[Bug c++/57] [DR 325] GCC can't parse a non-parenthesized comma in a template-id within a default argument

[prez at neuromancy dot net]

--- Additional Comments From prez at neuromancy dot net  2004-11-27 16:04 
---
(In reply to comment #21)
> *** Bug 18688 has been marked as a duplicate of this bug. ***

Is it really a dupe?  The bug I raised only involved a templated argument, the
class with the member function is not templated.  Besides which, if its invalid
as a member function, why is it not invalid stand-alone?  And why should
typedef's get around it?

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57

[Bug c++/18688] New: Default argument of a template class/struct function parse error.

[prez at neuromancy dot net]

My system info:

Configured with: /home/portage/portage/gcc-3.4.2-r2/work/gcc-3.4.2/configure
--enable-version-specific-runtime-libs --prefix=/usr
--bindir=/usr/i686-pc-linux-gnu/gcc-bin/3.4
--includedir=/usr/lib/gcc/i686-pc-linux-gnu/3.4.2/include
--datadir=/usr/share/gcc-data/i686-pc-linux-gnu/3.4
--mandir=/usr/share/gcc-data/i686-pc-linux-gnu/3.4/man
--infodir=/usr/share/gcc-data/i686-pc-linux-gnu/3.4/info
--with-gxx-include-dir=/usr/lib/gcc/i686-pc-linux-gnu/3.4.2/include/g++-v3
--host=i686-pc-linux-gnu --enable-nls --without-included-gettext
--enable-__cxa_atexit --enable-clocale=gnu --enable-shared --with-system-zlib
--disable-checking --disable-werror --disable-libunwind-exceptions --with-gnu-ld
--enable-threads=posix --disable-multilib --disable-libgcj 
--enable-languages=c,c++
Thread model: posix
gcc version 3.4.2  (Gentoo Linux 3.4.2-r2, ssp-3.4.1-1, pie-8.7.6.5)

The following code failes to compile (compiles with "g++ -o blah blah.cpp"):

#include 
#include 
 
template
struct other_sort : public std::binary_function
{
bool operator()(const T &lhs, const T &rhs) const { return lhs < rhs; }
};
 
// Works just fine
void f(const std::set > &in =
 std::set >())
{
}
 
struct test1
{
// Parser error
void f(const std::set > &in =
 std::set >()) const
{
}
 
// Works just fine.
void g(const std::set > &in) const
{
}
};
 
struct test2
{
typedef other_sort sort_td;
 
// Parser error
void f(const std::set &in =
 std::set()) const
{
}
 
// Works just fine.
void g(const std::set &in) const
{
}
};
 
struct test3
{
typedef std::set > set_td;
 
// Works just fine.
void f(const set_td &in = set_td()) const
{
}
 
// Works just fine.
void g(const set_td &in) const
{
}
};
 
int main()
{
test1 x;
x.f();
test2 y;
y.f();
test3 z;
z.f();
return 0;
}

With the following errors:

blah.cpp:20: error: expected `,' or `...' before '>' token
blah.cpp:20: error: missing `>' to terminate the template argument list
blah.cpp:20: error: template argument 1 is invalid
blah.cpp:20: error: template argument 2 is invalid
blah.cpp:20: error: template argument 3 is invalid
blah.cpp:36: error: expected `,' or `...' before '>' token
blah.cpp:36: error: missing `>' to terminate the template argument list
blah.cpp:36: error: template argument 1 is invalid
blah.cpp:36: error: template argument 2 is invalid
blah.cpp:36: error: template argument 3 is invalid
blah.cpp: In function `int main()':
blah.cpp:64: error: no matching function for call to `test1::f()'
blah.cpp:21: note: candidates are: void test1::f(const std::set, std::allocator >&,
other_sort) const
blah.cpp:66: error: no matching function for call to `test2::f()'
blah.cpp:37: note: candidates are: void test2::f(const std::set, std::allocator >&,
other_sort) const

I can post the assembly code if you REALLY want, however I've tried this with
gcc 3.3.4 and gcc 3.4.2, and all the code above is using all the standard STL
that comes with those distributions, without modification.

As you can see from the above comments, if I typedef the set, it works fine.

-- 
   Summary: Default argument of a template class/struct function
parse error.
   Product: gcc
   Version: 3.4.2
Status: UNCONFIRMED
          Severity: normal
  Priority: P2
 Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: prez at neuromancy dot net
CC: gcc-bugs at gcc dot gnu dot org
  GCC host triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18688