vfmt: keep `vproto.Name`, when current module is `proto`

vlib/builtin/string.v

@@ -46,7 +46,7 @@ pub struct string {
 pub:
 	str byteptr // points to a C style 0 terminated string of bytes.
 	len int // the length of the .str field, excluding the ending 0 byte. It is always equal to strlen(.str).
-mut:    
+mut:
 	is_lit int
 }
 // mut:
@@ -157,7 +157,7 @@ pub fn cstring_to_vstring(cstr byteptr) string {
 
 pub fn (s string) replace_once(rep, with string) string {
 	index := s.index(rep) or {
-		return s
+		return s.clone()
 	}
 	return s.substr(0, index) + with + s.substr(index + rep.len, s.len)
 }

vlib/v/fmt/fmt.v

@@ -676,6 +676,15 @@ pub fn (mut f Fmt) prefix_expr_cast_expr(fexpr ast.Expr) {
 
 pub fn (f &Fmt) type_to_str(t table.Type) string {
 	mut res := f.table.type_to_str(t)
+	map_prefix := 'map[string]'
+	cur_mod := f.cur_mod + '.'
+	has_map_prefix := res.starts_with(map_prefix)
+	if has_map_prefix {
+		res = res.replace(map_prefix, '')
+	}
+	no_symbols := res.trim_left('&[]')
+	should_shorten := no_symbols.starts_with(cur_mod)
+	//
 	for res.ends_with('_ptr') {
 		// type_ptr => &type
 		res = res[0..res.len - 4]
@@ -686,12 +695,18 @@ pub fn (f &Fmt) type_to_str(t table.Type) string {
 		prefix := '[]fixed_'
 		res = res[prefix.len..]
 		last_underscore_idx := res.last_index('_') or {
-			return '[]' + res.replace(f.cur_mod + '.', '')
+			return '[]' + if should_shorten { res.replace_once(cur_mod, '') } else { res }
 		}
 		limit := res[last_underscore_idx + 1..]
 		res = '[' + limit + ']' + res[..last_underscore_idx]
 	}
-	return res.replace(f.cur_mod + '.', '')
+	if should_shorten {
+		res = res.replace_once(cur_mod, '')
+	}
+	if has_map_prefix {
+		res = map_prefix + res
+	}
+	return res
 }
 
 pub fn (mut f Fmt) expr(node ast.Expr) {

vlib/v/fmt/tests/proto_module_importing_vproto_keep.vv

@@ -0,0 +1,23 @@
+module proto
+
+import vproto
+
+struct Xyz {
+	x int
+}
+
+struct Abcde {
+	f1 vproto.Xyz
+	f2 &vproto.Xyz
+	f3 []vproto.Xyz
+	f4 []&vproto.Xyz
+	f5 map[string]vproto.Xyz
+	f6 map[string]&vproto.Xyz
+	//
+	p1 Xyz
+	p2 &Xyz
+	p3 []Xyz
+	p4 []&Xyz
+	p5 map[string]Xyz
+	p6 map[string]&Xyz
+}