New lint: mut_mut (closes issue #9)
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@ -22,6 +22,7 @@ Lints included in this crate:
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- `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)`
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- `redundant_closure`: Warns on usage of eta-reducible closures like `|a| foo(a)` (which can be written as just `foo`)
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- `identity_op`: Warns on identity operations like `x + 0` or `y / 1` (which can be reduced to `x` and `y`, respectively)
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- `mut_mut`: Warns on `&mut &mut` which is either a copy'n'paste error, or shows a fundamental misunderstanding of references
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To use, add the following lines to your Cargo.toml:
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@ -23,6 +23,7 @@ pub mod needless_bool;
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pub mod approx_const;
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pub mod eta_reduction;
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pub mod identity_op;
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pub mod mut_mut;
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#[plugin_registrar]
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pub fn plugin_registrar(reg: &mut Registry) {
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@ -40,6 +41,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
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reg.register_lint_pass(box misc::Precedence as LintPassObject);
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reg.register_lint_pass(box eta_reduction::EtaPass as LintPassObject);
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reg.register_lint_pass(box identity_op::IdentityOp as LintPassObject);
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reg.register_lint_pass(box mut_mut::MutMut as LintPassObject);
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reg.register_lint_group("clippy", vec![types::BOX_VEC, types::LINKEDLIST,
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misc::SINGLE_MATCH, misc::STR_TO_STRING,
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@ -53,5 +55,6 @@ pub fn plugin_registrar(reg: &mut Registry) {
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misc::PRECEDENCE,
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eta_reduction::REDUNDANT_CLOSURE,
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identity_op::IDENTITY_OP,
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mut_mut::MUT_MUT,
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]);
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}
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51
src/mut_mut.rs
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51
src/mut_mut.rs
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@ -0,0 +1,51 @@
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use syntax::ptr::P;
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use syntax::ast;
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use syntax::ast::*;
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use syntax::ast_util::{is_comparison_binop, binop_to_string};
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use syntax::visit::{FnKind};
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use rustc::lint::{Context, LintPass, LintArray, Lint, Level};
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use rustc::middle::ty::{self, expr_ty, ty_str, ty_ptr, ty_rptr, ty_float};
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use syntax::codemap::{Span, Spanned};
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declare_lint!(pub MUT_MUT, Warn,
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"Warn on usage of double-mut refs, e.g. '&mut &mut ...'");
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#[derive(Copy,Clone)]
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pub struct MutMut;
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impl LintPass for MutMut {
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fn get_lints(&self) -> LintArray {
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lint_array!(MUT_MUT)
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}
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fn check_expr(&mut self, cx: &Context, expr: &Expr) {
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fn unwrap_addr(expr : &Expr) -> Option<&Expr> {
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match expr.node {
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ExprAddrOf(MutMutable, ref e) => Option::Some(e),
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_ => Option::None
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}
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}
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if unwrap_addr(expr).and_then(unwrap_addr).is_some() {
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cx.span_lint(MUT_MUT, expr.span,
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"We're not sure what this means, so if you know, please tell us.")
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}
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}
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fn check_ty(&mut self, cx: &Context, ty: &Ty) {
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fn unwrap_mut(ty : &Ty) -> Option<&Ty> {
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match ty.node {
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TyPtr(MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),
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TyRptr(_, MutTy{ ty: ref pty, mutbl: MutMutable }) => Option::Some(pty),
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_ => Option::None
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}
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}
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if unwrap_mut(ty).and_then(unwrap_mut).is_some() {
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cx.span_lint(MUT_MUT, ty.span,
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"We're not sure what this means, so if you know, please tell us.")
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}
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}
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}
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20
tests/compile-fail/mut_mut.rs
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20
tests/compile-fail/mut_mut.rs
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@ -0,0 +1,20 @@
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#![feature(plugin)]
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#![plugin(clippy)]
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#[deny(mut_mut)]
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fn fun(x : &mut &mut u32) -> bool { //~ERROR
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**x > 0
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}
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#[deny(mut_mut)]
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fn main() {
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let mut x = &mut &mut 1u32; //~ERROR
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if fun(x) {
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let y : &mut &mut &mut u32 = &mut &mut &mut 2;
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//~^ ERROR
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//~^^ ERROR
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//~^^^ ERROR
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//~^^^^ ERROR
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***y + **x;
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}
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}
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