rust/tests/ui/option_map_unit_fn.rs

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// 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.
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#![warn(clippy::option_map_unit_fn)]
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#![allow(unused)]
fn do_nothing<T>(_: T) {}
fn diverge<T>(_: T) -> ! {
panic!()
}
fn plus_one(value: usize) -> usize {
value + 1
}
struct HasOption {
field: Option<usize>,
}
impl HasOption {
fn do_option_nothing(self: &Self, value: usize) {}
fn do_option_plus_one(self: &Self, value: usize) -> usize {
value + 1
}
}
fn option_map_unit_fn() {
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let x = HasOption { field: Some(10) };
x.field.map(plus_one);
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let _: Option<()> = x.field.map(do_nothing);
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x.field.map(do_nothing);
x.field.map(do_nothing);
x.field.map(diverge);
let captured = 10;
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if let Some(value) = x.field {
do_nothing(value + captured)
};
let _: Option<()> = x.field.map(|value| do_nothing(value + captured));
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x.field.map(|value| x.do_option_nothing(value + captured));
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x.field.map(|value| {
x.do_option_plus_one(value + captured);
});
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x.field.map(|value| do_nothing(value + captured));
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x.field.map(|value| do_nothing(value + captured));
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x.field.map(|value| {
do_nothing(value + captured);
});
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x.field.map(|value| {
do_nothing(value + captured);
});
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x.field.map(|value| diverge(value + captured));
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x.field.map(|value| diverge(value + captured));
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x.field.map(|value| {
diverge(value + captured);
});
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x.field.map(|value| {
diverge(value + captured);
});
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x.field.map(|value| plus_one(value + captured));
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x.field.map(|value| plus_one(value + captured));
x.field.map(|value| {
let y = plus_one(value + captured);
});
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x.field.map(|value| {
plus_one(value + captured);
});
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x.field.map(|value| {
plus_one(value + captured);
});
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x.field.map(|ref value| do_nothing(value + captured));
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x.field.map(|value| {
do_nothing(value);
do_nothing(value)
});
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x.field.map(|value| {
if value > 0 {
do_nothing(value);
do_nothing(value)
}
});
// Suggestion for the let block should be `{ ... }` as it's too difficult to build a
// proper suggestion for these cases
x.field.map(|value| {
do_nothing(value);
do_nothing(value)
});
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x.field.map(|value| {
do_nothing(value);
do_nothing(value);
});
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// The following should suggest `if let Some(_X) ...` as it's difficult to generate a proper let
// variable name for them
Some(42).map(diverge);
"12".parse::<i32>().ok().map(diverge);
Some(plus_one(1)).map(do_nothing);
// Should suggest `if let Some(_y) ...` to not override the existing foo variable
let y = Some(42);
y.map(do_nothing);
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}
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fn main() {}