Created attachment 208 [details]
an example

Including original attachment in this comments. Issue looks similar to BUG 918.

import std.stdio;

typedef char ctd;
class Foo { }
class Bar : Foo { }

void main()
{
    Baz!(char)(); /* regular template version used only because
                   * template alias parameters reject basic types. */
    Baz!(ctd)(); // alias version used
    Baz!(Foo)(); // Foo version used
    Baz!(Bar)(); // alias version used
}

void Baz(T)()
{
    writefln("regular template version called with ", T.stringof);
}

void Baz(T : Foo)()
{
    writefln("foo specialization called with ", T.stringof);
}

void Baz(alias T)()
{
    writefln("alias version called with ", T.stringof);
}

This problem is still present in DMD 2.039.
It looks that from unknown reasons bug918 is solved (nobody comented what was source of regression and dissapiring of it). Probably it is different aspect here of template matching.

Still happens with 2.064. The typedef part is no longer relevant as the language feature is going away, but the class hierarchy part remains.

Shorter test case:

class Foo { }
class Bar : Foo { }

void f(T : Foo)() { }
void f(alias T)() { assert(false); }

void main()
{
    f!Bar();
}

*** Issue 3137 has been marked as a duplicate of this issue. ***

https://github.com/D-Programming-Language/dmd/pull/3156

Fixed:
https://github.com/D-Programming-Language/dmd/commit/422bf8d8dc4c92ca86f301176c6592a1c1673b72

*** Issue 4431 has been marked as a duplicate of this issue. ***