`error: unreachable code` breaks noreturn case in generic context

[vi]

const assert = @import("std").debug.assert;
const warn = @import("std").debug.warn;

fn v(comptime T:type, vv: fn()T)T {
    const L = struct {
        fn a(vv2:fn()T) T {
            return vv2();
        }

        fn b(vv1:fn()T) T {
            return a(vv1);
        }
    };
    return L.b(vv);
}

fn voidy() void {

}

fn noreturny() noreturn {
    while(true){}
}

test "noreturny?" {
    v(void, voidy);
    v(noreturn, noreturny);
}

/tmp/emb/test.zig:14:5: error: unreachable code
    return L.b(vv);

"unreachable code" in general looks like a lint aiming for clean code, not a hard error preventing compilation.

There should be either

• Ignoring code being unreachable only because of noreturn coming from generic T
• Explicit suppressing of unreachable code check.

[vi]

Like #224 , unreachable code error should be degradable to warning both temporarily globally (--sloppy mode) and permanently individually (in this case with no warning).

[andrewrk]

Related: #2198