[Issue 16465] New: Template alias does not get unwrapped in templated functions

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16465

          Issue ID: 16465
           Summary: Template alias does not get unwrapped in templated
                    functions
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: sky.13th.95 at gmail.com

OK, here the situation:

For example, We have this template:
```
struct TestType( T )
{
    T data;
}
```

Then We added an alias on it:
`alias TestAlias( T ) = TestType!T;`

And from here strange things begins.
If We will use original name (TestType), it will feel OK:
```
void testFunctionA( T )( TestType!T arg )
{
    writeln( arg );
}
```

But if We will use an alias, in a function declaration, 
it will cause compile time error:
```
void testFunctionA( T )( TestAlias!T arg )
{
    writeln( arg );
}
```

```
Error: 
template test.testFunctionB cannot deduce function 
from argument types !()(TestType!int), 
candidates are:
    test.testFunctionB(T)(TestAlias!T arg)
```

As far as I understand this situation(I don't know how it really is),
compiler see this alias declaration something like this:
```
template TestAlias( T ) 
{
    alias TestAlias = TestType!T;
}
```

So on this stage it might understand it like a separate type(?), rather then
alias on existing one.

Compiler v2.071.0

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