stage3: optional slice to optional multi-item pointer coercion no longer works

[jcmoyer]

Zig Version

0.10.0-dev.3659+e5e6eb983

Steps to Reproduce

This may be an intended change, but I didn't see it mentioned in the upgrade guide. This used to compile:

const std = @import("std");

fn bar(s: ?[*:0]const u8) void {
    _ = s;
}

fn foo(s: ?[:0]const u8) void {
    bar(s orelse null);
}

pub fn main() !void {
    foo("hello");
}

Expected Behavior

It compiles.

Actual Behavior

It doesn't compile:

D:\Scratch\testfn\src\main.zig:8:11: error: expected type '?[*:0]const u8', found '?[:0]const u8'
    bar(s orelse null);
        ~~^~~~~~~~~~~
D:\Scratch\testfn\src\main.zig:8:11: note: optional type child '[:0]const u8' cannot cast into optional type child '[*:0]const u8'

[jcmoyer]

Sorry original code snippet did not actually reproduce the problem, I've updated it with one that does.

[nektro]

this also highlights a current nastyness when using optionals because ideally you could use something like Optional chaining and do s?.ptr

[iacore]

The type checker is right (I think).
Fix:
bar(if (s) |ss| ss.ptr else null);