rust/tests/ui/used_underscore_binding.rs
2018-10-06 09:43:08 -07:00

105 lines
2.6 KiB
Rust

// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
#![feature(tool_lints)]
#![warn(clippy::all)]
#![allow(clippy::blacklisted_name)]
#![warn(clippy::used_underscore_binding)]
macro_rules! test_macro {
() => {{
let _foo = 42;
_foo + 1
}}
}
/// Test that we lint if we use a binding with a single leading underscore
fn prefix_underscore(_foo: u32) -> u32 {
_foo + 1
}
/// Test that we lint if we use a `_`-variable defined outside within a macro expansion
fn in_macro(_foo: u32) {
println!("{}", _foo);
assert_eq!(_foo, _foo);
test_macro!() + 1;
}
// Struct for testing use of fields prefixed with an underscore
struct StructFieldTest {
_underscore_field: u32,
}
/// Test that we lint the use of a struct field which is prefixed with an underscore
fn in_struct_field() {
let mut s = StructFieldTest { _underscore_field: 0 };
s._underscore_field += 1;
}
/// Test that we do not lint if the underscore is not a prefix
fn non_prefix_underscore(some_foo: u32) -> u32 {
some_foo + 1
}
/// Test that we do not lint if we do not use the binding (simple case)
fn unused_underscore_simple(_foo: u32) -> u32 {
1
}
/// Test that we do not lint if we do not use the binding (complex case). This checks for
/// compatibility with the built-in `unused_variables` lint.
fn unused_underscore_complex(mut _foo: u32) -> u32 {
_foo += 1;
_foo = 2;
1
}
///Test that we do not lint for multiple underscores
fn multiple_underscores(__foo: u32) -> u32 {
__foo + 1
}
// Non-variable bindings with preceding underscore
fn _fn_test() {}
struct _StructTest;
enum _EnumTest {
_Empty,
_Value(_StructTest)
}
/// Test that we do not lint for non-variable bindings
fn non_variables() {
_fn_test();
let _s = _StructTest;
let _e = match _EnumTest::_Value(_StructTest) {
_EnumTest::_Empty => 0,
_EnumTest::_Value(_st) => 1,
};
let f = _fn_test;
f();
}
fn main() {
let foo = 0u32;
// tests of unused_underscore lint
let _ = prefix_underscore(foo);
in_macro(foo);
in_struct_field();
// possible false positives
let _ = non_prefix_underscore(foo);
let _ = unused_underscore_simple(foo);
let _ = unused_underscore_complex(foo);
let _ = multiple_underscores(foo);
non_variables();
}