https://issues.dlang.org/show_bug.cgi?id=24255

basile-z <b2.temp@gmx.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |b2.temp@gmx.com

--- Comment #1 from basile-z <b2.temp@gmx.com> ---
Took me a while to get that but I think that in `void function(T)` it's not the
same `T` as in `void fun(T)`

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https://issues.dlang.org/show_bug.cgi?id=24255

--- Comment #2 from basile-z <b2.temp@gmx.com> ---
to be more clear

```
void fun(T)(T t, void function(T) f) {}

void argOK(int){}
void argNG(OtherT)(OtherT ot){}

void main()
{
    fun(123, &argOK);
    fun(123, &argNG); // semantically equivalent to the original test case
}
```

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https://issues.dlang.org/show_bug.cgi?id=24255

Paul Backus <snarwin+bugzilla@gmail.com> changed:

           What    |Removed                     |Added
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           Severity|normal                      |enhancement

--- Comment #3 from Paul Backus <snarwin+bugzilla@gmail.com> ---
Yes, in the current implementation of the DMD frontend, the compiler performs semantic analysis on the argument `(x) {}` *before* it attempts to deduce the template argument `T`, and as a result, it determines that `(x) {}` is template lambda.

However, there is nothing in the language spec that requires the DMD frontend to behave this way. In your example, argNG can *only* be a template, because it is explicitly declared as one. But in the original example, the lambda expression `(x) {}` is ambiguous: it could be a template, or it could be a `void function(int)`.

Given that the language spec gives the compiler the freedom to interpret `(x) {}` either way, I think it's reasonable to request that the compiler choose the more useful interpretation.

Of course, by the same logic, we can't say that the current behavior is *wrong*, so I'll change this to an enhancement request.

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https://issues.dlang.org/show_bug.cgi?id=24255

--- Comment #4 from basile-z <b2.temp@gmx.com> ---
I agree over the fact that this is an enhancement request.

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