checker: tweak error messages for `or` block; use proper type names (#6377)

vlib/v/ast/ast.v

@@ -262,6 +262,7 @@ pub mut:
 	return_type   table.Type
 }
 
+// break, continue
 pub struct BranchStmt {
 pub:
 	tok token.Token

vlib/v/checker/checker.v

@@ -1509,12 +1509,6 @@ pub fn (mut c Checker) check_or_expr(mut or_expr ast.OrExpr, ret_type table.Type
 	}
 	mut last_stmt := or_expr.stmts[stmts_len - 1]
 	if ret_type != table.void_type {
-		if !(last_stmt is ast.Return || last_stmt is ast.BranchStmt || last_stmt is ast.ExprStmt) {
-			expected_type_name := c.table.get_type_symbol(ret_type).name
-			c.error('last statement in the `or {}` block should return `$expected_type_name`',
-				or_expr.pos)
-			return
-		}
 		match mut last_stmt {
 			ast.ExprStmt {
 				last_stmt.typ = c.expr(last_stmt.expr)
@@ -1523,8 +1517,8 @@ pub fn (mut c Checker) check_or_expr(mut or_expr ast.OrExpr, ret_type table.Type
 				if type_fits || is_panic_or_exit {
 					return
 				}
-				type_name := c.table.get_type_symbol(last_stmt.typ).name
-				expected_type_name := c.table.get_type_symbol(ret_type).name
+				type_name := c.table.type_to_str(last_stmt.typ)
+				expected_type_name := c.table.type_to_str(ret_type.clear_flag(.optional))
 				c.error('wrong return type `$type_name` in the `or {}` block, expected `$expected_type_name`',
 					last_stmt.pos)
 				return
@@ -1536,11 +1530,16 @@ pub fn (mut c Checker) check_or_expr(mut or_expr ast.OrExpr, ret_type table.Type
 					return
 				}
 			}
-			else {}
-		}
+			ast.Return {}
+			else {
+				expected_type_name := c.table.type_to_str(ret_type.clear_flag(.optional))
+				c.error('last statement in the `or {}` block should be an expression of type `$expected_type_name` or exit parent scope',
+					or_expr.pos)
 				return
 			}
 		}
+	}
+}
 
 fn is_expr_panic_or_exit(expr ast.Expr) bool {
 	match expr {

vlib/v/checker/tests/or_err.out

@@ -0,0 +1,14 @@
+vlib/v/checker/tests/or_err.vv:4:6: error: last statement in the `or {}` block should be an expression of type `&int` or exit parent scope
+    2 |     return none
+    3 | }
+    4 | a := f() or {
+      |      ~~~
+    5 |     {}
+    6 | }
+vlib/v/checker/tests/or_err.vv:11:2: error: wrong return type `rune` in the `or {}` block, expected `&int`
+    9 | }
+   10 | _ = f() or {
+   11 |     `.`
+      |     ~~~
+   12 | }
+   13 |

vlib/v/checker/tests/or_err.vv

@@ -0,0 +1,13 @@
+fn f() ?&int {
+	return none
+}
+a := f() or {
+	{}
+}
+_ = f() or {
+	a
+}
+_ = f() or {
+	`.`
+}
+

vlib/v/table/atypes.v

@@ -24,14 +24,19 @@ pub enum Language {
 	js
 }
 
+// Represents a type that only needs an identifier, e.g. int, array_int.
+// A pointer type `&T` would have a TypeSymbol `T`.
+// Note: For a Type, use Table.type_to_str(typ) not TypeSymbol.name.
+// Each TypeSymbol is entered into `Table.types`.
+// See also: Table.get_type_symbol.
 pub struct TypeSymbol {
 pub:
 	parent_idx  int
 pub mut:
 	info        TypeInfo
 	kind        Kind
-	name        string // the internal name of the type, i.e. `array_fixed_int_5`. See also .source_name below.
-	source_name string // the original source name of the type, i.e. `[5]int`. Do not use this for logic, but just for formatting/errors.
+	name        string // the internal name of the type or underlying type, i.e. `array_fixed_int_5`. See also .source_name below.
+	source_name string // the original source name of the type, i.e. `[5]int`.
 	methods     []Fn
 	mod         string
 	is_public   bool