From 405635338181596b76d2389f7ae2191e589fe748 Mon Sep 17 00:00:00 2001
From: Turiiya <34311583+ttytm@users.noreply.github.com>
Date: Sun, 7 Apr 2024 16:05:13 +0200
Subject: [PATCH] parser, checker: improve the error message for an unknown
 type (#21207)

---
 vlib/v/checker/tests/is_type_not_exist.out | 41 +++++++++++++++-------
 vlib/v/checker/tests/is_type_not_exist.vv  | 19 ++++++++++
 vlib/v/parser/parse_type.v                 |  8 ++---
 3 files changed, 52 insertions(+), 16 deletions(-)

diff --git a/vlib/v/checker/tests/is_type_not_exist.out b/vlib/v/checker/tests/is_type_not_exist.out
index 3803649e8..8c7dd944b 100644
--- a/vlib/v/checker/tests/is_type_not_exist.out
+++ b/vlib/v/checker/tests/is_type_not_exist.out
@@ -1,14 +1,31 @@
-vlib/v/checker/tests/is_type_not_exist.vv:8:10: error: is: type `SomethingThatDontExist` does not exist
-    6 | 
-    7 | fn fn_with_sum_type_param(i Integer) {
-    8 |     if i is SomethingThatDontExist {
+vlib/v/checker/tests/is_type_not_exist.vv:10:10: error: is: type `testmod.SomethingThatDontExist` does not exist
+    8 | 
+    9 | fn fn_with_sum_type_param(i Integer) {
+   10 |     if i is SomethingThatDontExist {
       |             ~~~~~~~~~~~~~~~~~~~~~~
-    9 |         println('It should fail !')
-   10 |     }
-vlib/v/checker/tests/is_type_not_exist.vv:8:10: error: `Integer` has no variant `SomethingThatDontExist`
-    6 | 
-    7 | fn fn_with_sum_type_param(i Integer) {
-    8 |     if i is SomethingThatDontExist {
+   11 |         println('It should fail !')
+   12 |     }
+vlib/v/checker/tests/is_type_not_exist.vv:10:10: error: `testmod.Integer` has no variant `testmod.SomethingThatDontExist`
+    8 | 
+    9 | fn fn_with_sum_type_param(i Integer) {
+   10 |     if i is SomethingThatDontExist {
       |             ~~~~~~~~~~~~~~~~~~~~~~
-    9 |         println('It should fail !')
-   10 |     }
+   11 |         println('It should fail !')
+   12 |     }
+vlib/v/checker/tests/is_type_not_exist.vv:29:11: error: is: type `testmod.empty_foo` does not exist
+   27 |     _ := testmod.empty_foo
+   28 |     fb := Foobar(Foo{foo: 5})
+   29 |     if fb is testmod.empty_foo{}
+      |              ~~~~~~~
+   30 | }
+vlib/v/checker/tests/is_type_not_exist.vv:29:11: error: `testmod.Foobar` has no variant `testmod.empty_foo`
+   27 |     _ := testmod.empty_foo
+   28 |     fb := Foobar(Foo{foo: 5})
+   29 |     if fb is testmod.empty_foo{}
+      |              ~~~~~~~
+   30 | }
+vlib/v/checker/tests/is_type_not_exist.vv:1:1: error: project must include a `main` module or be a shared library (compile with `v -shared`)
+    1 | module testmod
+      | ^
+    2 | 
+    3 | type Integer = i8 | i16 | int | i64
diff --git a/vlib/v/checker/tests/is_type_not_exist.vv b/vlib/v/checker/tests/is_type_not_exist.vv
index e50859b34..6575f437c 100644
--- a/vlib/v/checker/tests/is_type_not_exist.vv
+++ b/vlib/v/checker/tests/is_type_not_exist.vv
@@ -1,3 +1,5 @@
+module testmod
+
 type Integer = i8 | i16 | int | i64
 
 fn main() {
@@ -9,3 +11,20 @@ fn fn_with_sum_type_param(i Integer) {
 		println('It should fail !')
 	}
 }
+
+struct Foo {
+	foo int
+}
+struct Bar {
+	bar i8
+}
+
+type Foobar = Foo | Bar
+
+const empty_foo = Foo{foo: 0}
+
+fn fn_with_module_const_type_is_expr() {
+	_ := testmod.empty_foo
+	fb := Foobar(Foo{foo: 5})
+	if fb is testmod.empty_foo{}
+}
diff --git a/vlib/v/parser/parse_type.v b/vlib/v/parser/parse_type.v
index 845aca777..b3f1d50f2 100644
--- a/vlib/v/parser/parse_type.v
+++ b/vlib/v/parser/parse_type.v
@@ -614,13 +614,13 @@ fn (mut p Parser) parse_any_type(language ast.Language, is_ptr bool, check_dot b
 		if mod in p.imports {
 			p.register_used_import(mod)
 			mod = p.imports[mod]
+			if p.tok.lit.len > 0 && !p.tok.lit[0].is_capital() {
+				p.error('imported types must start with a capital letter')
+				return 0
+			}
 		}
 		// prefix with full module
 		name = '${mod}.${p.tok.lit}'
-		if p.tok.lit.len > 0 && !p.tok.lit[0].is_capital() {
-			p.error('imported types must start with a capital letter')
-			return 0
-		}
 	} else if p.expr_mod != '' && !p.inside_generic_params {
 		// p.expr_mod is from the struct and not from the generic parameter
 		name = p.expr_mod + '.' + name
-- 
2.39.5