Struct containing generic member over slice of Self fails to compile

[ifreund]

This code fails to compile with the following error:

const std = @import("std");

fn Frog(comptime T: type) type {
    return struct { fish: T };
}

const Bear = struct {
    grizzle: Frog([]Bear),
};

pub fn main() !void {
    const my_precious = Bear{ .grizzle = undefined };
    std.debug.warn("{}", .{my_precious});
}

./src/main.zig:9:14: error: struct 'Bear' depends on itself
const Bear = struct {
             ^
./src/main.zig:10:19: note: referenced here
    grizzle: Frog([]Bear),
                  ^
./src/main.zig:10:18: note: referenced here
    grizzle: Frog([]Bear),
                 ^
./src/main.zig:15:29: note: referenced here
    const my_precious = Bear{
                            ^
/usr/lib/zig/std/start.zig:253:40: note: referenced here
            const result = root.main() catch |err| {
                                       ^

However, a small change which should produce identical code allows it to compile

const std = @import("std");

fn Frog(comptime T: type) type {
    return struct { fish: []T };
}

const Bear = struct {
    grizzle: Frog(Bear),
};

pub fn main() !void {
    const my_precious = Bear{ .grizzle = undefined };
    std.debug.warn("{}", .{my_precious});
}

In the second example Instead of passing a slice type to Frog, the struct returned by Frog always contains a slice. The first example which fails to compile is valid code as only a pointer to Bear is stored, not the struct itself, so it should be allowed to compile.

[Vexu]

Fixed in self-hosted, tested in test/behavior/struct.zig:test "no dependency loop on optional field wrapped in generic function".