Fix issue 23142 - Scope should not apply to unittests

[dkorpel]

Ignore scope when it doesn't apply instead of raising an error, similar to other attributes.

[dlang-bot]

Thanks for your pull request and interest in making D better, @dkorpel! We are looking forward to reviewing it, and you should be hearing from a maintainer soon.
Please verify that your PR follows this checklist:

• My PR is fully covered with tests (you can see the coverage diff by visiting the details link of the codecov check)
• My PR is as minimal as possible (smaller, focused PRs are easier to review than big ones)
• I have provided a detailed rationale explaining my changes
• New or modified functions have Ddoc comments (with Params: and Returns:)

Please see CONTRIBUTING.md for more information.

---

If you have addressed all reviews or aren't sure how to proceed, don't hesitate to ping us with a simple comment.

Bugzilla references

Auto-close	Bugzilla	Severity	Description
✓	23142	enhancement	Scope should not apply to unittests

Testing this PR locally

If you don't have a local development environment setup, you can use Digger to test this PR:

dub run digger -- build "master + dmd#14177"

[Geod24]

similar to other attributes.

Which ones ? const and immutable both error out. Yes they are STC and not type ctor, but they apply to the implicit this, and IMO that makes them closer to scope.

[dkorpel]

Which ones ?

pragma(inline, true) int x;
@nogc int y;
scope int z;
alias x = __gshared int;

[Geod24]

But not for functions?

[dkorpel]

But not for functions?

__gshared void f() {}
static void g() {}
final void h() {}

[rikkimax]

Okay, experiment time:

Only one of these error out.

struct Thing1 {
@safe scope:
    static void func() { // onlineapp.d(7): Error: function `onlineapp.Thing1.func` functions cannot be `scope`
    }
    
    unittest {
    }
}

struct Thing2 {
@safe const:
    static void func() {
    }
    
    unittest {
    }
}

struct Thing3 {
@safe immutable:
    static void func() {
    }
    
    unittest {
    }
}

struct Thing4 {
@safe shared:
    static void func() {
    }
    
    unittest {
    }
}