checker: fix fixed array with const unint type size (fix #10826) (#10853)

vlib/v/checker/checker.v

@@ -4379,7 +4379,8 @@ pub fn (mut c Checker) array_init(mut array_init ast.ArrayInit) ast.Type {
 			}
 		}
 		if fixed_size <= 0 {
-			c.error('fixed size cannot be zero or negative', init_expr.position())
+			c.error('fixed size cannot be zero or negative (fixed_size: $fixed_size)',
+				init_expr.position())
 		}
 		idx := c.table.find_or_register_array_fixed(array_init.elem_type, int(fixed_size),
 			init_expr)

vlib/v/checker/comptime_const_eval.v

@@ -55,6 +55,34 @@ fn eval_comptime_const_expr(expr ast.Expr, nlevel int) ?ast.ComptTimeConstValue
 						return none
 					}
 				}
+			} else if left is u64 && right is i64 {
+				match expr.op {
+					.plus { return i64(left) + i64(right) }
+					.minus { return i64(left) - i64(right) }
+					.mul { return i64(left) * i64(right) }
+					.div { return i64(left) / i64(right) }
+					.mod { return i64(left) % i64(right) }
+					.xor { return i64(left) ^ i64(right) }
+					.pipe { return i64(left) | i64(right) }
+					.amp { return i64(left) & i64(right) }
+					.left_shift { return i64(left) << i64(right) }
+					.right_shift { return i64(left) >> i64(right) }
+					else { return none }
+				}
+			} else if left is i64 && right is u64 {
+				match expr.op {
+					.plus { return i64(left) + i64(right) }
+					.minus { return i64(left) - i64(right) }
+					.mul { return i64(left) * i64(right) }
+					.div { return i64(left) / i64(right) }
+					.mod { return i64(left) % i64(right) }
+					.xor { return i64(left) ^ i64(right) }
+					.pipe { return i64(left) | i64(right) }
+					.amp { return i64(left) & i64(right) }
+					.left_shift { return i64(left) << i64(right) }
+					.right_shift { return i64(left) >> i64(right) }
+					else { return none }
+				}
 			} else if left is u64 && right is u64 {
 				match expr.op {
 					.plus { return left + right }

vlib/v/checker/tests/fixed_array_size_err.out

@@ -1,11 +1,11 @@
-vlib/v/checker/tests/fixed_array_size_err.vv:4:8: error: fixed size cannot be zero or negative
-    2 |
+vlib/v/checker/tests/fixed_array_size_err.vv:4:8: error: fixed size cannot be zero or negative (fixed_size: -1)
+    2 | 
     3 | fn main() {
     4 |     a := [size]int{}
       |           ~~~~
     5 |     b := [0]byte{}
     6 |     println(a)
-vlib/v/checker/tests/fixed_array_size_err.vv:5:8: error: fixed size cannot be zero or negative
+vlib/v/checker/tests/fixed_array_size_err.vv:5:8: error: fixed size cannot be zero or negative (fixed_size: 0)
     3 | fn main() {
     4 |     a := [size]int{}
     5 |     b := [0]byte{}

vlib/v/tests/fixed_array_const_size_test.v

@@ -1,5 +1,6 @@
 const (
-	size = 5
+	size     = 5
+	u64_size = u64(5)
 )
 
 struct Foo {
@@ -13,3 +14,33 @@ fn test_fixed_array_const_size() {
 		bar: [byte(0), 0, 0, 0, 0]!
 	}
 }
+
+fn test_fixed_array_const_u64_size() {
+	a := [2 * u64_size]f64{}
+	println(a)
+	assert '$a' == '[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]'
+}
+
+const n = u64(5_000)
+
+const nn = 5_000
+
+fn test_u64_const_used_as_fixed_array_size() {
+	mut a := [2 * n]f64{}
+	dump(a.len)
+	assert a.len == 10000
+
+	mut b := [n * 2]f64{}
+	dump(b.len)
+	assert b.len == 10000
+}
+
+fn test_int_const_used_as_fixed_array_size() {
+	mut aa := [2 * nn]f64{}
+	dump(aa.len)
+	assert aa.len == 10_000
+
+	mut bb := [nn * 2]f64{}
+	dump(bb.len)
+	assert aa.len == 10_000
+}