cgen: fix code generation when 'in array init' is used as an if condition (fix #20300) (#20302)

Author: shove70

vlib/v/gen/c/infix.v

@@ -518,7 +518,9 @@ fn (mut g Gen) infix_expr_in_op(node ast.InfixExpr) {
 						expr: node.left
 						expr_type: ast.mktyp(node.left_type)
 					}
+					g.write('(')
 					g.gen_array_contains(node.right_type, node.right, elem_type, new_node_left)
+					g.write(')')
 					return
 				}
 			} else if elem_type_.sym.kind == .interface_ {
@@ -528,11 +530,15 @@ fn (mut g Gen) infix_expr_in_op(node ast.InfixExpr) {
 					expr: node.left
 					expr_type: ast.mktyp(node.left_type)
 				}
+				g.write('(')
 				g.gen_array_contains(node.right_type, node.right, elem_type, new_node_left)
+				g.write(')')
 				return
 			}
 		}
+		g.write('(')
 		g.gen_array_contains(node.right_type, node.right, node.left_type, node.left)
+		g.write(')')
 	} else if right.unaliased_sym.kind == .map {
 		g.write('_IN_MAP(')
 		if !left.typ.is_ptr() {
@@ -597,18 +603,24 @@ fn (mut g Gen) infix_expr_in_op(node ast.InfixExpr) {
 						expr: node.left
 						expr_type: ast.mktyp(node.left_type)
 					}
+					g.write('(')
 					g.gen_array_contains(node.right_type, node.right, elem_type, new_node_left)
+					g.write(')')
 					return
 				}
 			}
 		}
+		g.write('(')
 		g.gen_array_contains(node.right_type, node.right, node.left_type, node.left)
+		g.write(')')
 	} else if right.unaliased_sym.kind == .string {
+		g.write('(')
 		g.write('string_contains(')
 		g.expr(node.right)
 		g.write(', ')
 		g.expr(node.left)
 		g.write(')')
+		g.write(')')
 	}
 }
 

vlib/v/tests/if_expression_test.v

@@ -263,3 +263,13 @@ fn test_noreturn() {
 		assert_false_noreturn()
 	}
 }
+
+// for issue 20300
+// Phenomenon of issue:
+// infix expr generates wraparound parentheses, but misses the case where `array_contains()` is used.
+fn test_in_array_init() {
+	if 0 in []int{} {
+		assert false
+	}
+	assert true
+}