gen: fix autogenerated print methods for vargs

vlib/v/gen/cgen.v

@@ -3486,7 +3486,7 @@ fn (mut g Gen) gen_str_for_type_with_styp(typ table.Type, styp string) string {
 	if typ.flag_is(.variadic) {
 		varg_already_generated_key := 'varg_$already_generated_key'
 		if varg_already_generated_key !in g.str_types {
-			g.gen_str_for_varg(styp, str_fn_name)
+			g.gen_str_for_varg(styp, str_fn_name, sym_has_str_method)
 			g.str_types << varg_already_generated_key
 		}
 		return 'varg_$str_fn_name'
@@ -3762,13 +3762,18 @@ fn (mut g Gen) gen_str_for_map(info table.Map, styp, str_fn_name string) {
 	g.auto_str_funcs.writeln('}')
 }
 
-fn (mut g Gen) gen_str_for_varg(styp, str_fn_name string) {
+fn (mut g Gen) gen_str_for_varg(styp, str_fn_name string, has_str_method bool) {
 	g.definitions.writeln('string varg_${str_fn_name}(varg_$styp it); // auto')
 	g.auto_str_funcs.writeln('string varg_${str_fn_name}(varg_$styp it) {')
 	g.auto_str_funcs.writeln('\tstrings__Builder sb = strings__new_builder(it.len);')
 	g.auto_str_funcs.writeln('\tstrings__Builder_write(&sb, tos_lit("["));')
 	g.auto_str_funcs.writeln('\tfor(int i=0; i<it.len; i++) {')
-	g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i], 0));')
+	if has_str_method {
+		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i]));')
+	}else{
+		// autogenerated str methods take the indent level as a second argument:
+		g.auto_str_funcs.writeln('\t\tstrings__Builder_write(&sb, ${str_fn_name}(it.args[i], 0));')
+	}
 	g.auto_str_funcs.writeln('\t\tif (i < it.len-1) {')
 	g.auto_str_funcs.writeln('\t\t\tstrings__Builder_write(&sb, tos_lit(", "));')
 	g.auto_str_funcs.writeln('\t\t}')

vlib/v/tests/vargs_auto_str_method_and_println_test.v

@@ -0,0 +1,44 @@
+module main
+
+fn test_autoprint_string_vargs() {
+	add_s('a')
+	assert true
+	add_s('a', 'b', 'c')
+	assert true
+}
+
+fn add_s(column string, other_columns ...string) {
+	println(column)
+	println(other_columns)
+}
+
+//
+fn test_autoprint_int_vargs() {
+	add_i(1)
+	assert true
+	add_i(1, 2, 3)
+	assert true
+}
+
+fn add_i(column int, other_columns ...int) {
+	println(column)
+	println(other_columns)
+}
+
+//
+struct Point {
+	x int
+	y int
+}
+
+fn test_autoprint_struct_vargs() {
+	add_point(Point{1, 2})
+	assert true
+	add_point(Point{1, 2}, Point{3, 4}, Point{5, 6})
+	assert true
+}
+
+fn add_point(column Point, other_columns ...Point) {
+	println(column)
+	println(other_columns)
+}