parser: fix invalid field name checking (fix #24279) (#24283)

Author: felipensp

vlib/v/parser/struct.v

@@ -218,6 +218,11 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 			}
 
 			if is_embed {
+				if p.peek_tok.kind == .dot && p.peek_tok.line_nr == p.peek_token(3).line_nr
+					&& p.peek_token(3).kind == .name {
+					p.error_with_pos('invalid field name', p.tok.pos())
+					return ast.StructDecl{}
+				}
 				// struct embedding
 				type_pos = p.tok.pos()
 				typ = p.parse_type()

vlib/v/parser/tests/invalid_field_name_err.out

@@ -0,0 +1,5 @@
+vlib/v/parser/tests/invalid_field_name_err.vv:2:2: error: invalid field name
+    1 | struct MyStruct { 
+    2 |     c.close int
+      |     ^
+    3 | }

vlib/v/parser/tests/invalid_field_name_err.vv

@@ -0,0 +1,3 @@
+struct MyStruct { 
+	c.close int
+}