Zig Version

0.14.0-dev.3213+53216d2f2

Steps to Reproduce and Observed Behavior

Compile a Zig file that uses extern opaque and packed opaque types:

// foo.zig
const X = extern opaque {};
const Y = packed opaque {};

export fn foo(x: *X, y: *Y) void {
    _ = x;
    _ = y;
}

The build succeeds:

$ zig build-obj foo.zig
$ echo $?
0
$ ls foo.o
foo.o

Expected Behavior

This should be a compile error. extern and packed are meant to control a type's layout, so they make no sense to apply to an opaque type as those types have unknown layout.