[Issue 798] New: Template function overloading problems

[Sean Kelly]

Template functions cannot be overloaded with normal functions.  This is 
by design.

d-bugmail at puremagic.com wrote:
> 
> class Test {
>     static void func(T)(T v) {}
> //    static void func() {}                //Error! Solution: static void
> func()() {}
> //    static void func(int i, float f) {}  //Error! Solution: static void
> func()(int i, float f) {}

static void func(T)(T v) {}
static void func()() {}
static void func(T1=void, T2=void)() {}

>     static void opCall(T)(T t) {}
>     static void opCall()() {}
>     //Below line in fact conflicts with opCall()() as commenting it solves
> problem - no workaround known
>     //static void opCall()(int i, float f) {}

Same as above.  Templates with the same name and same number of 
templates parameters cannot be overloaded unless one is a specialization 
of the other.  ie.

static void func(T, U)(T v1, U v2) {}
static void func(T, U)(T v1, U v2, int v3) {}

Doesn't work.  But:

static void func(T, U)(T v1, U v2) {}
static void func(T, U : double)(T v1, U v2, int v3) {}

Works.  The way around this problem is to add dummy template parameters 
to alter the template parameter count to avoid unwanted collisions:

static void func(T, U)(T v1, U v2) {}
static void func(T, U, V=void)(T v1, U v2, int v3) {}

In the above, V is unused and serves only to change the name mangling of 
the second template function.


Sean