[Issue 20190] New: Deprecation not triggered on templates

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=20190

          Issue ID: 20190
           Summary: Deprecation not triggered on templates
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: critical
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: pro.mathias.lang at gmail.com

```
deprecated template Const (T)
{
    deprecated alias Const = const(T);
}
void foo(Const!(char)[]) {}
```

This should print a deprecation message.
The double deprecated shouldn't be necessary either.
Yet, as of 2.087.1, there's no output.

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