Hello all,
Following (bit weird ;-) code shows weird case of variadic template
function specialization, however I am not sure it is legal, (atleast I
haven't found any wording that would prevent such use):
enum SelectFoo {S1, S2, S3};
struct A
{
template <SelectFoo Selector_, typename... Args_ >
void foo (Args_...);
};
template <> void
A::foo<S1> (int) {} // #1 compiles fine
template <> void
A::foo<S2> () {} // #2 this won't compile (error: template-id
'foo<(SelectFoo)1u>' for 'void A::foo()' does not match any template
declaration)
template <> void
A::foo<S3> (int, int) {} // #3 this won't compile too (error:
template-id 'foo<(SelectFoo)2u>' for 'void A::foo(int, int)' does not
match any template declaration)
I have checked this code with g++-4.3.2 and g++-4.4.0-alpha20081010
(gentoo ebuild)
It seems that variadic type pack Args_... is always treated as one parameter.
When I have tried declaration like:
template <SelectFoo, typename T_, typename... More_>
void foo (T_, More_...);
it could match specialization with two parameters only, 'foo(int,
int)' in this example.
If I would provide all three declarations ie.
struct A
{
template <SelectFoo>
void foo ();
template <SelectFoo, typename T_>
void foo (T_);
template <SelectFoo, typename T1_, typename T2_>
void foo (T1_, T2_);
};
everything compiles fine, with both gcc and Comeau C/C++ online, as
one would expect.
My question is: whether all specializations (#1, #2, #3) should be accept,
or it is just illegal use of variadic templates not reported here, and
#1 is accepted incorrectly,
or this is expected result?
Piotr
