the template name or the name of a member
variable.

In any case, the error message is not particularly helpful, and I know of
at least one other compiler that accepts this.

W.


-- 

bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2005-11-08 05:14:36
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] [3.4/4.0/4.1 Regression] bizarre diagnostic when a member variable and a template parameter have the same name

[bangerth at dealii dot org]

------- Comment #6 from bangerth at dealii dot org  2005-11-08 05:23 -------
This is PR 13967. See in particular comment #11 in the audit trail there.

Not that that PR would be particularly enlightening, but the situation is
at least discussed at length there.

W.

*** This bug has been marked as a duplicate of 13967 ***


-- 

bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657

[Bug c++/24657] [3.4/4.0/4.1 Regression] bizarre diagnostic when a member variable and a template parameter have the same name

[gdr at integrable-solutions dot net]

------- Comment #7 from gdr at integrable-solutions dot net  2005-11-16 19:14 -------
Subject: Re:  [3.4/4.0/4.1 Regression] bizarre diagnostic on valid (?)
constructor

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

| I'm pretty sure I've seen this somewhere before -- the question was indeed
| which name should be looked up, the template name or the name of a member
| variable.

Indeed this is an issue.  Discussion in on the -core reached the
consensus that we could change the lookup rules for member templates
so that template parameters for *member* templates  would be searched,
before members of the enclosing class. But I don't recall the issue
has attained an advanced state yet.  Note that in the older "issue",
there actually are TWO separate issues.

-- Gaby


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=24657