Add `string16` and `cstring16` (UTF-16 based strings)

18 files changed, 600 insertions, 60 deletions

diff --git a/src/build_settings.cpp b/src/build_settings.cpp
index 46a4f9ae5..40bbe41e5 100644
--- a/src/build_settings.cpp
+++ b/src/build_settings.cpp
@@ -1089,7 +1089,7 @@ gb_internal String internal_odin_root_dir(void) {
 	text = gb_alloc_array(permanent_allocator(), wchar_t, len+1);
 
 	GetModuleFileNameW(nullptr, text, cast(int)len);
-	path = string16_to_string(heap_allocator(), make_string16(text, len));
+	path = string16_to_string(heap_allocator(), make_string16(cast(u16 *)text, len));
 
 	for (i = path.len-1; i >= 0; i--) {
 		u8 c = path[i];
@@ -1387,14 +1387,14 @@ gb_internal String path_to_fullpath(gbAllocator a, String s, bool *ok_) {
 
 	mutex_lock(&fullpath_mutex);
 
-	len = GetFullPathNameW(&string16[0], 0, nullptr, nullptr);
+	len = GetFullPathNameW(cast(wchar_t *)&string16[0], 0, nullptr, nullptr);
 	if (len != 0) {
 		wchar_t *text = gb_alloc_array(permanent_allocator(), wchar_t, len+1);
-		GetFullPathNameW(&string16[0], len, text, nullptr);
+		GetFullPathNameW(cast(wchar_t *)&string16[0], len, text, nullptr);
 		mutex_unlock(&fullpath_mutex);
 
 		text[len] = 0;
-		result = string16_to_string(a, make_string16(text, len));
+		result = string16_to_string(a, make_string16(cast(u16 *)text, len));
 		result = string_trim_whitespace(result);
 
 		// Replace Windows style separators
diff --git a/src/cached.cpp b/src/cached.cpp
index efdadce7b..61b5d01b4 100644
--- a/src/cached.cpp
+++ b/src/cached.cpp
@@ -231,7 +231,7 @@ Array<String> cache_gather_envs() {
 
 		wchar_t *curr_string = strings;
 		while (curr_string && *curr_string) {
-			String16 wstr = make_string16_c(curr_string);
+			String16 wstr = make_string16_c(cast(u16 *)curr_string);
 			curr_string += wstr.len+1;
 			String str = string16_to_string(temporary_allocator(), wstr);
 			if (string_starts_with(str, str_lit("CURR_DATE_TIME="))) {
diff --git a/src/check_builtin.cpp b/src/check_builtin.cpp
index 974224ed2..d36cf4520 100644
--- a/src/check_builtin.cpp
+++ b/src/check_builtin.cpp
@@ -2327,6 +2327,9 @@ gb_internal bool check_builtin_procedure(CheckerContext *c, Operand *operand, As
 		if (is_type_string(op_type) && id == BuiltinProc_len) {
 			if (operand->mode == Addressing_Constant) {
 				mode = Addressing_Constant;
+
+				GB_ASSERT_MSG(!is_type_string16(op_type), "TODO(bill): constant utf-16 string len");
+
 				String str = operand->value.value_string;
 				value = exact_value_i64(str.len);
 				type = t_untyped_integer;
@@ -2334,6 +2337,8 @@ gb_internal bool check_builtin_procedure(CheckerContext *c, Operand *operand, As
 				mode = Addressing_Value;
 				if (is_type_cstring(op_type)) {
 					add_package_dependency(c, "runtime", "cstring_len");
+				} else if (is_type_cstring16(op_type)) {
+					add_package_dependency(c, "runtime", "cstring16_len");
 				}
 			}
 		} else if (is_type_array(op_type)) {
@@ -4683,7 +4688,9 @@ gb_internal bool check_builtin_procedure(CheckerContext *c, Operand *operand, As
 				break;
 			case Type_Basic:
 				if (t->Basic.kind == Basic_string) {
-					operand->type = alloc_type_multi_pointer(t_u8);
+					operand->type = t_u8_multi_ptr;
+				} else if (t->Basic.kind == Basic_string16) {
+					operand->type = t_u16_multi_ptr;
 				}
 				break;
 			case Type_Pointer:
diff --git a/src/check_decl.cpp b/src/check_decl.cpp
index dd4c09e85..af46ee40e 100644
--- a/src/check_decl.cpp
+++ b/src/check_decl.cpp
@@ -815,6 +815,12 @@ gb_internal bool signature_parameter_similar_enough(Type *x, Type *y) {
 	if (sig_compare(is_type_cstring, is_type_u8_multi_ptr, x, y)) {
 		return true;
 	}
+	if (sig_compare(is_type_cstring16, is_type_u16_ptr, x, y)) {
+		return true;
+	}
+	if (sig_compare(is_type_cstring16, is_type_u16_multi_ptr, x, y)) {
+		return true;
+	}
 
 	if (sig_compare(is_type_uintptr, is_type_rawptr, x, y)) {
 		return true;
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index 6723a7580..57073e22f 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -2862,6 +2862,14 @@ gb_internal void add_comparison_procedures_for_fields(CheckerContext *c, Type *t
 			add_package_dependency(c, "runtime", "string_eq");
 			add_package_dependency(c, "runtime", "string_ne");
 			break;
+		case Basic_cstring16:
+			add_package_dependency(c, "runtime", "cstring16_eq");
+			add_package_dependency(c, "runtime", "cstring16_ne");
+			break;
+		case Basic_string16:
+			add_package_dependency(c, "runtime", "string16_eq");
+			add_package_dependency(c, "runtime", "string16_ne");
+			break;
 		}
 		break;
 	case Type_Struct:
@@ -3035,6 +3043,24 @@ gb_internal void check_comparison(CheckerContext *c, Ast *node, Operand *x, Oper
 				case Token_LtEq:  add_package_dependency(c, "runtime", "cstring_le"); break;
 				case Token_GtEq:  add_package_dependency(c, "runtime", "cstring_gt"); break;
 				}
+			} else if (is_type_cstring16(x->type) && is_type_cstring16(y->type)) {
+				switch (op) {
+				case Token_CmpEq: add_package_dependency(c, "runtime", "cstring16_eq"); break;
+				case Token_NotEq: add_package_dependency(c, "runtime", "cstring16_ne"); break;
+				case Token_Lt:    add_package_dependency(c, "runtime", "cstring16_lt"); break;
+				case Token_Gt:    add_package_dependency(c, "runtime", "cstring16_gt"); break;
+				case Token_LtEq:  add_package_dependency(c, "runtime", "cstring16_le"); break;
+				case Token_GtEq:  add_package_dependency(c, "runtime", "cstring16_gt"); break;
+				}
+			} else if (is_type_string16(x->type) || is_type_string16(y->type)) {
+				switch (op) {
+				case Token_CmpEq: add_package_dependency(c, "runtime", "string16_eq"); break;
+				case Token_NotEq: add_package_dependency(c, "runtime", "string16_ne"); break;
+				case Token_Lt:    add_package_dependency(c, "runtime", "string16_lt"); break;
+				case Token_Gt:    add_package_dependency(c, "runtime", "string16_gt"); break;
+				case Token_LtEq:  add_package_dependency(c, "runtime", "string16_le"); break;
+				case Token_GtEq:  add_package_dependency(c, "runtime", "string16_gt"); break;
+				}
 			} else if (is_type_string(x->type) || is_type_string(y->type)) {
 				switch (op) {
 				case Token_CmpEq: add_package_dependency(c, "runtime", "string_eq"); break;
@@ -3340,6 +3366,11 @@ gb_internal bool check_is_castable_to(CheckerContext *c, Operand *operand, Type
 		return true;
 	}
 
+	// []u16 <-> string16 (not cstring16)
+	if (is_type_u16_slice(src) && (is_type_string16(dst) && !is_type_cstring16(dst))) {
+		return true;
+	}
+
 	// cstring -> string
 	if (are_types_identical(src, t_cstring) && are_types_identical(dst, t_string)) {
 		if (operand->mode != Addressing_Constant) {
@@ -3347,6 +3378,14 @@ gb_internal bool check_is_castable_to(CheckerContext *c, Operand *operand, Type
 		}
 		return true;
 	}
+	// cstring16 -> string16
+	if (are_types_identical(src, t_cstring16) && are_types_identical(dst, t_string16)) {
+		if (operand->mode != Addressing_Constant) {
+			add_package_dependency(c, "runtime", "cstring16_to_string16");
+		}
+		return true;
+	}
+
 	// cstring -> ^u8
 	if (are_types_identical(src, t_cstring) && is_type_u8_ptr(dst)) {
 		return !is_constant;
@@ -3372,6 +3411,34 @@ gb_internal bool check_is_castable_to(CheckerContext *c, Operand *operand, Type
 	if (is_type_rawptr(src) && are_types_identical(dst, t_cstring)) {
 		return !is_constant;
 	}
+
+	// cstring -> ^u16
+	if (are_types_identical(src, t_cstring16) && is_type_u16_ptr(dst)) {
+		return !is_constant;
+	}
+	// cstring -> [^]u16
+	if (are_types_identical(src, t_cstring16) && is_type_u16_multi_ptr(dst)) {
+		return !is_constant;
+	}
+	// cstring -> rawptr
+	if (are_types_identical(src, t_cstring16) && is_type_rawptr(dst)) {
+		return !is_constant;
+	}
+
+
+	// ^u16 -> cstring16
+	if (is_type_u16_ptr(src) && are_types_identical(dst, t_cstring16)) {
+		return !is_constant;
+	}
+	// [^]u16 -> cstring
+	if (is_type_u16_multi_ptr(src) && are_types_identical(dst, t_cstring16)) {
+		return !is_constant;
+	}
+	// rawptr -> cstring16
+	if (is_type_rawptr(src) && are_types_identical(dst, t_cstring16)) {
+		return !is_constant;
+	}
+
 	// proc <-> proc
 	if (is_type_proc(src) && is_type_proc(dst)) {
 		if (is_type_polymorphic(dst)) {
@@ -4558,6 +4625,8 @@ gb_internal void convert_to_typed(CheckerContext *c, Operand *operand, Type *tar
 					// target_type = t_untyped_nil;
 				} else if (is_type_cstring(target_type)) {
 					// target_type = t_untyped_nil;
+				} else if (is_type_cstring16(target_type)) {
+					// target_type = t_untyped_nil;
 				} else if (!type_has_nil(target_type)) {
 					operand->mode = Addressing_Invalid;
 					convert_untyped_error(c, operand, target_type);
@@ -8226,6 +8295,7 @@ gb_internal bool check_set_index_data(Operand *o, Type *t, bool indirection, i64
 	case Type_Basic:
 		if (t->Basic.kind == Basic_string) {
 			if (o->mode == Addressing_Constant) {
+				GB_ASSERT(o->value.kind == ExactValue_String);
 				*max_count = o->value.value_string.len;
 			}
 			if (o->mode != Addressing_Constant) {
@@ -8233,6 +8303,16 @@ gb_internal bool check_set_index_data(Operand *o, Type *t, bool indirection, i64
 			}
 			o->type = t_u8;
 			return true;
+		} else if (t->Basic.kind == Basic_string16) {
+			if (o->mode == Addressing_Constant) {
+				GB_ASSERT(o->value.kind == ExactValue_String16);
+				*max_count = o->value.value_string16.len;
+			}
+			if (o->mode != Addressing_Constant) {
+				o->mode = Addressing_Value;
+			}
+			o->type = t_u16;
+			return true;
 		} else if (t->Basic.kind == Basic_UntypedString) {
 			if (o->mode == Addressing_Constant) {
 				*max_count = o->value.value_string.len;
@@ -10879,9 +10959,17 @@ gb_internal ExprKind check_slice_expr(CheckerContext *c, Operand *o, Ast *node,
 		if (t->Basic.kind == Basic_string || t->Basic.kind == Basic_UntypedString) {
 			valid = true;
 			if (o->mode == Addressing_Constant) {
+				GB_ASSERT(o->value.kind == ExactValue_String);
 				max_count = o->value.value_string.len;
 			}
 			o->type = type_deref(o->type);
+		} else if (t->Basic.kind == Basic_string16) {
+			valid = true;
+			if (o->mode == Addressing_Constant) {
+				GB_ASSERT(o->value.kind == ExactValue_String16);
+				max_count = o->value.value_string16.len;
+			}
+			o->type = type_deref(o->type);
 		}
 		break;
 
diff --git a/src/checker.cpp b/src/checker.cpp
index a1d8f98d7..20da5b19b 100644
--- a/src/checker.cpp
+++ b/src/checker.cpp
@@ -1363,13 +1363,15 @@ gb_internal void init_universal(void) {
 	}
 
 
-	t_u8_ptr       = alloc_type_pointer(t_u8);
-	t_u8_multi_ptr = alloc_type_multi_pointer(t_u8);
-	t_int_ptr      = alloc_type_pointer(t_int);
-	t_i64_ptr      = alloc_type_pointer(t_i64);
-	t_f64_ptr      = alloc_type_pointer(t_f64);
-	t_u8_slice     = alloc_type_slice(t_u8);
-	t_string_slice = alloc_type_slice(t_string);
+	t_u8_ptr        = alloc_type_pointer(t_u8);
+	t_u8_multi_ptr  = alloc_type_multi_pointer(t_u8);
+	t_u16_ptr       = alloc_type_pointer(t_u16);
+	t_u16_multi_ptr = alloc_type_multi_pointer(t_u16);
+	t_int_ptr       = alloc_type_pointer(t_int);
+	t_i64_ptr       = alloc_type_pointer(t_i64);
+	t_f64_ptr       = alloc_type_pointer(t_f64);
+	t_u8_slice      = alloc_type_slice(t_u8);
+	t_string_slice  = alloc_type_slice(t_string);
 
 	// intrinsics types for objective-c stuff
 	{
diff --git a/src/common.cpp b/src/common.cpp
index ad1e5a851..b3761fc36 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -669,7 +669,7 @@ gb_internal gb_inline f64 gb_sqrt(f64 x) {
 gb_internal wchar_t **command_line_to_wargv(wchar_t *cmd_line, int *_argc) {
 	u32 i, j;
 
-	u32 len = cast(u32)string16_len(cmd_line);
+	u32 len = cast(u32)string16_len(cast(u16 *)cmd_line);
 	i = ((len+2)/2)*gb_size_of(void *) + gb_size_of(void *);
 
 	wchar_t **argv = cast(wchar_t **)GlobalAlloc(GMEM_FIXED, i + (len+2)*gb_size_of(wchar_t));
diff --git a/src/exact_value.cpp b/src/exact_value.cpp
index 37751c8f1..f2aed84c2 100644
--- a/src/exact_value.cpp
+++ b/src/exact_value.cpp
@@ -29,6 +29,7 @@ enum ExactValueKind {
 	ExactValue_Compound   = 8,
 	ExactValue_Procedure  = 9,
 	ExactValue_Typeid     = 10,
+	ExactValue_String16   = 11,
 
 	ExactValue_Count,
 };
@@ -46,6 +47,7 @@ struct ExactValue {
 		Ast *          value_compound;
 		Ast *          value_procedure;
 		Type *         value_typeid;
+		String16       value_string16;
 	};
 };
 
@@ -66,6 +68,9 @@ gb_internal uintptr hash_exact_value(ExactValue v) {
 	case ExactValue_String:
 		res = gb_fnv32a(v.value_string.text, v.value_string.len);
 		break;
+	case ExactValue_String16:
+		res = gb_fnv32a(v.value_string.text, v.value_string.len*gb_size_of(u16));
+		break;
 	case ExactValue_Integer:
 		{
 			u32 key = gb_fnv32a(v.value_integer.dp, gb_size_of(*v.value_integer.dp) * v.value_integer.used);
@@ -118,6 +123,11 @@ gb_internal ExactValue exact_value_string(String string) {
 	result.value_string = string;
 	return result;
 }
+gb_internal ExactValue exact_value_string16(String16 string) {
+	ExactValue result = {ExactValue_String16};
+	result.value_string16 = string;
+	return result;
+}
 
 gb_internal ExactValue exact_value_i64(i64 i) {
 	ExactValue result = {ExactValue_Integer};
@@ -656,6 +666,7 @@ gb_internal i32 exact_value_order(ExactValue const &v) {
 		return 0;
 	case ExactValue_Bool:
 	case ExactValue_String:
+	case ExactValue_String16:
 		return 1;
 	case ExactValue_Integer:
 		return 2;
@@ -689,6 +700,7 @@ gb_internal void match_exact_values(ExactValue *x, ExactValue *y) {
 
 	case ExactValue_Bool:
 	case ExactValue_String:
+	case ExactValue_String16:
 	case ExactValue_Quaternion:
 	case ExactValue_Pointer:
 	case ExactValue_Compound:
@@ -891,7 +903,18 @@ gb_internal ExactValue exact_binary_operator_value(TokenKind op, ExactValue x, E
 		gb_memmove(data,        sx.text, sx.len);
 		gb_memmove(data+sx.len, sy.text, sy.len);
 		return exact_value_string(make_string(data, len));
-		break;
+	}
+	case ExactValue_String16: {
+		if (op != Token_Add) goto error;
+
+		// NOTE(bill): How do you minimize this over allocation?
+		String sx = x.value_string;
+		String sy = y.value_string;
+		isize len = sx.len+sy.len;
+		u16 *data = gb_alloc_array(permanent_allocator(), u16, len);
+		gb_memmove(data,        sx.text, sx.len*gb_size_of(u16));
+		gb_memmove(data+sx.len, sy.text, sy.len*gb_size_of(u16));
+		return exact_value_string16(make_string16(data, len));
 	}
 	}
 
@@ -994,6 +1017,19 @@ gb_internal bool compare_exact_values(TokenKind op, ExactValue x, ExactValue y)
 		}
 		break;
 	}
+	case ExactValue_String16: {
+		String16 a = x.value_string16;
+		String16 b = y.value_string16;
+		switch (op) {
+		case Token_CmpEq: return a == b;
+		case Token_NotEq: return a != b;
+		case Token_Lt:    return a <  b;
+		case Token_LtEq:  return a <= b;
+		case Token_Gt:    return a >  b;
+		case Token_GtEq:  return a >= b;
+		}
+		break;
+	}
 
 	case ExactValue_Pointer: {
 		switch (op) {
@@ -1050,6 +1086,20 @@ gb_internal gbString write_exact_value_to_string(gbString str, ExactValue const
 		gb_free(heap_allocator(), s.text);
 		return str;
 	}
+	case ExactValue_String16: {
+		String s = quote_to_ascii(heap_allocator(), v.value_string16);
+		string_limit = gb_max(string_limit, 36);
+		if (s.len <= string_limit) {
+			str = gb_string_append_length(str, s.text, s.len);
+		} else {
+			isize n = string_limit/5;
+			str = gb_string_append_length(str, s.text, n);
+			str = gb_string_append_fmt(str, "\"..%lld chars..\"", s.len-(2*n));
+			str = gb_string_append_length(str, s.text+s.len-n, n);
+		}
+		gb_free(heap_allocator(), s.text);
+		return str;
+	}
 	case ExactValue_Integer: {
 		String s = big_int_to_string(heap_allocator(), &v.value_integer);
 		str = gb_string_append_length(str, s.text, s.len);
diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index 74aea82f1..fbf0dea11 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -1656,6 +1656,8 @@ gb_internal lbValue lb_emit_conv(lbProcedure *p, lbValue value, Type *t) {
 				res.type = t;
 				res.value = llvm_cstring(m, str);
 				return res;
+			} else if (src->kind == Type_Basic && src->Basic.kind == Basic_string16 && dst->Basic.kind == Basic_cstring16) {
+				GB_PANIC("TODO(bill): UTF-16 string");
 			}
 			// if (is_type_float(dst)) {
 			// 	return value;
@@ -1795,6 +1797,38 @@ gb_internal lbValue lb_emit_conv(lbProcedure *p, lbValue value, Type *t) {
 	}
 
 
+
+	if (is_type_cstring16(src) && is_type_u16_ptr(dst)) {
+		return lb_emit_transmute(p, value, dst);
+	}
+	if (is_type_u16_ptr(src) && is_type_cstring16(dst)) {
+		return lb_emit_transmute(p, value, dst);
+	}
+	if (is_type_cstring16(src) && is_type_u16_multi_ptr(dst)) {
+		return lb_emit_transmute(p, value, dst);
+	}
+	if (is_type_u8_multi_ptr(src) && is_type_cstring16(dst)) {
+		return lb_emit_transmute(p, value, dst);
+	}
+	if (is_type_cstring16(src) && is_type_rawptr(dst)) {
+		return lb_emit_transmute(p, value, dst);
+	}
+	if (is_type_rawptr(src) && is_type_cstring16(dst)) {
+		return lb_emit_transmute(p, value, dst);
+	}
+
+	if (are_types_identical(src, t_cstring16) && are_types_identical(dst, t_string16)) {
+		TEMPORARY_ALLOCATOR_GUARD();
+
+		lbValue c = lb_emit_conv(p, value, t_cstring16);
+		auto args = array_make<lbValue>(temporary_allocator(), 1);
+		args[0] = c;
+		lbValue s = lb_emit_runtime_call(p, "cstring16_to_string16", args);
+		return lb_emit_conv(p, s, dst);
+	}
+
+
+
 	// integer -> boolean
 	if (is_type_integer(src) && is_type_boolean(dst)) {
 		lbValue res = {};
@@ -2296,6 +2330,14 @@ gb_internal lbValue lb_emit_conv(lbProcedure *p, lbValue value, Type *t) {
 		return res;
 	}
 
+	// []u16 <-> string16
+	if (is_type_u16_slice(src) && is_type_string16(dst)) {
+		return lb_emit_transmute(p, value, t);
+	}
+	if (is_type_string16(src) && is_type_u16_slice(dst)) {
+		return lb_emit_transmute(p, value, t);
+	}
+
 	// []byte/[]u8 <-> string
 	if (is_type_u8_slice(src) && is_type_string(dst)) {
 		return lb_emit_transmute(p, value, t);
@@ -2304,6 +2346,7 @@ gb_internal lbValue lb_emit_conv(lbProcedure *p, lbValue value, Type *t) {
 		return lb_emit_transmute(p, value, t);
 	}
 
+
 	if (is_type_array_like(dst)) {
 		Type *elem = base_array_type(dst);
 		isize index_count = cast(isize)get_array_type_count(dst);
@@ -2483,6 +2526,12 @@ gb_internal lbValue lb_emit_conv(lbProcedure *p, lbValue value, Type *t) {
 
 
 	if (is_type_untyped(src)) {
+		if (is_type_string(src) && is_type_string16(dst)) {
+			GB_PANIC("TODO(bill): UTF-16 string");
+			lbAddr result = lb_add_local_generated(p, t, false);
+			lb_addr_store(p, result, value);
+			return lb_addr_load(p, result);
+		}
 		if (is_type_string(src) && is_type_string(dst)) {
 			lbAddr result = lb_add_local_generated(p, t, false);
 			lb_addr_store(p, result, value);
@@ -3056,6 +3105,13 @@ gb_internal lbValue lb_emit_comp_against_nil(lbProcedure *p, TokenKind op_kind,
 				res.value = LLVMBuildIsNotNull(p->builder, x.value, "");
 			}
 			return res;
+		case Basic_cstring16:
+			if (op_kind == Token_CmpEq) {
+				res.value = LLVMBuildIsNull(p->builder, x.value, "");
+			} else if (op_kind == Token_NotEq) {
+				res.value = LLVMBuildIsNotNull(p->builder, x.value, "");
+			}
+			return res;
 		case Basic_any:
 			{
 				// TODO(bill): is this correct behaviour for nil comparison for any?
@@ -4432,6 +4488,22 @@ gb_internal lbAddr lb_build_addr_slice_expr(lbProcedure *p, Ast *expr) {
 	}
 
 	case Type_Basic: {
+		if (is_type_string16(type)) {
+			GB_ASSERT_MSG(are_types_identical(type, t_string16), "got %s", type_to_string(type));
+			lbValue len = lb_string_len(p, base);
+			if (high.value == nullptr) high = len;
+
+			if (!no_indices) {
+				lb_emit_slice_bounds_check(p, se->open, low, high, len, se->low != nullptr);
+			}
+
+			lbValue elem    = lb_emit_ptr_offset(p, lb_string_elem(p, base), low);
+			lbValue new_len = lb_emit_arith(p, Token_Sub, high, low, t_int);
+
+			lbAddr str = lb_add_local_generated(p, t_string16, false);
+			lb_fill_string(p, str, elem, new_len);
+			return str;
+		}
 		GB_ASSERT_MSG(are_types_identical(type, t_string), "got %s", type_to_string(type));
 		lbValue len = lb_string_len(p, base);
 		if (high.value == nullptr) high = len;
diff --git a/src/llvm_backend_general.cpp b/src/llvm_backend_general.cpp
index 3ce0c725f..d9771a75b 100644
--- a/src/llvm_backend_general.cpp
+++ b/src/llvm_backend_general.cpp
@@ -1812,6 +1812,37 @@ gb_internal LLVMTypeRef lb_type_internal(lbModule *m, Type *type) {
 				return type;
 			}
 		case Basic_cstring: return LLVMPointerType(LLVMInt8TypeInContext(ctx), 0);
+
+
+		case Basic_string16:
+			{
+				char const *name = "..string16";
+				LLVMTypeRef type = LLVMGetTypeByName(m->mod, name);
+				if (type != nullptr) {
+					return type;
+				}
+				type = LLVMStructCreateNamed(ctx, name);
+
+				if (build_context.metrics.ptr_size < build_context.metrics.int_size) {
+					GB_ASSERT(build_context.metrics.ptr_size == 4);
+					GB_ASSERT(build_context.metrics.int_size == 8);
+					LLVMTypeRef fields[3] = {
+						LLVMPointerType(lb_type(m, t_u16), 0),
+						lb_type(m, t_i32),
+						lb_type(m, t_int),
+					};
+					LLVMStructSetBody(type, fields, 3, false);
+				} else {
+					LLVMTypeRef fields[2] = {
+						LLVMPointerType(lb_type(m, t_u16), 0),
+						lb_type(m, t_int),
+					};
+					LLVMStructSetBody(type, fields, 2, false);
+				}
+				return type;
+			}
+		case Basic_cstring16: return LLVMPointerType(LLVMInt16TypeInContext(ctx), 0);
+
 		case Basic_any:
 			{
 				char const *name = "..any";
diff --git a/src/llvm_backend_proc.cpp b/src/llvm_backend_proc.cpp
index e63c92f6f..8f306b771 100644
--- a/src/llvm_backend_proc.cpp
+++ b/src/llvm_backend_proc.cpp
@@ -2289,6 +2289,10 @@ gb_internal lbValue lb_build_builtin_proc(lbProcedure *p, Ast *expr, TypeAndValu
 		}
 		if (is_type_cstring(t)) {
 			return lb_cstring_len(p, v);
+		} else if (is_type_cstring16(t)) {
+			return lb_cstring16_len(p, v);
+		} else if (is_type_string16(t)) {
+			return lb_string_len(p, v);
 		} else if (is_type_string(t)) {
 			return lb_string_len(p, v);
 		} else if (is_type_array(t)) {
@@ -2728,6 +2732,11 @@ gb_internal lbValue lb_build_builtin_proc(lbProcedure *p, Ast *expr, TypeAndValu
 					res = lb_emit_conv(p, res, tv.type);
 				} else if (t->Basic.kind == Basic_cstring) {
 					res = lb_emit_conv(p, x, tv.type);
+				} else if (t->Basic.kind == Basic_string16) {
+					res = lb_string_elem(p, x);
+					res = lb_emit_conv(p, res, tv.type);
+				} else if (t->Basic.kind == Basic_cstring16) {
+					res = lb_emit_conv(p, x, tv.type);
 				}
 				break;
 			case Type_Pointer:
diff --git a/src/llvm_backend_type.cpp b/src/llvm_backend_type.cpp
index 43c5f0b40..a91d77fe5 100644
--- a/src/llvm_backend_type.cpp
+++ b/src/llvm_backend_type.cpp
@@ -531,7 +531,33 @@ gb_internal void lb_setup_type_info_data_giant_array(lbModule *m, i64 global_typ
 			case Basic_cstring:
 				{
 					tag_type = t_type_info_string;
-					LLVMValueRef vals[1] = {
+					LLVMValueRef vals[2] = {
+						lb_const_bool(m, t_bool, true).value,
+						lb_const_bool(m, t_bool, false).value,
+					};
+
+					variant_value = llvm_const_named_struct(m, tag_type, vals, gb_count_of(vals));
+				}
+				break;
+
+			case Basic_string16:
+				{
+					tag_type = t_type_info_string;
+					LLVMValueRef vals[2] = {
+						lb_const_bool(m, t_bool, false).value,
+						lb_const_bool(m, t_bool, true).value,
+					};
+
+					variant_value = llvm_const_named_struct(m, tag_type, vals, gb_count_of(vals));
+				}
+				break;
+
+
+			case Basic_cstring16:
+				{
+					tag_type = t_type_info_string;
+					LLVMValueRef vals[2] = {
+						lb_const_bool(m, t_bool, true).value,
 						lb_const_bool(m, t_bool, true).value,
 					};
 
diff --git a/src/llvm_backend_utility.cpp b/src/llvm_backend_utility.cpp
index 521553147..d4117b7ff 100644
--- a/src/llvm_backend_utility.cpp
+++ b/src/llvm_backend_utility.cpp
@@ -1626,11 +1626,17 @@ gb_internal void lb_fill_string(lbProcedure *p, lbAddr const &string, lbValue ba
 
 gb_internal lbValue lb_string_elem(lbProcedure *p, lbValue string) {
 	Type *t = base_type(string.type);
+	if (t->kind == Type_Basic && t->Basic.kind == Basic_string16) {
+		return lb_emit_struct_ev(p, string, 0);
+	}
 	GB_ASSERT(t->kind == Type_Basic && t->Basic.kind == Basic_string);
 	return lb_emit_struct_ev(p, string, 0);
 }
 gb_internal lbValue lb_string_len(lbProcedure *p, lbValue string) {
 	Type *t = base_type(string.type);
+	if (t->kind == Type_Basic && t->Basic.kind == Basic_string16) {
+		return lb_emit_struct_ev(p, string, 1);
+	}
 	GB_ASSERT_MSG(t->kind == Type_Basic && t->Basic.kind == Basic_string, "%s", type_to_string(t));
 	return lb_emit_struct_ev(p, string, 1);
 }
@@ -1641,6 +1647,12 @@ gb_internal lbValue lb_cstring_len(lbProcedure *p, lbValue value) {
 	args[0] = lb_emit_conv(p, value, t_cstring);
 	return lb_emit_runtime_call(p, "cstring_len", args);
 }
+gb_internal lbValue lb_cstring16_len(lbProcedure *p, lbValue value) {
+	GB_ASSERT(is_type_cstring16(value.type));
+	auto args = array_make<lbValue>(permanent_allocator(), 1);
+	args[0] = lb_emit_conv(p, value, t_cstring16);
+	return lb_emit_runtime_call(p, "cstring16_len", args);
+}
 
 
 gb_internal lbValue lb_array_elem(lbProcedure *p, lbValue array_ptr) {
diff --git a/src/main.cpp b/src/main.cpp
index 112d1208a..5a43e3c02 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -142,9 +142,9 @@ gb_internal i32 system_exec_command_line_app_internal(bool exit_on_err, char con
 	}
 
 	wcmd = string_to_string16(permanent_allocator(), make_string(cast(u8 *)cmd_line, cmd_len-1));
-	if (CreateProcessW(nullptr, wcmd.text,
-					   nullptr, nullptr, true, 0, nullptr, nullptr,
-					   &start_info, &pi)) {
+	if (CreateProcessW(nullptr, cast(wchar_t *)wcmd.text,
+	                   nullptr, nullptr, true, 0, nullptr, nullptr,
+	                   &start_info, &pi)) {
 		WaitForSingleObject(pi.hProcess, INFINITE);
 		GetExitCodeProcess(pi.hProcess, cast(DWORD *)&exit_code);
 
@@ -232,7 +232,7 @@ gb_internal Array<String> setup_args(int argc, char const **argv) {
 	wchar_t **wargv = command_line_to_wargv(GetCommandLineW(), &wargc);
 	auto args = array_make<String>(a, 0, wargc);
 	for (isize i = 0; i < wargc; i++) {
-		wchar_t *warg = wargv[i];
+		u16 *warg = cast(u16 *)wargv[i];
 		isize wlen = string16_len(warg);
 		String16 wstr = make_string16(warg, wlen);
 		String arg = string16_to_string(a, wstr);
diff --git a/src/microsoft_craziness.h b/src/microsoft_craziness.h
index b0fd22a23..933607a2a 100644
--- a/src/microsoft_craziness.h
+++ b/src/microsoft_craziness.h
@@ -59,7 +59,7 @@ struct Find_Result {
 };
 
 gb_internal String mc_wstring_to_string(wchar_t const *str) {
-	return string16_to_string(mc_allocator, make_string16_c(str));
+	return string16_to_string(mc_allocator, make_string16_c(cast(u16 *)str));
 }
 
 gb_internal String16 mc_string_to_wstring(String str) {
@@ -103,7 +103,7 @@ gb_internal HANDLE mc_find_first(String wildcard, MC_Find_Data *find_data) {
  	String16 wildcard_wide = mc_string_to_wstring(wildcard);
  	defer (mc_free(wildcard_wide));
 
- 	HANDLE handle = FindFirstFileW(wildcard_wide.text, &_find_data);
+ 	HANDLE handle = FindFirstFileW(cast(wchar_t *)wildcard_wide.text, &_find_data);
  	if (handle == INVALID_HANDLE_VALUE) return INVALID_HANDLE_VALUE;
 
  	find_data->file_attributes = _find_data.dwFileAttributes;
diff --git a/src/path.cpp b/src/path.cpp
index d5e982088..2b97a04df 100644
--- a/src/path.cpp
+++ b/src/path.cpp
@@ -130,7 +130,7 @@ gb_internal String directory_from_path(String const &s) {
 		String16 wstr = string_to_string16(a, path);
 		defer (gb_free(a, wstr.text));
 
-		i32 attribs = GetFileAttributesW(wstr.text);
+		i32 attribs = GetFileAttributesW(cast(wchar_t *)wstr.text);
 		if (attribs < 0) return false;
 
 		return (attribs & FILE_ATTRIBUTE_DIRECTORY) != 0;
@@ -360,7 +360,7 @@ gb_internal ReadDirectoryError read_directory(String path, Array<FileInfo> *fi)
 	defer (gb_free(a, wstr.text));
 
 	WIN32_FIND_DATAW file_data = {};
-	HANDLE find_file = FindFirstFileW(wstr.text, &file_data);
+	HANDLE find_file = FindFirstFileW(cast(wchar_t *)wstr.text, &file_data);
 	if (find_file == INVALID_HANDLE_VALUE) {
 		return ReadDirectory_Unknown;
 	}
@@ -372,7 +372,7 @@ gb_internal ReadDirectoryError read_directory(String path, Array<FileInfo> *fi)
 		wchar_t *filename_w = file_data.cFileName;
 		u64 size = cast(u64)file_data.nFileSizeLow;
 		size |= (cast(u64)file_data.nFileSizeHigh) << 32;
-		String name = string16_to_string(a, make_string16_c(filename_w));
+		String name = string16_to_string(a, make_string16_c(cast(u16 *)filename_w));
 		if (name == "." || name == "..") {
 			gb_free(a, name.text);
 			continue;
@@ -494,7 +494,7 @@ gb_internal bool write_directory(String path) {
 #else
 gb_internal bool write_directory(String path) {
 	String16 wstr = string_to_string16(heap_allocator(), path);
-	LPCWSTR wdirectory_name = wstr.text;
+	LPCWSTR wdirectory_name = cast(wchar_t *)wstr.text;
 
 	HANDLE directory = CreateFileW(wdirectory_name,
 			GENERIC_WRITE,
diff --git a/src/string.cpp b/src/string.cpp
index ae8d066b1..8405938f4 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -26,15 +26,14 @@ struct String_Iterator {
 
 // NOTE(bill): String16 is only used for Windows due to its file directories
 struct String16 {
-	wchar_t *text;
-	isize    len;
-	wchar_t const &operator[](isize i) const {
+	u16 * text;
+	isize len;
+	u16 const &operator[](isize i) const {
 		GB_ASSERT_MSG(0 <= i && i < len, "[%td]", i);
 		return text[i];
 	}
 };
 
-
 gb_internal gb_inline String make_string(u8 const *text, isize len) {
 	String s;
 	s.text = cast(u8 *)text;
@@ -45,19 +44,19 @@ gb_internal gb_inline String make_string(u8 const *text, isize len) {
 	return s;
 }
 
-
-gb_internal gb_inline String16 make_string16(wchar_t const *text, isize len) {
+gb_internal gb_inline String16 make_string16(u16 const *text, isize len) {
 	String16 s;
-	s.text = cast(wchar_t *)text;
+	s.text = cast(u16 *)text;
 	s.len = len;
 	return s;
 }
 
-gb_internal isize string16_len(wchar_t const *s) {
+
+gb_internal isize string16_len(u16 const *s) {
 	if (s == nullptr) {
 		return 0;
 	}
-	wchar_t const *p = s;
+	u16 const *p = s;
 	while (*p) {
 		p++;
 	}
@@ -69,7 +68,7 @@ gb_internal gb_inline String make_string_c(char const *text) {
 	return make_string(cast(u8 *)cast(void *)text, gb_strlen(text));
 }
 
-gb_internal gb_inline String16 make_string16_c(wchar_t const *text) {
+gb_internal gb_inline String16 make_string16_c(u16 const *text) {
 	return make_string16(text, string16_len(text));
 }
 
@@ -145,6 +144,27 @@ gb_internal int string_compare(String const &a, String const &b) {
 	return res;
 }
 
+
+gb_internal int string16_compare(String16 const &a, String16 const &b) {
+	if (a.text == b.text) {
+		return cast(int)(a.len - b.len);
+	}
+	if (a.text == nullptr) {
+		return -1;
+	}
+	if (b.text == nullptr) {
+		return +1;
+	}
+
+	uintptr n = gb_min(a.len, b.len);
+	int res = memcmp(a.text, b.text, n*gb_size_of(u16));
+	if (res == 0) {
+		res = cast(int)(a.len - b.len);
+	}
+	return res;
+}
+
+
 gb_internal isize string_index_byte(String const &s, u8 x) {
 	for (isize i = 0; i < s.len; i++) {
 		if (s.text[i] == x) {
@@ -182,6 +202,26 @@ template <isize N> gb_internal bool operator >= (String const &a, char const (&b
 template <> bool operator == (String const &a, char const (&b)[1]) { return a.len == 0; }
 template <> bool operator != (String const &a, char const (&b)[1]) { return a.len != 0; }
 
+
+gb_internal gb_inline bool str_eq(String16 const &a, String16 const &b) {
+	if (a.len != b.len) return false;
+	if (a.len == 0) return true;
+	return memcmp(a.text, b.text, a.len) == 0;
+}
+gb_internal gb_inline bool str_ne(String16 const &a, String16 const &b) { return !str_eq(a, b);                }
+gb_internal gb_inline bool str_lt(String16 const &a, String16 const &b) { return string16_compare(a, b) < 0;     }
+gb_internal gb_inline bool str_gt(String16 const &a, String16 const &b) { return string16_compare(a, b) > 0;     }
+gb_internal gb_inline bool str_le(String16 const &a, String16 const &b) { return string16_compare(a, b) <= 0;    }
+gb_internal gb_inline bool str_ge(String16 const &a, String16 const &b) { return string16_compare(a, b) >= 0;    }
+
+gb_internal gb_inline bool operator == (String16 const &a, String16 const &b) { return str_eq(a, b); }
+gb_internal gb_inline bool operator != (String16 const &a, String16 const &b) { return str_ne(a, b); }
+gb_internal gb_inline bool operator <  (String16 const &a, String16 const &b) { return str_lt(a, b); }
+gb_internal gb_inline bool operator >  (String16 const &a, String16 const &b) { return str_gt(a, b); }
+gb_internal gb_inline bool operator <= (String16 const &a, String16 const &b) { return str_le(a, b); }
+gb_internal gb_inline bool operator >= (String16 const &a, String16 const &b) { return str_ge(a, b); }
+
+
 gb_internal gb_inline bool string_starts_with(String const &s, String const &prefix) {
 	if (prefix.len > s.len) {
 		return false;
@@ -614,7 +654,7 @@ gb_internal String normalize_path(gbAllocator a, String const &path, String cons
 // TODO(bill): Make this non-windows specific
 gb_internal String16 string_to_string16(gbAllocator a, String s) {
 	int len, len1;
-	wchar_t *text;
+	u16 *text;
 
 	if (s.len < 1) {
 		return make_string16(nullptr, 0);
@@ -625,9 +665,9 @@ gb_internal String16 string_to_string16(gbAllocator a, String s) {
 		return make_string16(nullptr, 0);
 	}
 
-	text = gb_alloc_array(a, wchar_t, len+1);
+	text = gb_alloc_array(a, u16, len+1);
 
-	len1 = convert_multibyte_to_widechar(cast(char *)s.text, cast(int)s.len, text, cast(int)len);
+	len1 = convert_multibyte_to_widechar(cast(char *)s.text, cast(int)s.len, cast(wchar_t *)text, cast(int)len);
 	if (len1 == 0) {
 		gb_free(a, text);
 		return make_string16(nullptr, 0);
@@ -646,7 +686,7 @@ gb_internal String string16_to_string(gbAllocator a, String16 s) {
 		return make_string(nullptr, 0);
 	}
 
-	len = convert_widechar_to_multibyte(s.text, cast(int)s.len, nullptr, 0);
+	len = convert_widechar_to_multibyte(cast(wchar_t *)s.text, cast(int)s.len, nullptr, 0);
 	if (len == 0) {
 		return make_string(nullptr, 0);
 	}
@@ -654,7 +694,7 @@ gb_internal String string16_to_string(gbAllocator a, String16 s) {
 
 	text = gb_alloc_array(a, u8, len+1);
 
-	len1 = convert_widechar_to_multibyte(s.text, cast(int)s.len, cast(char *)text, cast(int)len);
+	len1 = convert_widechar_to_multibyte(cast(wchar_t *)s.text, cast(int)s.len, cast(char *)text, cast(int)len);
 	if (len1 == 0) {
 		gb_free(a, text);
 		return make_string(nullptr, 0);
@@ -674,9 +714,9 @@ gb_internal String temporary_directory(gbAllocator allocator) {
 		return String{0};
 	}
 	DWORD len = gb_max(MAX_PATH, n);
-	wchar_t *b = gb_alloc_array(heap_allocator(), wchar_t, len+1);
+	u16 *b = gb_alloc_array(heap_allocator(), u16, len+1);
 	defer (gb_free(heap_allocator(), b));
-	n = GetTempPathW(len, b);
+	n = GetTempPathW(len, cast(wchar_t *)b);
 	if (n == 3 && b[1] == ':' && b[2] == '\\') {
 
 	} else if (n > 0 && b[n-1] == '\\') {
@@ -791,6 +831,104 @@ gb_internal String quote_to_ascii(gbAllocator a, String str, u8 quote='"') {
 	return res;
 }
 
+gb_internal Rune decode_surrogate_pair(u16 r1, u16 r2) {
+	static Rune const _surr1     = 0xd800;
+	static Rune const _surr2     = 0xdc00;
+	static Rune const _surr3     = 0xe000;
+	static Rune const _surr_self = 0x10000;
+
+	if (_surr1 <= r1 && r1 < _surr2 && _surr2 <= r2 && r2 < _surr3) {
+		return (((r1-_surr1)<<10) | (r2 - _surr2)) + _surr_self;
+	}
+	return GB_RUNE_INVALID;
+}
+
+gb_internal String quote_to_ascii(gbAllocator a, String16 str, u8 quote='"') {
+	static Rune const _surr1     = 0xd800;
+	static Rune const _surr2     = 0xdc00;
+	static Rune const _surr3     = 0xe000;
+	static Rune const _surr_self = 0x10000;
+
+	u16 *s = cast(u16 *)str.text;
+	isize n = str.len;
+	auto buf = array_make<u8>(a, 0, n*2);
+	array_add(&buf, quote);
+	for (isize width = 0; n > 0; s += width, n -= width) {
+		Rune r = cast(Rune)s[0];
+		width = 1;
+		if (r < _surr1 || _surr3 <= r) {
+			r = cast(Rune)r;
+		} else if (_surr1 <= r && r < _surr2) {
+			if (n>1) {
+				r = decode_surrogate_pair(s[0], s[1]);
+				if (r != GB_RUNE_INVALID) {
+					width = 2;
+				}
+			} else {
+				r = GB_RUNE_INVALID;
+			}
+		}
+		if (width == 1 && r == GB_RUNE_INVALID) {
+			array_add(&buf, cast(u8)'\\');
+			array_add(&buf, cast(u8)'x');
+			array_add(&buf, cast(u8)lower_hex[s[0]>>4]);
+			array_add(&buf, cast(u8)lower_hex[s[0]&0xf]);
+			continue;
+		}
+
+		if (r == quote || r == '\\') {
+			array_add(&buf, cast(u8)'\\');
+			array_add(&buf, u8(r));
+			continue;
+		}
+		if (r < 0x80 && is_printable(r)) {
+			array_add(&buf, u8(r));
+			continue;
+		}
+		switch (r) {
+		case '\a':
+		case '\b':
+		case '\f':
+		case '\n':
+		case '\r':
+		case '\t':
+		case '\v':
+		default:
+			if (r < ' ') {
+				u8 b = cast(u8)r;
+				array_add(&buf, cast(u8)'\\');
+				array_add(&buf, cast(u8)'x');
+				array_add(&buf, cast(u8)lower_hex[b>>4]);
+				array_add(&buf, cast(u8)lower_hex[b&0xf]);
+			}
+			if (r > GB_RUNE_MAX) {
+				r = 0XFFFD;
+			}
+			if (r < 0x10000) {
+				array_add(&buf, cast(u8)'\\');
+				array_add(&buf, cast(u8)'u');
+				for (isize i = 12; i >= 0; i -= 4) {
+					array_add(&buf, cast(u8)lower_hex[(r>>i)&0xf]);
+				}
+			} else {
+				array_add(&buf, cast(u8)'\\');
+				array_add(&buf, cast(u8)'U');
+				for (isize i = 28; i >= 0; i -= 4) {
+					array_add(&buf, cast(u8)lower_hex[(r>>i)&0xf]);
+				}
+			}
+		}
+	}
+
+
+
+	array_add(&buf, quote);
+	String res = {};
+	res.text = buf.data;
+	res.len = buf.count;
+	return res;
+}
+
 
 
 
diff --git a/src/types.cpp b/src/types.cpp
index 2e696810d..ad576c8af 100644
--- a/src/types.cpp
+++ b/src/types.cpp
@@ -41,8 +41,13 @@ enum BasicKind {
 	Basic_uint,
 	Basic_uintptr,
 	Basic_rawptr,
-	Basic_string,  // ^u8 + int
-	Basic_cstring, // ^u8
+
+	Basic_string,  // [^]u8 + int
+	Basic_cstring, // [^]u8
+
+	Basic_string16,  // [^]u16 + int
+	Basic_cstring16, // [^]u16 + int
+
 	Basic_any,     // rawptr + ^Type_Info
 
 	Basic_typeid,
@@ -500,8 +505,14 @@ gb_global Type basic_types[] = {
 	{Type_Basic, {Basic_uintptr,           BasicFlag_Integer | BasicFlag_Unsigned,    -1, STR_LIT("uintptr")}},
 
 	{Type_Basic, {Basic_rawptr,            BasicFlag_Pointer,                         -1, STR_LIT("rawptr")}},
+
 	{Type_Basic, {Basic_string,            BasicFlag_String,                          -1, STR_LIT("string")}},
 	{Type_Basic, {Basic_cstring,           BasicFlag_String,                          -1, STR_LIT("cstring")}},
+
+	{Type_Basic, {Basic_string16,          BasicFlag_String,                          -1, STR_LIT("string16")}},
+	{Type_Basic, {Basic_cstring16,         BasicFlag_String,                          -1, STR_LIT("cstring16")}},
+
+
 	{Type_Basic, {Basic_any,               0,                                         16, STR_LIT("any")}},
 
 	{Type_Basic, {Basic_typeid,            0,                                          8, STR_LIT("typeid")}},
@@ -591,8 +602,12 @@ gb_global Type *t_uint            = &basic_types[Basic_uint];
 gb_global Type *t_uintptr         = &basic_types[Basic_uintptr];
 
 gb_global Type *t_rawptr          = &basic_types[Basic_rawptr];
+
 gb_global Type *t_string          = &basic_types[Basic_string];
 gb_global Type *t_cstring         = &basic_types[Basic_cstring];
+gb_global Type *t_string16        = &basic_types[Basic_string16];
+gb_global Type *t_cstring16       = &basic_types[Basic_cstring16];
+
 gb_global Type *t_any             = &basic_types[Basic_any];
 
 gb_global Type *t_typeid          = &basic_types[Basic_typeid];
@@ -630,6 +645,8 @@ gb_global Type *t_untyped_uninit     = &basic_types[Basic_UntypedUninit];
 
 gb_global Type *t_u8_ptr       = nullptr;
 gb_global Type *t_u8_multi_ptr = nullptr;
+gb_global Type *t_u16_ptr       = nullptr;
+gb_global Type *t_u16_multi_ptr = nullptr;
 gb_global Type *t_int_ptr      = nullptr;
 gb_global Type *t_i64_ptr      = nullptr;
 gb_global Type *t_f64_ptr      = nullptr;
@@ -1292,6 +1309,14 @@ gb_internal bool is_type_string(Type *t) {
 	}
 	return false;
 }
+gb_internal bool is_type_string16(Type *t) {
+	t = base_type(t);
+	if (t == nullptr) { return false; }
+	if (t->kind == Type_Basic) {
+		return t->Basic.kind == Basic_string16;
+	}
+	return false;
+}
 gb_internal bool is_type_cstring(Type *t) {
 	t = base_type(t);
 	if (t == nullptr) { return false; }
@@ -1300,6 +1325,14 @@ gb_internal bool is_type_cstring(Type *t) {
 	}
 	return false;
 }
+gb_internal bool is_type_cstring16(Type *t) {
+	t = base_type(t);
+	if (t == nullptr) { return false; }
+	if (t->kind == Type_Basic) {
+		return t->Basic.kind == Basic_cstring16;
+	}
+	return false;
+}
 gb_internal bool is_type_typed(Type *t) {
 	t = base_type(t);
 	if (t == nullptr) { return false; }
@@ -1429,6 +1462,12 @@ gb_internal bool is_type_u8(Type *t) {
 	}
 	return false;
 }
+gb_internal bool is_type_u16(Type *t) {
+	if (t->kind == Type_Basic) {
+		return t->Basic.kind == Basic_u16;
+	}
+	return false;
+}
 gb_internal bool is_type_array(Type *t) {
 	t = base_type(t);
 	if (t == nullptr) { return false; }
@@ -1690,6 +1729,39 @@ gb_internal bool is_type_rune_array(Type *t) {
 	return false;
 }
 
+gb_internal bool is_type_u16_slice(Type *t) {
+	t = base_type(t);
+	if (t == nullptr) { return false; }
+	if (t->kind == Type_Slice) {
+		return is_type_u16(t->Slice.elem);
+	}
+	return false;
+}
+gb_internal bool is_type_u16_array(Type *t) {
+	t = base_type(t);
+	if (t == nullptr) { return false; }
+	if (t->kind == Type_Array) {
+		return is_type_u16(t->Array.elem);
+	}
+	return false;
+}
+gb_internal bool is_type_u16_ptr(Type *t) {
+	t = base_type(t);
+	if (t == nullptr) { return false; }
+	if (t->kind == Type_Pointer) {
+		return is_type_u16(t->Slice.elem);
+	}
+	return false;
+}
+gb_internal bool is_type_u16_multi_ptr(Type *t) {
+	t = base_type(t);
+	if (t == nullptr) { return false; }
+	if (t->kind == Type_MultiPointer) {
+		return is_type_u16(t->Slice.elem);
+	}
+	return false;
+}
+
 
 gb_internal bool is_type_array_like(Type *t) {
 	return is_type_array(t) || is_type_enumerated_array(t);
@@ -2109,7 +2181,7 @@ gb_internal bool is_type_indexable(Type *t) {
 	Type *bt = base_type(t);
 	switch (bt->kind) {
 	case Type_Basic:
-		return bt->Basic.kind == Basic_string;
+		return bt->Basic.kind == Basic_string || bt->Basic.kind == Basic_string16;
 	case Type_Array:
 	case Type_Slice:
 	case Type_DynamicArray:
@@ -2129,7 +2201,7 @@ gb_internal bool is_type_sliceable(Type *t) {
 	Type *bt = base_type(t);
 	switch (bt->kind) {
 	case Type_Basic:
-		return bt->Basic.kind == Basic_string;
+		return bt->Basic.kind == Basic_string || bt->Basic.kind == Basic_string16;
 	case Type_Array:
 	case Type_Slice:
 	case Type_DynamicArray:
@@ -2376,6 +2448,7 @@ gb_internal bool type_has_nil(Type *t) {
 		case Basic_any:
 			return true;
 		case Basic_cstring:
+		case Basic_cstring16:
 			return true;
 		case Basic_typeid:
 			return true;
@@ -2443,8 +2516,9 @@ gb_internal bool is_type_comparable(Type *t) {
 		case Basic_rune:
 			return true;
 		case Basic_string:
-			return true;
 		case Basic_cstring:
+		case Basic_string16:
+		case Basic_cstring16:
 			return true;
 		case Basic_typeid:
 			return true;
@@ -3774,10 +3848,12 @@ gb_internal i64 type_size_of(Type *t) {
 	if (t->kind == Type_Basic) {
 		GB_ASSERT_MSG(is_type_typed(t), "%s", type_to_string(t));
 		switch (t->Basic.kind) {
-		case Basic_string:  size = 2*build_context.int_size; break;
-		case Basic_cstring: size = build_context.ptr_size;   break;
-		case Basic_any:     size = 16;                       break;
-		case Basic_typeid:  size = 8;                        break;
+		case Basic_string:    size = 2*build_context.int_size; break;
+		case Basic_cstring:   size = build_context.ptr_size;   break;
+		case Basic_string16:  size = 2*build_context.int_size; break;
+		case Basic_cstring16: size = build_context.ptr_size;   break;
+		case Basic_any:       size = 16;                       break;
+		case Basic_typeid:    size = 8;                        break;
 
 		case Basic_int: case Basic_uint:
 			size = build_context.int_size;
@@ -3837,10 +3913,12 @@ gb_internal i64 type_align_of_internal(Type *t, TypePath *path) {
 	case Type_Basic: {
 		GB_ASSERT(is_type_typed(t));
 		switch (t->Basic.kind) {
-		case Basic_string:  return build_context.int_size;
-		case Basic_cstring: return build_context.ptr_size;
-		case Basic_any:     return 8;
-		case Basic_typeid:  return 8;
+		case Basic_string:    return build_context.int_size;
+		case Basic_cstring:   return build_context.ptr_size;
+		case Basic_string16:  return build_context.int_size;
+		case Basic_cstring16: return build_context.ptr_size;
+		case Basic_any:       return 8;
+		case Basic_typeid:    return 8;
 
 		case Basic_int: case Basic_uint:
 			return build_context.int_size;
@@ -4088,10 +4166,12 @@ gb_internal i64 type_size_of_internal(Type *t, TypePath *path) {
 			return size;
 		}
 		switch (kind) {
-		case Basic_string:  return 2*build_context.int_size;
-		case Basic_cstring: return build_context.ptr_size;
-		case Basic_any:     return 16;
-		case Basic_typeid:  return 8;
+		case Basic_string:    return 2*build_context.int_size;
+		case Basic_cstring:   return build_context.ptr_size;
+		case Basic_string16:  return 2*build_context.int_size;
+		case Basic_cstring16: return build_context.ptr_size;
+		case Basic_any:       return 16;
+		case Basic_typeid:    return 8;
 
 		case Basic_int: case Basic_uint:
 			return build_context.int_size;
@@ -4320,6 +4400,15 @@ gb_internal i64 type_offset_of(Type *t, i64 index, Type **field_type_) {
 				if (field_type_) *field_type_ = t_int;
 				return build_context.int_size; // len
 			}
+		} else if (t->Basic.kind == Basic_string16) {
+			switch (index) {
+			case 0:
+				if (field_type_) *field_type_ = t_u16_ptr;
+				return 0;                      // data
+			case 1:
+				if (field_type_) *field_type_ = t_int;
+				return build_context.int_size; // len
+			}
 		} else if (t->Basic.kind == Basic_any) {
 			switch (index) {
 			case 0:
@@ -4396,6 +4485,11 @@ gb_internal i64 type_offset_of_from_selection(Type *type, Selection sel) {
 					case 0: t = t_rawptr; break;
 					case 1: t = t_int;    break;
 					}
+				} else if (t->Basic.kind == Basic_string16) {
+					switch (index) {
+					case 0: t = t_rawptr; break;
+					case 1: t = t_int;    break;
+					}
 				} else if (t->Basic.kind == Basic_any) {
 					switch (index) {
 					case 0: t = t_rawptr; break;
@@ -4637,6 +4731,11 @@ gb_internal Type *type_internal_index(Type *t, isize index) {
 					GB_ASSERT(index == 0 || index == 1);
 					return index == 0 ? t_u8_ptr : t_int;
 				}
+			case Basic_string16:
+				{
+					GB_ASSERT(index == 0 || index == 1);
+					return index == 0 ? t_u16_ptr : t_int;
+				}
 			case Basic_any:
 				{
 					GB_ASSERT(index == 0 || index == 1);