Lint usage of `*&` and `*&mut`

fixes #1316
This commit is contained in:
Phil Turnbull 2016-11-22 13:22:37 -05:00
parent 530083c3b9
commit a9f5b90f0f
6 changed files with 129 additions and 1 deletions

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@ -248,6 +248,7 @@ All notable changes to this project will be documented in this file.
[`crosspointer_transmute`]: https://github.com/Manishearth/rust-clippy/wiki#crosspointer_transmute
[`cyclomatic_complexity`]: https://github.com/Manishearth/rust-clippy/wiki#cyclomatic_complexity
[`deprecated_semver`]: https://github.com/Manishearth/rust-clippy/wiki#deprecated_semver
[`deref_addrof`]: https://github.com/Manishearth/rust-clippy/wiki#deref_addrof
[`derive_hash_xor_eq`]: https://github.com/Manishearth/rust-clippy/wiki#derive_hash_xor_eq
[`diverging_sub_expression`]: https://github.com/Manishearth/rust-clippy/wiki#diverging_sub_expression
[`doc_markdown`]: https://github.com/Manishearth/rust-clippy/wiki#doc_markdown

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@ -182,7 +182,7 @@ You can check out this great service at [clippy.bashy.io](https://clippy.bashy.i
## Lints
There are 178 lints included in this crate:
There are 179 lints included in this crate:
name | default | triggers on
-----------------------------------------------------------------------------------------------------------------------|---------|----------------------------------------------------------------------------------------------------------------------------------
@ -214,6 +214,7 @@ name
[crosspointer_transmute](https://github.com/Manishearth/rust-clippy/wiki#crosspointer_transmute) | warn | transmutes that have to or from types that are a pointer to the other
[cyclomatic_complexity](https://github.com/Manishearth/rust-clippy/wiki#cyclomatic_complexity) | warn | functions that should be split up into multiple functions
[deprecated_semver](https://github.com/Manishearth/rust-clippy/wiki#deprecated_semver) | warn | use of `#[deprecated(since = "x")]` where x is not semver
[deref_addrof](https://github.com/Manishearth/rust-clippy/wiki#deref_addrof) | warn | use of `*&` or `*&mut` in an expression
[derive_hash_xor_eq](https://github.com/Manishearth/rust-clippy/wiki#derive_hash_xor_eq) | warn | deriving `Hash` but implementing `PartialEq` explicitly
[diverging_sub_expression](https://github.com/Manishearth/rust-clippy/wiki#diverging_sub_expression) | warn | whether an expression contains a diverging sub expression
[doc_markdown](https://github.com/Manishearth/rust-clippy/wiki#doc_markdown) | warn | presence of `_`, `::` or camel-case outside backticks in documentation

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@ -115,6 +115,7 @@ pub mod precedence;
pub mod print;
pub mod ptr;
pub mod ranges;
pub mod reference;
pub mod regex;
pub mod returns;
pub mod serde;
@ -266,6 +267,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
reg.register_late_lint_pass(box ok_if_let::Pass);
reg.register_late_lint_pass(box if_let_redundant_pattern_matching::Pass);
reg.register_late_lint_pass(box partialeq_ne_impl::Pass);
reg.register_late_lint_pass(box reference::Pass);
reg.register_lint_group("clippy_restrictions", vec![
arithmetic::FLOAT_ARITHMETIC,
@ -431,6 +433,7 @@ pub fn register_plugins(reg: &mut rustc_plugin::Registry) {
ptr::PTR_ARG,
ranges::RANGE_STEP_BY_ZERO,
ranges::RANGE_ZIP_WITH_LEN,
reference::DEREF_ADDROF,
regex::INVALID_REGEX,
regex::REGEX_MACRO,
regex::TRIVIAL_REGEX,

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@ -0,0 +1,48 @@
use rustc::hir::*;
use rustc::lint::*;
use utils::{span_lint_and_then, snippet};
/// **What it does:** Checks for usage of `*&` and `*&mut` in expressions.
///
/// **Why is this bad?** Immediately dereferencing a reference is no-op and
/// makes the code less clear.
///
/// **Known problems:** Multiple dereference/addrof pairs are not handled so
/// the suggested fix for `x = **&&y` is `x = *&y`, which is still incorrect.
///
/// **Example:**
/// ```rust
/// let a = f(*&mut b);
/// let c = *&d;
/// ```
declare_lint! {
pub DEREF_ADDROF,
Warn,
"use of `*&` or `*&mut` in an expression"
}
pub struct Pass;
impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(DEREF_ADDROF)
}
}
impl LateLintPass for Pass {
fn check_expr(&mut self, cx: &LateContext, e: &Expr) {
if let ExprUnary(UnDeref, ref deref_target) = e.node {
if let ExprAddrOf(_, ref addrof_target) = deref_target.node {
span_lint_and_then(
cx,
DEREF_ADDROF,
e.span,
"immediately dereferencing a reference",
|db| {
db.span_suggestion(e.span, "try this",
format!("{}", snippet(cx, addrof_target.span, "_")));
});
}
}
}
}

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@ -4,6 +4,7 @@
#![deny(no_effect, unnecessary_operation)]
#![allow(dead_code)]
#![allow(path_statements)]
#![allow(deref_addrof)]
#![feature(untagged_unions)]
struct Unit;

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@ -0,0 +1,74 @@
#![feature(plugin)]
#![plugin(clippy)]
fn get_number() -> usize {
10
}
fn get_reference(n : &usize) -> &usize {
n
}
#[allow(many_single_char_names)]
#[allow(unused_variables)]
#[deny(deref_addrof)]
fn main() {
let a = 10;
let aref = &a;
let b = *&a;
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION a
let b = *&get_number();
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION get_number()
let b = *get_reference(&a);
let bytes : Vec<usize> = vec![1, 2, 3, 4];
let b = *&bytes[1..2][0];
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION bytes[1..2][0]
let b = *(&a);
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION a
let b = *&&a;
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION &a
let b = **&aref;
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION aref
//This produces a suggestion of 'let b = *&a;' which is still incorrect
let b = **&&a;
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION a
{
let mut x = 10;
let y = *&mut x;
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION x
}
{
//This produces a suggestion of 'let y = *&mut x' which is still incorrect
let mut x = 10;
let y = **&mut &mut x;
//~^ERROR immediately dereferencing a reference
//~|HELP try this
//~|SUGGESTION x
}
}