string(buffer, len) cast

compiler/parser.v

@@ -2647,11 +2647,18 @@ fn (p mut Parser) cast(typ string) string {
 	p.expected_type = typ 
 	expr_typ := p.bool_expression()
 	p.expected_type = '' 
-	p.check(.rpar)
 	// `string(buffer)` => `tos2(buffer)`
+	// `string(buffer, len)` => `tos(buffer, len)`
 	if typ == 'string' && (expr_typ == 'byte*' || expr_typ == 'byteptr') {
+		if p.tok == .comma { 
+			p.check(.comma) 
+			p.cgen.set_placeholder(pos, 'tos(')
+			p.gen(', ') 
+			p.check_types(p.expression(), 'int') 
+		}  else { 
 			p.cgen.set_placeholder(pos, 'tos2(')
 		} 
+	}
 	// `string(234)` => error
 	else if typ == 'string' && expr_typ == 'int' {
 		p.error('cannot cast `$expr_typ` to `$typ`, use `str()` method instead')
@@ -2659,6 +2666,7 @@ fn (p mut Parser) cast(typ string) string {
 	else {
 		p.cgen.set_placeholder(pos, '($typ)(')
 	}
+	p.check(.rpar)
 	p.gen(')')
 	return typ
 }

vlib/builtin/string_test.v

@@ -318,3 +318,14 @@ fn test_interpolation() {
 	assert s == 'baz=baz' 
  
 } 
+
+fn test_bytes_to_string() {
+	mut buf := malloc(10) 
+	buf[0] = `h` 
+	buf[1] = `e` 
+	buf[2] = `l` 
+	buf[3] = `l` 
+	buf[4] = `o` 
+	assert string(buf) == 'hello' 
+	assert string(buf, 2) == 'he' 
+}