fmt: fix bug of disappearing `pub` in struct decl (#8777)

vlib/v/fmt/tests/structs_expected.vv

@@ -7,6 +7,12 @@ struct User {
 	very_long_type_field2 very_loooooooong_type // long
 }
 
+struct FamousUser {
+	User
+pub:
+	aka string
+}
+
 struct Foo {
 	field1 int    // f1
 	field2 string // f2

vlib/v/fmt/tests/structs_input.vv

@@ -7,6 +7,12 @@ struct User {
 	very_long_type_field2 very_loooooooong_type // long
 }
 
+struct FamousUser {
+pub:
+	User
+	aka string
+}
+
 struct Foo {
 	field1 int // f1
 	field2 string // f2

vlib/v/parser/struct.v

@@ -121,7 +121,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 						return ast.StructDecl{}
 					}
 					p.next()
-					pub_mut_pos = fields.len
+					pub_mut_pos = ast_fields.len
 					is_field_pub = true
 					is_field_mut = true
 					is_field_global = false
@@ -130,7 +130,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 						p.error('redefinition of `pub` section')
 						return ast.StructDecl{}
 					}
-					pub_pos = fields.len
+					pub_pos = ast_fields.len
 					is_field_pub = true
 					is_field_mut = false
 					is_field_global = false
@@ -143,7 +143,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 				}
 				p.next()
 				p.check(.colon)
-				mut_pos = fields.len
+				mut_pos = ast_fields.len
 				is_field_pub = false
 				is_field_mut = true
 				is_field_global = false
@@ -154,7 +154,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 				}
 				p.next()
 				p.check(.colon)
-				global_pos = fields.len
+				global_pos = ast_fields.len
 				is_field_pub = true
 				is_field_mut = true
 				is_field_global = true
@@ -165,7 +165,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 				}
 				p.next()
 				p.check(.colon)
-				module_pos = fields.len
+				module_pos = ast_fields.len
 				is_field_pub = false
 				is_field_mut = false
 				is_field_global = false
@@ -320,11 +320,11 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 		is_pub: is_pub
 		fields: ast_fields
 		pos: start_pos.extend_with_last_line(name_pos, last_line)
-		mut_pos: mut_pos - embeds.len
-		pub_pos: pub_pos - embeds.len
-		pub_mut_pos: pub_mut_pos - embeds.len
-		global_pos: global_pos - embeds.len
-		module_pos: module_pos - embeds.len
+		mut_pos: mut_pos
+		pub_pos: pub_pos
+		pub_mut_pos: pub_mut_pos
+		global_pos: global_pos
+		module_pos: module_pos
 		language: language
 		is_union: is_union
 		attrs: attrs