1 files changed, 48 insertions, 0 deletions
diff --git a/lang/zig/align.zig b/lang/zig/align.zig
new file mode 100644
index 0000000..b81740a
--- /dev/null
+++ b/lang/zig/align.zig
@@ -0,0 +1,48 @@
+const arch = std.Target.current.cpu.arch;
+const bytesAsSlice = std.mem.bytesAsSlice;
+const expect = std.testing.expect;
+const sliceAsBytes = std.mem.sliceAsBytes;
+const std = @import("std");
+
+test "variable alignment" {
+    var x: i32 = 1234;
+    const align_of_i32 = @alignOf(@TypeOf(x));
+    expect(@TypeOf(&x) == *i32);
+    expect(*i32 == *align(align_of_i32) i32);
+    if (arch == .x86_64)
+        expect(@typeInfo(*i32).Pointer.alignment == 4);
+}
+
+var foo: u8 align(4) = 100;
+
+test "global variable alignment" {
+    expect(@typeInfo(@TypeOf(&foo)).Pointer.alignment == 4);
+    expect(@TypeOf(&foo) == *align(4) u8);
+    const as_pointer_to_array: *[1]u8 = &foo;
+    const as_slice: []u8 = as_pointer_to_array;
+    expect(@TypeOf(as_slice) == []align(4) u8);
+}
+
+fn derp() align(@sizeOf(usize) * 2) i32 { return 1234; }
+fn noop1() align(1) void {}
+fn noop4() align(4) void {}
+
+test "function alignment" {
+    expect(derp() == 1234);
+    expect(@TypeOf(noop1) == fn() align(1) void);
+    expect(@TypeOf(noop4) == fn() align(4) void);
+    noop1();
+    noop4();
+}
+
+test "pointer alignment safety" {
+    var array align(4) = [_]u32{ 0x11111111, 0x11111111 };
+    const bytes = sliceAsBytes(array[0..]);
+    expect(bar(bytes) == 0x11111111);
+}
+
+fn bar(bytes: []u8) u32 {
+    const slice4 = bytes[1..5];
+    const int_slice = bytesAsSlice(u32, @alignCast(4, slice4));
+    return int_slice[0];
+}