checker: allow casted integeral types in match ranges (#19572)

vlib/v/checker/match.v

@@ -166,6 +166,11 @@ fn (mut c Checker) get_comptime_number_value(mut expr ast.Expr) ?i64 {
 	if mut expr is ast.IntegerLiteral {
 		return expr.val.i64()
 	}
+	if mut expr is ast.CastExpr {
+		if mut expr.expr is ast.IntegerLiteral {
+			return expr.expr.val.i64()
+		}
+	}
 	if mut expr is ast.Ident {
 		has_expr_mod_in_name := expr.name.contains('.')
 		expr_name := if has_expr_mod_in_name { expr.name } else { '${expr.mod}.${expr.name}' }

vlib/v/checker/tests/match_cast_cond_not_same_range_cast_type_err.out

@@ -0,0 +1,10 @@
+vlib/v/checker/tests/match_cast_cond_not_same_range_cast_type_err.vv:7:2: error: the range type and the match condition type should match
+    5 | c := u8(3)
+    6 | match c {
+    7 |     a...b { println('1...5') }
+      |     ~~~~~
+    8 |     else { println('not 1...5') }
+    9 | }
+Details: 
+match condition type: u8
+          range type: u16

vlib/v/checker/tests/match_cast_cond_not_same_range_cast_type_err.vv

@@ -0,0 +1,9 @@
+const (
+	a = u16(1)
+	b = u16(5)
+)
+c := u8(3)
+match c {
+	a...b { println('1...5') }
+	else { println('not 1...5') }
+}

vlib/v/checker/tests/match_ranges_not_same_cast_err.out

@@ -0,0 +1,10 @@
+vlib/v/checker/tests/match_ranges_not_same_cast_err.vv:7:2: error: the low and high parts of a range expression, should have matching types
+    5 | c := u16(3)
+    6 | match c {
+    7 |     a...b { println('1...5') }
+      |     ~~~~~
+    8 |     else { println('not 1...5') }
+    9 | }
+Details: 
+ low part type: u16
+high part type: u8

vlib/v/checker/tests/match_ranges_not_same_cast_err.vv

@@ -0,0 +1,9 @@
+const (
+	a = u16(1)
+	b = u8(5)
+)
+c := u16(3)
+match c {
+	a...b { println('1...5') }
+	else { println('not 1...5') }
+}

vlib/v/tests/match_const_range_test.v

@@ -1,13 +1,16 @@
 const (
-	start        = 1
+	start           = 1
-	start_2      = 4
+	start_2         = 4
-	end          = 3
+	end             = 3
-	end_2        = 8
+	end_2           = 8
 	//
-	start_rune   = `a`
+	start_rune      = `a`
-	start_2_rune = `d`
+	start_2_rune    = `d`
-	end_rune     = `c`
+	end_rune        = `c`
-	end_2_rune   = `i`
+	end_2_rune      = `i`
+	//
+	start_cast_expr = u16(1)
+	end_cast_expr   = u16(5)
 )
 
 fn test_match_int_const_ranges() {
@@ -63,3 +66,13 @@ fn test_match_expr_rune_const_ranges() {
 	}
 	assert results == [1, 1, 1, 2, 2, 3, 3, 3, 3, 4, 4]
 }
+
+fn test_match_expr_integer_cast_const_ranges() {
+	c := u16(3)
+	match c {
+		start_cast_expr...end_cast_expr {
+			assert c == u16(3)
+		}
+		else {}
+	}
+}