From f59119485af01d1da73e3ae40366669febef7022 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20D=C3=A4schle?= <daniel.daeschle@gmail.com>
Date: Wed, 4 Aug 2021 17:14:16 +0200
Subject: [PATCH] v.parser: add check for existing type on sum type declaration
 (#11054)

---
 vlib/v/parser/parser.v                               | 8 +++++++-
 vlib/v/parser/tests/sum_type_exists_err.out          | 3 +++
 vlib/v/parser/tests/sum_type_exists_err.vv           | 1 +
 vlib/v/parser/tests/type_alias_existing_type_err.out | 8 ++++----
 4 files changed, 15 insertions(+), 5 deletions(-)
 create mode 100644 vlib/v/parser/tests/sum_type_exists_err.out
 create mode 100644 vlib/v/parser/tests/sum_type_exists_err.vv

diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index e17295e67c..ba75af9f07 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -3123,6 +3123,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 	p.check(.key_type)
 	end_pos := p.tok.position()
 	decl_pos := start_pos.extend(end_pos)
+	name_pos := p.tok.position()
 	name := p.check_name()
 	if name.len == 1 && name[0].is_capital() {
 		p.error_with_pos('single letter capital names are reserved for generic template types.',
@@ -3197,6 +3198,11 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 			}
 			is_public: is_pub
 		})
+		if typ == -1 {
+			p.error_with_pos('cannot register sum type `$name`, another type with this name exists',
+				name_pos)
+			return ast.SumTypeDecl{}
+		}
 		comments = p.eat_comments(same_line: true)
 		return ast.SumTypeDecl{
 			name: name
@@ -3233,7 +3239,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 	type_end_pos := p.prev_tok.position()
 	if idx == -1 {
 		p.error_with_pos('cannot register alias `$name`, another type with this name exists',
-			decl_pos.extend(type_alias_pos))
+			name_pos)
 		return ast.AliasTypeDecl{}
 	}
 	if idx == pidx {
diff --git a/vlib/v/parser/tests/sum_type_exists_err.out b/vlib/v/parser/tests/sum_type_exists_err.out
new file mode 100644
index 0000000000..99bbeafa8d
--- /dev/null
+++ b/vlib/v/parser/tests/sum_type_exists_err.out
@@ -0,0 +1,3 @@
+vlib/v/parser/tests/sum_type_exists_err.vv:1:6: error: cannot register sum type `Option`, another type with this name exists
+    1 | type Option = string | int
+      |      ~~~~~~
diff --git a/vlib/v/parser/tests/sum_type_exists_err.vv b/vlib/v/parser/tests/sum_type_exists_err.vv
new file mode 100644
index 0000000000..b9634c1bf2
--- /dev/null
+++ b/vlib/v/parser/tests/sum_type_exists_err.vv
@@ -0,0 +1 @@
+type Option = string | int
diff --git a/vlib/v/parser/tests/type_alias_existing_type_err.out b/vlib/v/parser/tests/type_alias_existing_type_err.out
index 6ea695f473..e3ada576e9 100644
--- a/vlib/v/parser/tests/type_alias_existing_type_err.out
+++ b/vlib/v/parser/tests/type_alias_existing_type_err.out
@@ -1,7 +1,7 @@
-vlib/v/parser/tests/type_alias_existing_type_err.vv:3:1: error: cannot register alias `Foo`, another type with this name exists
+vlib/v/parser/tests/type_alias_existing_type_err.vv:3:6: error: cannot register alias `Foo`, another type with this name exists
     1 | struct Foo{}
-    2 |
+    2 | 
     3 | type Foo = Foo
-      | ~~~~~~~~~~~~~~
-    4 |
+      |      ~~~
+    4 | 
     5 | fn main() {