checker: disallow matching type with primitive vars (#18084)

vlib/v/checker/match.v

@@ -198,6 +198,10 @@ fn (mut c Checker) match_exprs(mut node ast.MatchExpr, cond_type_sym ast.TypeSym
 				c.error('struct instances cannot be matched by type name, they can only be matched to other instances of the same struct type',
 					branch.pos)
 			}
+			if mut expr is ast.TypeNode && cond_sym.is_primitive() {
+				c.error('matching by type can only be done for sum types, generics, interfaces, `${node.cond}` is none of those',
+					branch.pos)
+			}
 			if mut expr is ast.RangeExpr {
 				// Allow for `match enum_value { 4..5 { } }`, even though usually int and enum values,
 				// are considered incompatible outside unsafe{}, and are not allowed to be compared directly

vlib/v/checker/tests/match_type_node_with_non_sum_type_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/match_type_node_with_non_sum_type_err.vv:5:3: error: matching by type can only be done for sum types, generics, interfaces, `b` is none of those
+    3 |
+    4 |     match b {
+    5 |         i64 { println('i64') }
+      |         ~~~
+    6 |         100 { println(100) }
+    7 |         else {}

vlib/v/checker/tests/match_type_node_with_non_sum_type_err.vv

@@ -0,0 +1,9 @@
+fn main() {
+	b := i64(100)
+
+	match b {
+		i64 { println('i64') }
+		100 { println(100) }
+		else {}
+	}
+}