parser: allow for variable name using keyword 'type' (vlang#22512)

vlib/v/parser/expr.v

@@ -51,7 +51,7 @@ fn (mut p Parser) check_expr(precedence int) !ast.Expr {
 			if p.peek_tok.kind in [.lpar, .lsbr] && p.peek_tok.is_next_to(p.tok) {
 				node = p.call_expr(p.language, p.mod)
 			} else {
-				ident := p.ident(ast.Language.v)
+				ident := p.ident(.v)
 				node = ident
 				if p.peek_tok.kind != .assign && (p.inside_if_cond || p.inside_match) {
 					p.mark_var_as_used(ident.name)
@@ -519,8 +519,14 @@ fn (mut p Parser) check_expr(precedence int) !ast.Expr {
 					p.next()
 					return p.struct_init('', .anon, false)
 				}
-			}
-			if p.tok.kind != .eof && !(p.tok.kind == .rsbr && p.inside_asm) {
+			} else if p.tok.kind == .key_type {
+				// variable name: type
+				ident := p.ident(.v)
+				node = ident
+				p.mark_var_as_used(ident.name)
+				p.add_defer_var(ident)
+				p.is_stmt_ident = is_stmt_ident
+			} else if p.tok.kind != .eof && !(p.tok.kind == .rsbr && p.inside_asm) {
 				// eof should be handled where it happens
 				return error('none')
 				// return p.unexpected(prepend_msg: 'invalid expression: ')
@@ -938,7 +944,7 @@ fn (mut p Parser) lambda_expr() ?ast.LambdaExpr {
 			if p.tok.kind == .eof {
 				break
 			}
-			ident := p.ident(ast.Language.v)
+			ident := p.ident(.v)
 			if p.scope.known_var(ident.name) {
 				p.error_with_pos('redefinition of parameter `${ident.name}`', ident.pos)
 			}

vlib/v/parser/parser.v

@@ -2326,7 +2326,7 @@ fn (mut p Parser) ident(language ast.Language) ast.Ident {
 	if is_volatile {
 		p.next()
 	}
-	if p.tok.kind != .name {
+	if p.tok.kind !in [.name, .key_type] {
 		if is_mut || is_static || is_volatile {
 			p.error_with_pos('the `${modifier_kind}` keyword is invalid here', mut_pos)
 		} else {
@@ -2621,7 +2621,7 @@ fn (mut p Parser) name_expr() ast.Expr {
 		is_known_var := p.scope.known_var(p.tok.lit)
 		if is_known_var {
 			p.mark_var_as_used(p.tok.lit)
-			return p.ident(ast.Language.v)
+			return p.ident(.v)
 		} else {
 			type_pos := p.tok.pos()
 			typ := p.parse_type()

vlib/v/tests/var_name_using_type_test.v

@@ -0,0 +1,22 @@
+fn info(type int) int {
+	return type
+}
+
+fn print_info() {
+	for type in [1, 2, 3] {
+		println(type)
+	}
+}
+
+fn test_var_name_using_type() {
+	ret := info(22)
+	println(ret)
+	assert ret == 22
+
+	type := 33
+	println(type)
+	assert type == 33
+
+	print_info()
+	assert true
+}