bug with tricky template example in gcc 3.0.2

[Andrew Pinski]

In GNU C++ version 3.1 20020201 (experimental):
Reading specs from /home/rodent/pinskia/gcc-linux/bin/../lib/gcc-
lib/i686-pc-linux-gnu/3.1/specs
Configured with: /lhome/src/gnu/gcc/gcc3.1/src/configure 
--prefix=/home/linux --with-gnu-as=/home/linux/bun/as --with-gnu-
ld=/home/linux/bin/ld --enable-threads=posix --enable-shared
Thread model: posix
gcc version 3.1 20020201 (experimental)

it looks to be fixed.

Thanks,
Andrew Pinski


On Saturday, February 2, 2002, at 11:03 , Nicolai Josuttis wrote:

> Hi,
>
> for our upcoming C++ templates book we wrote the tricky program
> to have named template arguments.
> As far as we know, this program is correct.
> However, gcc 3.0.2 prints a syntax error.
> Could you have a look at it, please
> adn give us feedback so that we might add a footnoe inside the
> book, if necessary?
>
> Thanks and best
>  Nico
>
> gcc -v:
> Reading specs from /local/gcc/rundir/lib/gcc-lib/i686-pc-linux-
> gnu/3.0.2/specs
> Configured with: /local/gcc/srcdir/configure --prefix /local/gcc/rundir
> --enable-languages=c++
> Thread model: single
> gcc version 3.0.2
>
> program:
> attached as namedtmpl.cpp
>
> call and output:
> /local/gcc/rundir/bin/g++ -g -ansi -W -Wall -Wwrite-strings 
> -Wstrict-prototypes
> -Wmissing-prototypes -Wtraditional -pedantic  -c namedtmpl.cpp
> namedtmpl.cpp: In member function `void BreadSlicer<PolicySetter1,
>    PolicySetter2, PolicySetter3, PolicySetter4>::print()':
> namedtmpl.cpp:88: parse error before `;' token
> make: *** [namedtmpl.o] Error 1
>
> --
> Nicolai M. Josuttis          	http://www.josuttis.de/
> Solutions in Time        	mailto:solutions@josuttis.de
> #include <iostream>
>
> // {PolicySelector<A,B,C,D> creates {A,B,C,D} as base classes}
> // - {Discriminator<> allows having even the same base class more than 
> once}
>
> template <typename Base, int D>
> class Discriminator : public Base {
> };
>
> template <typename Setter1, typename Setter2,
>           typename Setter3, typename Setter4>
> class PolicySelector : public Discriminator<Setter1,1>,
>                        public Discriminator<Setter2,2>,
>                        public Discriminator<Setter3,3>,
>                        public Discriminator<Setter4,4> {
> };
>
>
> // default policies
>
> class DefaultPolicy1 {};
> class DefaultPolicy2 {};
> class DefaultPolicy3 {
>   public:
>     static void doPrint() {
>         std::cout << "DefaultPolicy3::doPrint()\n";
>     }
> };
> class DefaultPolicy4 {};
>
>
> // define default policies as {P1, P2, P3, P4}
> class DefaultPolicies {
>   public:
>     typedef DefaultPolicy1 P1;
>     typedef DefaultPolicy2 P2;
>     typedef DefaultPolicy3 P3;
>     typedef DefaultPolicy4 P4;
> };
>
>
> // class to define a usage of the default policy values
> // - avoids ambiguities if we derive from {\tt DefaultPolicies more 
> than once}
> class DefaultPolicyArgs : virtual public DefaultPolicies {
> };
>
>
> // class templates to override the default policy values
>
> template <typename Policy>
> class Policy1_is : virtual public DefaultPolicies {
>   public:
>     typedef Policy P1;  // overriding typedef
> };
>
> template <typename Policy>
> class Policy2_is : virtual public DefaultPolicies {
>   public:
>     typedef Policy P2;  // overriding typedef
> };
>
> template <typename Policy>
> class Policy3_is : virtual public DefaultPolicies {
>   public:
>     typedef Policy P3;  // overriding typedef
> };
>
> template <typename Policy>
> class Policy4_is : virtual public DefaultPolicies {
>   public:
>     typedef Policy P4;  // overriding typedef
> };
>
>
> // create class template with four policies and default values
>
> template <typename PolicySetter1 = DefaultPolicyArgs,
>           typename PolicySetter2 = DefaultPolicyArgs,
>           typename PolicySetter3 = DefaultPolicyArgs,
>           typename PolicySetter4 = DefaultPolicyArgs>
> class BreadSlicer {
>     typedef PolicySelector<PolicySetter1, PolicySetter2,
>                            PolicySetter3, PolicySetter4>
>             Policies;
>     // use \T{Policies::P1, \T{Policies::P2}, ... to refer to the 
> various policies.}
>   public:
>     void print () {
>         Policies::P3::doPrint();
>     }
>     //...
> };
>
>
> // define a custom policy
> class CustomPolicy {
>   public:
>     static void doPrint() {
>         std::cout << "CustomPolicy::doPrint()\n";
>     }
> };
>
> int main()
> {
>     BreadSlicer<> bc1;
>     bc1.print();
>
>     BreadSlicer<Policy3_is<CustomPolicy> > bc2;
>     bc2.print();
> }