zig/test/behavior/bugs/12928.zig

const std = @import("std");
const builtin = @import("builtin");
const expect = std.testing.expect;

const A = extern struct {
    value: *volatile B,
};
const B = extern struct {
    a: u32,
    b: i32,
};

test {
    if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;

    var a: *A = undefined;
    try expect(@TypeOf(&a.value.a) == *volatile u32);
    try expect(@TypeOf(&a.value.b) == *volatile i32);
}

const C = extern struct {
    value: *volatile D,
};
const D = extern union {
    a: u32,
    b: i32,
};
test {
    if (builtin.zig_backend == .stage2_spirv64) return error.SkipZigTest;

    var c: *C = undefined;
    try expect(@TypeOf(&c.value.a) == *volatile u32);
    try expect(@TypeOf(&c.value.b) == *volatile i32);
}