New lint: mut_mut (closes issue #9)

This commit is contained in:
llogiq 2015-05-18 09:02:24 +02:00
parent cd62ef3450
commit 96bfade4f1
4 changed files with 75 additions and 0 deletions

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@ -22,6 +22,7 @@ Lints included in this crate:
- `precedence`: Warns on expressions where precedence may trip up the unwary reader of the source and suggests adding parenthesis, e.g. `x << 2 + y` will be parsed as `x << (2 + y)`
- `redundant_closure`: Warns on usage of eta-reducible closures like `|a| foo(a)` (which can be written as just `foo`)
- `identity_op`: Warns on identity operations like `x + 0` or `y / 1` (which can be reduced to `x` and `y`, respectively)
- `mut_mut`: Warns on `&mut &mut` which is either a copy'n'paste error, or shows a fundamental misunderstanding of references
To use, add the following lines to your Cargo.toml:

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@ -23,6 +23,7 @@ pub mod needless_bool;
pub mod approx_const;
pub mod eta_reduction;
pub mod identity_op;
pub mod mut_mut;
#[plugin_registrar]
pub fn plugin_registrar(reg: &mut Registry) {
@ -40,6 +41,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
reg.register_lint_pass(box misc::Precedence as LintPassObject);
reg.register_lint_pass(box eta_reduction::EtaPass as LintPassObject);
reg.register_lint_pass(box identity_op::IdentityOp as LintPassObject);
reg.register_lint_pass(box mut_mut::MutMut as LintPassObject);
reg.register_lint_group("clippy", vec![types::BOX_VEC, types::LINKEDLIST,
misc::SINGLE_MATCH, misc::STR_TO_STRING,
@ -53,5 +55,6 @@ pub fn plugin_registrar(reg: &mut Registry) {
misc::PRECEDENCE,
eta_reduction::REDUNDANT_CLOSURE,
identity_op::IDENTITY_OP,
mut_mut::MUT_MUT,
]);
}

51
src/mut_mut.rs Normal file
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@ -0,0 +1,51 @@
use syntax::ptr::P;
use syntax::ast;
use syntax::ast::*;
use syntax::ast_util::{is_comparison_binop, binop_to_string};
use syntax::visit::{FnKind};
use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
use rustc::middle::ty::{self, expr_ty, ty_str, ty_ptr, ty_rptr, ty_float};
use syntax::codemap::{Span, Spanned};
declare_lint!(pub MUT_MUT, Warn,
"Warn on usage of double-mut refs, e.g. '&mut &mut ...'");
#[derive(Copy,Clone)]
pub struct MutMut;
impl LintPass for MutMut {
fn get_lints(&self) -> LintArray {
lint_array!(MUT_MUT)
}
fn check_expr(&mut self, cx: &Context, expr: &Expr) {
fn unwrap_addr(expr : &Expr) -> Option<&Expr> {
match expr.node {
ExprAddrOf(MutMutable, ref e) => Option::Some(e),
_ => Option::None
}
}
if unwrap_addr(expr).and_then(unwrap_addr).is_some() {
cx.span_lint(MUT_MUT, expr.span,
"We're not sure what this means, so if you know, please tell us.")
}
}
fn check_ty(&mut self, cx: &Context, ty: &Ty) {
fn unwrap_mut(ty : &Ty) -> Option<&Ty> {
match ty.node {
TyPtr(MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),
TyRptr(_, MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),
_ => Option::None
}
}
if unwrap_mut(ty).and_then(unwrap_mut).is_some() {
cx.span_lint(MUT_MUT, ty.span,
"We're not sure what this means, so if you know, please tell us.")
}
}
}

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@ -0,0 +1,20 @@
#![feature(plugin)]
#![plugin(clippy)]
#[deny(mut_mut)]
fn fun(x : &mut &mut u32) -> bool { //~ERROR
**x > 0
}
#[deny(mut_mut)]
fn main() {
let mut x = &mut &mut 1u32; //~ERROR
if fun(x) {
let y : &mut &mut &mut u32 = &mut &mut &mut 2;
//~^ ERROR
//~^^ ERROR
//~^^^ ERROR
//~^^^^ ERROR
***y + **x;
}
}