Hi all,
Yesterday I ran into a g++ (3.4.6) compiler problem for code that I have
been compiling without a problem using the Intel (9.0) compiler. Here's a
code snippet that shows what happened:
template<typename A, typename B>
class Foo { };
struct Bar {
void method ( Foo<int,int> const& stuff = Foo<int,int>() );
};
The g++ compiler error is:
foo.cpp:5: error: expected `,' or `...' before '>' token
foo.cpp:5: error: wrong number of template arguments (1, should be 2)
foo.cpp:2: error: provided for `template<class A, class B> struct Foo'
foo.cpp:5: error: default argument missing for parameter 2 of `void
Bar::method(const Foo<int, int>&, int)'
Apparently, the default argument is not accepted when written this way,
and the compiler assumes that instead of the second template argument a
new function argument is specified, for which it then expects a default
value because the `stuff` argument has one. I can help the compiler by
creating a typedef, and then everything compiles fine:
template<typename A, typename B>
class Foo { };
struct Bar {
typedef Foo<int,int> FooType;
void method ( FooType const& stuff = FooType() );
};
So I can solve my problem, but I don't understand what is going on. Do I
miss a C++ (template?) language feature here and am I doing something
wrong, or is the g++ compiler wrong in not accepting the first piece of
code?
Note BTW that this also compiles ...
template<typename A, typename B>
class Foo { };
void method ( Foo<int,int> const& stuff = Foo<int,int>() );
>From stackoverflow, where I posted the exact same question, two other
people confirmed that they could compile the code with two other
compilers: IBM's xlC V7.0 and Comeau.
