Re: c++/7345: parse error when using templated member function from templated base class

Re: c++/7345: parse error when using templated member function from templated base class

[lerdsuwa]

Synopsis: parse error when using templated member function from templated base class

State-Changed-From-To: open->closed
State-Changed-By: lerdsuwa
State-Changed-When: Sat Jul 20 09:13:38 2002
State-Changed-Why:
    Not a bug.  Use the following syntax
      A<x>::template foo<2>()
    Here 'foo<2>' is a function inside a base class that
    depends on the template parameter 'x'.  So the prefix
    'A<x>::' is required.  With the prefix, '<' will be treated
    as a less-than operator (not the beginning of template 
    argument) unless the 'template' keyword appears
    before 'foo<2>'.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=7345

c++/7345: parse error when using templated member function from templated base class

[ronny]

>Number:         7345
>Category:       c++
>Synopsis:       parse error when using templated member function from templated base class
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Wed Jul 17 12:46:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Ronny Krashinsky
>Release:        gcc version 3.0.4
>Organization:
>Environment:
x86, linux
>Description:
compiling this program:
-----------------------------------------------------
//#include<stdio.h>

template<int x>
class A {
public:
  template<int y>
  int foo() { return (x + y); };
  int foo2() { return foo<2>(); };
};


template<int x>
class B : public A<x> {
public:
  int bar() { 
    return ( foo<2>() );
  };
};


int main() {
  int i;
  A<3> a;
  i = a.foo<2>();
  //printf("%d\n", i);
  i = a.foo2();
  //printf("%d\n", i);

  B<3> b;
  i = b.bar();
  //printf("%d\n", i);

  return(0);
};
-----------------------------------------------------

results in this parse error:
-----------------------------------------------------
bug.cc: In member function `int B<x>::bar()':
bug.cc:16: parse error before `;' token
-----------------------------------------------------

I think that the compiler is not recognizing foo<2> as the name of a function as it should.

I don't know of any workaround to call foo<2> from within B.  "A::foo<2>()" doesn't work, "using A::foo<2>" doesn't work, declaring a function pointer doesn't work, etc.
>How-To-Repeat:
compile the program
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="bug.cc"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="bug.cc"

Ly8jaW5jbHVkZTxzdGRpby5oPgoKdGVtcGxhdGU8aW50IHg+CmNsYXNzIEEgewpwdWJsaWM6CiAg
dGVtcGxhdGU8aW50IHk+CiAgaW50IGZvbygpIHsgcmV0dXJuICh4ICsgeSk7IH07CiAgaW50IGZv
bzIoKSB7IHJldHVybiBmb288Mj4oKTsgfTsKfTsKCgp0ZW1wbGF0ZTxpbnQgeD4KY2xhc3MgQiA6
IHB1YmxpYyBBPHg+IHsKcHVibGljOgogIGludCBiYXIoKSB7IAogICAgcmV0dXJuICggZm9vPDI+
KCkgKTsKICB9Owp9OwoKCmludCBtYWluKCkgewogIGludCBpOwogIEE8Mz4gYTsKICBpID0gYS5m
b288Mj4oKTsKICAvL3ByaW50ZigiJWRcbiIsIGkpOwogIGkgPSBhLmZvbzIoKTsKICAvL3ByaW50
ZigiJWRcbiIsIGkpOwoKICBCPDM+IGI7CiAgaSA9IGIuYmFyKCk7CiAgLy9wcmludGYoIiVkXG4i
LCBpKTsKCiAgcmV0dXJuKDApOwp9OwoKCgoKCg==