@safe function causes attribute inference since 2.072

[Steven Schveighoffer]

I'm trying to fix a bug in phobos, and I was perplexed when the type I 
defined inferred  constructor attributes in my unittest. It looks like this:


@safe unittest
{
    static struct A
    {
       int x;
       this(scope ref return const A other) {}
    }
}

I was surprised that the copy constructor is further inferred to be 
pure, @nogc, nothrow.

I actually wanted it to be not inferred because that is part of the bug 
I'm fixing. After much head scratching, I discovered that it's the @safe 
tag on the unit test.

Observe:

void foo1()
{
   static struct S { void bar() {} }
   pragma(msg, typeof(S.bar)); // void()
}

@safe void foo2()
{
   static struct S { void bar() {} }
   pragma(msg, typeof(S.bar)); // pure nothrow @nogc @safe void()
}

It has been this way since 2.072 (prior to that, foo2.S.bar is just 
@safe void()). I don't see a changelog that shows this to be intended.

Should this be a bug? I think at least the fact that inference only 
happens on structs inside @safe functions doesn't make sense (why not 
pure, @nogc nothrow functions).

But if we "fix" the bug, we risk breaking a lot of code.

-Steve