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digitalmars.D.learn - Function Template Overloading

reply Q. Schroll <qs.il.paperinik gmail.com> writes:
void test(T)(T* arg);
void test(T)(ref T arg);

Let p be any pointer. Why is test(p) not an ambiguity error? Why 
is the second overload chosen?
Making the first one take auto ref T* lets the compiler choose 
the first.
Making the second one non-ref lets the compiler give me an 
ambiguity error.

Template Functions are not mentioned in the spec, at least not on 
https://dlang.org/spec/function.html#function-overloading, but it 
suggests that ref should not make the decision if it can be bound 
to.
Mar 14
parent reply ketmar <ketmar ketmar.no-ip.org> writes:
Q. Schroll wrote:

 void test(T)(T* arg);
 void test(T)(ref T arg);

 Let p be any pointer. Why is test(p) not an ambiguity error? Why is the 
 second overload chosen?
'cause `ref T` is more generic than `T*`. think of it as "greedy matching": compiler first tries to match `int*`, and if that failed, it tries `int`, for example. and `int*` matches the second template, so compiler choosing it.
Mar 14
parent Q. Schroll <qs.il.paperinik gmail.com> writes:
On Wednesday, 15 March 2017 at 02:33:36 UTC, ketmar wrote:
 Q. Schroll wrote:

 void test(T)(T* arg);
 void test(T)(ref T arg);

 Let p be any pointer. Why is test(p) not an ambiguity error? 
 Why is the second overload chosen?
'cause `ref T` is more generic than `T*`. think of it as "greedy matching": compiler first tries to match `int*`, and if that failed, it tries `int`, for example. and `int*` matches the second template, so compiler choosing it.
Wouldn't it be better vice versa, the more specific pattern to be prioritized? And as it actually *can* match both, is it a compiler-bug not to be an ambiguity error?
Mar 14