checker: check div/mod by zero (#7256)

vlib/v/checker/checker.v

@@ -609,6 +609,27 @@ pub fn (mut c Checker) struct_init(mut struct_init ast.StructInit) table.Type {
 	return struct_init.typ
 }
 
+fn (mut c Checker) check_div_mod_by_zero(expr ast.Expr, op_kind token.Kind) {
+	match mut expr {
+		ast.FloatLiteral {
+			if expr.val.f64() == 0.0 {
+				oper := if op_kind == .div { 'division' } else { 'modulo' }
+				c.error('$oper by zero', expr.pos)
+			}
+		}
+		ast.IntegerLiteral {
+			if expr.val.int() == 0 {
+				oper := if op_kind == .div { 'division' } else { 'modulo' }
+				c.error('$oper by zero', expr.pos)
+			}
+		}
+		ast.CastExpr {
+			c.check_div_mod_by_zero(expr.expr, op_kind)
+		}
+		else {}
+	}
+}
+
 pub fn (mut c Checker) infix_expr(mut infix_expr ast.InfixExpr) table.Type {
 	// println('checker: infix expr(op $infix_expr.op.str())')
 	former_expected_type := c.expected_type
@@ -757,21 +778,7 @@ pub fn (mut c Checker) infix_expr(mut infix_expr ast.InfixExpr) table.Type {
 					}
 				}
 				if infix_expr.op in [.div, .mod] {
-					match mut infix_expr.right {
-						ast.FloatLiteral {
-							if infix_expr.right.val.f64() == 0.0 {
-								oper := if infix_expr.op == .div { 'division' } else { 'modulo' }
-								c.error('$oper by zero', infix_expr.right.pos)
-							}
-						}
-						ast.IntegerLiteral {
-							if infix_expr.right.val.int() == 0 {
-								oper := if infix_expr.op == .div { 'division' } else { 'modulo' }
-								c.error('$oper by zero', infix_expr.right.pos)
-							}
-						}
-						else {}
-					}
+					c.check_div_mod_by_zero(infix_expr.right, infix_expr.op)
 				}
 				return_type = promoted_type
 			}

vlib/v/checker/tests/div_mod_by_cast_zero_int_err.out

@@ -0,0 +1,40 @@
+vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv:2:21: error: division by zero
+    1 | fn main() {
+    2 |     println(u64(1)/u64(0))
+      |                        ^
+    3 |     println(u64(1)%u64(0))
+    4 |
+vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv:3:21: error: modulo by zero
+    1 | fn main() {
+    2 |     println(u64(1)/u64(0))
+    3 |     println(u64(1)%u64(0))
+      |                        ^
+    4 |
+    5 |     println(u32(1)/u32(0x0))
+vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv:5:21: error: division by zero
+    3 |     println(u64(1)%u64(0))
+    4 |
+    5 |     println(u32(1)/u32(0x0))
+      |                        ~~~
+    6 |     println(u32(1)%u32(0x0))
+    7 |
+vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv:6:21: error: modulo by zero
+    4 |
+    5 |     println(u32(1)/u32(0x0))
+    6 |     println(u32(1)%u32(0x0))
+      |                        ~~~
+    7 |
+    8 |     println(u16(1)/u16(0b0))
+vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv:8:21: error: division by zero
+    6 |     println(u32(1)%u32(0x0))
+    7 |
+    8 |     println(u16(1)/u16(0b0))
+      |                        ~~~
+    9 |     println(u16(1)%u16(0b0))
+   10 | }
+vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv:9:21: error: modulo by zero
+    7 |
+    8 |     println(u16(1)/u16(0b0))
+    9 |     println(u16(1)%u16(0b0))
+      |                        ~~~
+   10 | }

vlib/v/checker/tests/div_mod_by_cast_zero_int_err.vv

@@ -0,0 +1,10 @@
+fn main() {
+	println(u64(1)/u64(0))
+	println(u64(1)%u64(0))
+
+	println(u32(1)/u32(0x0))
+	println(u32(1)%u32(0x0))
+
+	println(u16(1)/u16(0b0))
+	println(u16(1)%u16(0b0))
+}

vlib/v/checker/tests/division_by_cast_zero_float_err.out

@@ -0,0 +1,12 @@
+vlib/v/checker/tests/division_by_cast_zero_float_err.vv:2:23: error: division by zero
+    1 | fn main() {
+    2 |     println(f32(1.0)/f32(0.0))
+      |                          ~~~
+    3 |     println(f64(1.0)/f64(0.0))
+    4 | }
+vlib/v/checker/tests/division_by_cast_zero_float_err.vv:3:23: error: division by zero
+    1 | fn main() {
+    2 |     println(f32(1.0)/f32(0.0))
+    3 |     println(f64(1.0)/f64(0.0))
+      |                          ~~~
+    4 | }

vlib/v/checker/tests/division_by_cast_zero_float_err.vv

@@ -0,0 +1,4 @@
+fn main() {
+	println(f32(1.0)/f32(0.0))
+	println(f64(1.0)/f64(0.0))
+}