diff --git a/src/analyze.cpp b/src/analyze.cpp
index 49f8e093a0..9afd4cedc8 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -362,8 +362,10 @@ TypeTableEntry *get_pointer_to_type_extra(CodeGen *g, TypeTableEntry *child_type
     } else {
         assert(bit_offset == 0);
         parent_pointer = &child_type->pointer_parent[(is_const ? 1 : 0)];
-        if (*parent_pointer)
+        if (*parent_pointer) {
+            assert((*parent_pointer)->data.pointer.alignment == byte_alignment);
             return *parent_pointer;
+        }
     }
 
     type_ensure_zero_bits_known(g, child_type);
@@ -1240,16 +1242,16 @@ static bool type_allowed_in_extern(CodeGen *g, TypeTableEntry *type_entry) {
         case TypeTableEntryIdPointer:
             return type_allowed_in_extern(g, type_entry->data.pointer.child_type);
         case TypeTableEntryIdStruct:
-            return type_entry->data.structure.layout == ContainerLayoutExtern;
+            return type_entry->data.structure.layout == ContainerLayoutExtern || type_entry->data.structure.layout == ContainerLayoutPacked;
         case TypeTableEntryIdMaybe:
             {
                 TypeTableEntry *child_type = type_entry->data.maybe.child_type;
                 return child_type->id == TypeTableEntryIdPointer || child_type->id == TypeTableEntryIdFn;
             }
         case TypeTableEntryIdEnum:
-            return type_entry->data.enumeration.layout == ContainerLayoutExtern;
+            return type_entry->data.enumeration.layout == ContainerLayoutExtern || type_entry->data.enumeration.layout == ContainerLayoutPacked;
         case TypeTableEntryIdUnion:
-            return type_entry->data.unionation.layout == ContainerLayoutExtern;
+            return type_entry->data.unionation.layout == ContainerLayoutExtern || type_entry->data.unionation.layout == ContainerLayoutPacked;
     }
     zig_unreachable();
 }
@@ -1376,6 +1378,10 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
     fn_type_id.return_type = (fn_proto->return_type == nullptr) ?
         g->builtin_types.entry_void : analyze_type_expr(g, child_scope, fn_proto->return_type);
 
+    if (type_is_invalid(fn_type_id.return_type)) {
+        return g->builtin_types.entry_invalid;
+    }
+
     if (fn_type_id.cc != CallingConventionUnspecified && !type_allowed_in_extern(g, fn_type_id.return_type)) {
         add_node_error(g, fn_proto->return_type,
                 buf_sprintf("return type '%s' not allowed in function with calling convention '%s'",
@@ -1386,7 +1392,7 @@ static TypeTableEntry *analyze_fn_type(CodeGen *g, AstNode *proto_node, Scope *c
 
     switch (fn_type_id.return_type->id) {
         case TypeTableEntryIdInvalid:
-            return g->builtin_types.entry_invalid;
+            zig_unreachable();
 
         case TypeTableEntryIdUndefLit:
         case TypeTableEntryIdNullLit:
@@ -2352,6 +2358,7 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
     bool create_enum_type = decl_node->data.container_decl.auto_enum || (enum_type_node == nullptr && want_safety);
     bool *covered_enum_fields;
     ZigLLVMDIEnumerator **di_enumerators;
+    uint32_t abi_alignment_so_far;
     if (create_enum_type) {
         occupied_tag_values.init(field_count);
 
@@ -2373,7 +2380,7 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
         } else {
             tag_int_type = get_smallest_unsigned_int_type(g, field_count - 1);
         }
-        union_type->data.unionation.abi_alignment = get_abi_alignment(g, tag_int_type);
+        abi_alignment_so_far = get_abi_alignment(g, tag_int_type);
 
         tag_type = new_type_table_entry(TypeTableEntryIdEnum);
         buf_resize(&tag_type->name, 0);
@@ -2404,9 +2411,10 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
         }
         tag_type = enum_type;
         covered_enum_fields = allocate<bool>(enum_type->data.enumeration.src_field_count);
-        union_type->data.unionation.abi_alignment = get_abi_alignment(g, enum_type);
+        abi_alignment_so_far = get_abi_alignment(g, enum_type);
     } else {
         tag_type = nullptr;
+        abi_alignment_so_far = 0;
     }
     union_type->data.unionation.tag_type = tag_type;
 
@@ -2504,12 +2512,14 @@ static void resolve_union_zero_bits(CodeGen *g, TypeTableEntry *union_type) {
         uint32_t field_align_bytes = get_abi_alignment(g, field_type);
         if (field_align_bytes > biggest_align_bytes) {
             biggest_align_bytes = field_align_bytes;
-            if (biggest_align_bytes > union_type->data.unionation.abi_alignment) {
-                union_type->data.unionation.abi_alignment = biggest_align_bytes;
+            if (biggest_align_bytes > abi_alignment_so_far) {
+                abi_alignment_so_far = biggest_align_bytes;
             }
         }
     }
 
+    union_type->data.unionation.abi_alignment = abi_alignment_so_far;
+
     if (union_type->data.unionation.is_invalid)
         return;
 
diff --git a/std/os/zen.zig b/std/os/zen.zig
index f31d46e481..867bc6578f 100644
--- a/std/os/zen.zig
+++ b/std/os/zen.zig
@@ -42,7 +42,7 @@ pub fn map(v_addr: usize, p_addr: usize, size: usize, writable: bool) bool {
     return syscall4(SYS_map, v_addr, p_addr, size, usize(writable)) != 0;
 }
 
-pub fn createThread(function: fn()) u16 {
+pub fn createThread(function: fn()void) u16 {
     return u16(syscall1(SYS_createThread, @ptrToInt(function)));
 }
 
diff --git a/test/cases/misc.zig b/test/cases/misc.zig
index cfc3456738..85757efbb8 100644
--- a/test/cases/misc.zig
+++ b/test/cases/misc.zig
@@ -617,3 +617,19 @@ test "cold function" {
 fn thisIsAColdFn() void {
     @setCold(true);
 }
+
+
+const PackedStruct = packed struct { a: u8, b: u8, };
+const PackedUnion = packed union { a: u8, b: u32, };
+const PackedEnum = packed enum { A, B, };
+
+test "packed struct, enum, union parameters in extern function" {
+    testPackedStuff(
+        PackedStruct{.a = 1, .b = 2},
+        PackedUnion{.a = 1},
+        PackedEnum.A,
+    );
+}
+
+export fn testPackedStuff(a: &const PackedStruct, b: &const PackedUnion, c: PackedEnum) void {
+}
diff --git a/test/cases/struct.zig b/test/cases/struct.zig
index 7fb8421d6f..c3df97678b 100644
--- a/test/cases/struct.zig
+++ b/test/cases/struct.zig
@@ -404,3 +404,17 @@ test "native bit field understands endianness" {
     assert(bitfields.f6 == 0x6);
     assert(bitfields.f7 == 0x77);
 }
+
+test "align 1 field before self referential align 8 field as slice return type" {
+    const result = alloc(Expr);
+    assert(result.len == 0);
+}
+
+const Expr = union(enum) {
+    Literal: u8,
+    Question: &Expr,
+};
+
+fn alloc(comptime T: type) []T {
+    return []T{};
+}
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index cc28f29f26..fe167c472c 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -1,12 +1,16 @@
 const tests = @import("tests.zig");
 
 pub fn addCases(cases: &tests.CompileErrorContext) void {
-    cases.add("function with non-extern enum parameter",
+    cases.add("function with invalid return type",
+        \\export fn foo() boid {}
+    , ".tmp_source.zig:1:17: error: use of undeclared identifier 'boid'");
+
+    cases.add("function with non-extern non-packed enum parameter",
         \\const Foo = enum { A, B, C };
         \\export fn entry(foo: Foo) void { }
     , ".tmp_source.zig:2:22: error: parameter of type 'Foo' not allowed in function with calling convention 'ccc'");
 
-    cases.add("function with non-extern struct parameter",
+    cases.add("function with non-extern non-packed struct parameter",
         \\const Foo = struct {
         \\    A: i32,
         \\    B: f32,
@@ -15,7 +19,7 @@ pub fn addCases(cases: &tests.CompileErrorContext) void {
         \\export fn entry(foo: Foo) void { }
     , ".tmp_source.zig:6:22: error: parameter of type 'Foo' not allowed in function with calling convention 'ccc'");
 
-    cases.add("function with non-extern union parameter",
+    cases.add("function with non-extern non-packed union parameter",
         \\const Foo = union {
         \\    A: i32,
         \\    B: f32,