diff --git a/src/bootstrap.zig b/src/bootstrap.zig
index 5296927..b133ddb 100644
--- a/src/bootstrap.zig
+++ b/src/bootstrap.zig
@@ -5472,7 +5472,10 @@ pub const Module = struct {
     pub fn check_types(module: *Module, expected_type: *Type, source_type: *Type) void {
         if (expected_type != source_type) {
             const dst_p_src_i = expected_type.bb == .pointer and source_type.bb == .integer;
-            const result = dst_p_src_i;
+            const dst_alias_src_not = expected_type.bb == .alias and expected_type.bb.alias.type == source_type;
+            const src_alias_dst_not = source_type.bb == .alias and source_type.bb.alias.type == expected_type;
+            const both_alias_to_same_type = expected_type.bb == .alias and source_type.bb == .alias and expected_type.bb.alias.type == source_type.bb.alias.type;
+            const result = dst_p_src_i or dst_alias_src_not or src_alias_dst_not or both_alias_to_same_type;
             if (!result) {
                 module.report_error();
             }
diff --git a/src/compiler.bbb b/src/compiler.bbb
index 52f2bac..de1949f 100644
--- a/src/compiler.bbb
+++ b/src/compiler.bbb
@@ -1,9 +1,45 @@
 mode_t = typealias u64;
+int = typealias s32;
+usize = typealias u64;
+File = typealias s32;
 
-[extern] memcmp = fn [cc(c)] (a: &u8, b: &u8, byte_count: u64) s32;
+OAccessMode = enum u2
+{
+    read_only = 0,
+    write_only = 1,
+    read_write = 2,
+}
+
+O = bits u32
+{
+    access_mode: OAccessMode,
+    _: u4,
+    creat: u1,
+    excl: u1,
+    noctty: u1,
+    trunc: u1,
+    append: u1,
+    nonblock: u1,
+    dsync: u1,
+    async: u1,
+    direct: u1,
+    _: u1,
+    directory: u1,
+    nofollow: u1,
+    noatime: u1,
+    cloexec: u1,
+    sync: u1,
+    path: u1,
+    tmpfile: u1,
+    _: u9,
+}
+
+[extern] memcmp = fn [cc(c)] (a: &u8, b: &u8, byte_count: usize) int;
 [extern] memcpy = fn [cc(c)] (destination: &u8, source: &u8, byte_count: u64) &u8;
-[extern] exit = fn [cc(c)] (exit_code: s32) noreturn;
-[extern] mkdir = fn [cc(c)] (path: &u8, mode: mode_t) s32;
+[extern] exit = fn [cc(c)] (exit_code: int) noreturn;
+
+[extern] mkdir = fn [cc(c)] (path: &u8, mode: mode_t) int;
+[extern] open = fn [cc(c)] (path: &u8, o: O, ...) int;
 
 assert = fn (ok: u1) void
 {
@@ -177,6 +213,55 @@ os_make_directory = fn (path: &u8) void
     >result = mkdir(path, 0o755);
 }
 
+OpenFlags = bits
+{
+    truncate: u1,
+    execute: u1,
+    write: u1,
+    read: u1,
+    create: u1,
+    directory: u1,
+}
+
+OpenPermissions = bits
+{
+    read: u1,
+    write: u1,
+    execute: u1,
+}
+
+os_file_open = fn (path: &u8, flags: OpenFlags, permissions: OpenPermissions) File
+{
+    >access_mode: OAccessMode = undefined;
+    if (flags.read and flags.write)
+    {
+        access_mode = .read_write;
+    }
+    else if (flags.read)
+    {
+        access_mode = .read_only;
+    }
+    else if (flags.write)
+    {
+        access_mode = .write_only;
+    }
+    else
+    {
+        unreachable;
+    }
+
+    >o: O = {
+        .access_mode = access_mode,
+        .trunc = flags.truncate,
+        .creat = flags.create,
+        .directory = flags.directory,
+    };
+
+    >mode: mode_t = #select(permissions.execute, 0o755, 0o644);
+    >fd = open(path, o, mode);
+    return fd;
+}
+
 Arena = struct
 {
     reserved_size: u64,
@@ -288,6 +373,11 @@ arena_join_string = fn (arena: &Arena, pieces: [][]u8) []u8
     return pointer[..size];
 }
 
+file_read = fn (arena: &Arena, path: []u8) []u8
+{
+    >fd = os_file_open(path.pointer, { .read = 1 }, { .read = 1 });
+}
+
 GlobalState = struct
 {
     arena: &Arena,
@@ -371,6 +461,19 @@ compile_file = fn (arena: &Arena, compile: CompileFile) void
         "_",
         #select(compile.has_debug_info, "di", "nodi"),
     ][..]);
+
+    os_make_directory(base_cache_dir.pointer);
+    if (is_compiler)
+    {
+        >compiler_dir = arena_join_string(arena, [ base_cache_dir, "/compiler" ][..]);
+        os_make_directory(compiler_dir.pointer);
+    }
+    os_make_directory(outputh_path_dir.pointer);
+
+    >outputh_path_base = arena_join_string(arena, [ outputh_path_dir, "/", base_name ][..]);
+
+    >output_object_path = arena_join_string(arena, [ outputh_path_base, ".o" ][..]);
+    >output_executable_path = outputh_path_base;
 }
 
 [export] main = fn [cc(c)] (argument_count: u32, argv: &&u8) s32