distinct type aliasing

compiler/parser/parser.odin

@@ -1477,6 +1477,19 @@ parse_struct :: proc(parser: ^Parser, name: token.Token, c_layout: bool) {
 	_ = finish_statement(parser)
 }
 
+parse_distinct :: proc(parser: ^Parser, name: token.Token) {
+	start := advance(parser)
+	child := parse_type(parser)
+	id := types.named(&parser.module.type_store, u32(parser.pkg), u32(name.symbol))
+	if !types.define_distinct(&parser.module.type_store, id, child) {
+		source.addf(parser.diagnostics, name.span, "duplicate type declaration '%s'", token_text(parser, name))
+	}
+	if !types.is_valid(child) {
+		source.add(parser.diagnostics, start.span, "distinct declarations require a backing type")
+	}
+	_ = finish_statement(parser)
+}
+
 decode_import_path :: proc(parser: ^Parser, tok: token.Token) -> string {
 	text := token_text(parser, tok)
 	if len(text) < 2 {
@@ -1588,6 +1601,10 @@ parse_top_level :: proc(parser: ^Parser) {
 		parse_struct(parser, name, current(parser).kind == .Keyword_C_Struct)
 		return
 	}
+	if operator.kind == .Colon_Colon && current(parser).kind == .Keyword_Distinct {
+		parse_distinct(parser, name)
+		return
+	}
 
 	expr := parse_expression(parser)
 	_ = ast.global_id(len(parser.module.globals))