public inbox for gcc@gcc.gnu.org
 help / color / mirror / Atom feed
From: Simon MARTIN <simartin@users.sourceforge.net>
To: gcc@gcc.gnu.org
Subject: Type problem with template functions and inheritance ?
Date: Wed, 08 Sep 2004 20:10:00 -0000	[thread overview]
Message-ID: <200409082211.28678.simartin@users.sourceforge.net> (raw)

Hello.

I played a little with templates and template functions, and I encountered a 
problem with GCC while doing so. The code at the end of this message builds 
with Microsoft's Visual C++ Toolkit 2003, but fails with GCC. Since the code 
is quite "weird", I wonder whether there's a problem in GCC or Visual is too 
laxist.

What is strange is:
  - the "<unknown type>" in the error message
  - the fact that if I "help" GCC a little (before the first static_cast), 
then things work fine.

Thanks in advance for your help / explanation.

Regards,
Simon

[simon@texel gcc_test]$ g++ -v
Reading specs from /usr/lib/gcc-lib/i586-mandrake-linux-gnu/3.3.2/specs
Configured with: ../configure --prefix=/usr --libdir=/usr/lib 
--with-slibdir=/lib --mandir=/usr/share/man --infodir=/usr/share/info 
--enable-shared --enable-threads=posix --disable-checking --enable-long-long 
--enable-__cxa_atexit --enable-clocale=gnu 
--enable-languages=c,c++,ada,f77,objc,java,pascal 
--host=i586-mandrake-linux-gnu --with-system-zlib
Thread model: posix
gcc version 3.3.2 (Mandrake Linux 10.0 3.3.2-6mdk)

[simon@texel gcc_test]$ g++ -Wall -o test test.cpp
test.cpp: In function `int main(int, char**)':
test.cpp:18: error: invalid static_cast from type `<unknown type>' to type 
`bool (Base::*)(const char*)'

==== test.cpp
class Base {};
struct MyClass : public Base
{
  template<int key> bool Method(const char *value) { return true; }
};

int main(int argc, char *argv[])
{
  typedef bool (Base::*BaseMethodPtr)(const char*);
  typedef bool (MyClass::*MethodPtr)(const char*);

  MyClass aClass;

  MethodPtr mp = &MyClass::Method<1>;
  BaseMethodPtr p1 = static_cast<BaseMethodPtr>(mp);
  (aClass.*p1)("One");

  BaseMethodPtr p2 = static_cast<BaseMethodPtr>(&MyClass::Method<1>);
  (aClass.*p2)("OneAgain");

  return 0;
}
==== end of test.cpp

-- 
Kile - an Integrated LaTeX Environment for KDE
http://kile.sourceforge.net

             reply	other threads:[~2004-09-08 20:10 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-09-08 20:10 Simon MARTIN [this message]
2004-09-08 21:33 ` Vaclav Haisman
2004-09-08 22:41 Type problem with template functions and inheritance? Wolfgang Bangerth

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=200409082211.28678.simartin@users.sourceforge.net \
    --to=simartin@users.sourceforge.net \
    --cc=gcc@gcc.gnu.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).