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Fix op_ref in case of nonexisting operations

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This commit is contained in:
Oliver Schneider 2017-04-10 15:10:19 +02:00
parent 0432f1efd3
commit b76ce176bb
3 changed files with 112 additions and 44 deletions
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122
clippy_lints/src/eq_op.rs
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@ -1,6 +1,6 @@
use rustc::hir::*;
use rustc::lint::*;
use utils::{SpanlessEq, span_lint, span_lint_and_then, multispan_sugg, snippet};
use utils::{SpanlessEq, span_lint, span_lint_and_then, multispan_sugg, snippet, implements_trait};
use utils::sugg::Sugg;
/// **What it does:** Checks for equal operands to comparison, logical and
@ -60,53 +60,87 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for EqOp {
e.span,
&format!("equal expressions as operands to `{}`", op.node.as_str()));
} else {
match (&left.node, &right.node) {
(&ExprAddrOf(_, ref l), &ExprAddrOf(_, ref r)) => {
span_lint_and_then(cx,
OP_REF,
e.span,
"taken reference of both operands, which is done automatically by the operator anyway",
|db| {
let lsnip = snippet(cx, l.span, "...").to_string();
let rsnip = snippet(cx, r.span, "...").to_string();
multispan_sugg(db,
"use the values directly".to_string(),
vec![(left.span, lsnip),
(right.span, rsnip)]);
let trait_id = match op.node {
BiAdd => cx.tcx.lang_items.add_trait(),
BiSub => cx.tcx.lang_items.sub_trait(),
BiMul => cx.tcx.lang_items.mul_trait(),
BiDiv => cx.tcx.lang_items.div_trait(),
BiRem => cx.tcx.lang_items.rem_trait(),
BiAnd => None,
BiOr => None,
BiBitXor => cx.tcx.lang_items.bitxor_trait(),
BiBitAnd => cx.tcx.lang_items.bitand_trait(),
BiBitOr => cx.tcx.lang_items.bitor_trait(),
BiShl => cx.tcx.lang_items.shl_trait(),
BiShr => cx.tcx.lang_items.shr_trait(),
BiNe |
BiEq => cx.tcx.lang_items.eq_trait(),
BiLt |
BiLe |
BiGe |
BiGt => cx.tcx.lang_items.ord_trait(),
};
if let Some(trait_id) = trait_id {
match (&left.node, &right.node) {
// do not suggest to dereference literals
(&ExprLit(..), _) |
(_, &ExprLit(..)) => {},
// &foo == &bar
(&ExprAddrOf(_, ref l), &ExprAddrOf(_, ref r)) => {
if implements_trait(cx, cx.tables.expr_ty(l), trait_id, &[cx.tables.expr_ty(r)], None) {
span_lint_and_then(cx,
OP_REF,
e.span,
"taken reference of both operands, which is done automatically by the operator anyway",
|db| {
let lsnip = snippet(cx, l.span, "...").to_string();
let rsnip = snippet(cx, r.span, "...").to_string();
multispan_sugg(db,
"use the values directly".to_string(),
vec![(left.span, lsnip),
(right.span, rsnip)]);
}
)
}
)
}
(&ExprAddrOf(_, ref l), _) => {
span_lint_and_then(cx,
OP_REF,
e.span,
"taken reference of left operand",
|db| {
let lsnip = snippet(cx, l.span, "...").to_string();
let rsnip = Sugg::hir(cx, right, "...").deref().to_string();
multispan_sugg(db,
"dereference the right operand instead".to_string(),
vec![(left.span, lsnip),
(right.span, rsnip)]);
}
// &foo == bar
(&ExprAddrOf(_, ref l), _) => {
if implements_trait(cx, cx.tables.expr_ty(l), trait_id, &[cx.tables.expr_ty(right)], None) {
span_lint_and_then(cx,
OP_REF,
e.span,
"taken reference of left operand",
|db| {
let lsnip = snippet(cx, l.span, "...").to_string();
let rsnip = Sugg::hir(cx, right, "...").deref().to_string();
multispan_sugg(db,
"dereference the right operand instead".to_string(),
vec![(left.span, lsnip),
(right.span, rsnip)]);
}
)
}
)
}
(_, &ExprAddrOf(_, ref r)) => {
span_lint_and_then(cx,
OP_REF,
e.span,
"taken reference of right operand",
|db| {
let lsnip = Sugg::hir(cx, left, "...").deref().to_string();
let rsnip = snippet(cx, r.span, "...").to_string();
multispan_sugg(db,
"dereference the left operand instead".to_string(),
vec![(left.span, lsnip),
(right.span, rsnip)]);
}
// foo == &bar
(_, &ExprAddrOf(_, ref r)) => {
if implements_trait(cx, cx.tables.expr_ty(left), trait_id, &[cx.tables.expr_ty(r)], None) {
span_lint_and_then(cx,
OP_REF,
e.span,
"taken reference of right operand",
|db| {
let lsnip = Sugg::hir(cx, left, "...").deref().to_string();
let rsnip = snippet(cx, r.span, "...").to_string();
multispan_sugg(db,
"dereference the left operand instead".to_string(),
vec![(left.span, lsnip),
(right.span, rsnip)]);
}
)
}
)
}
_ => {}
}
_ => {}
}
}
}

24
tests/ui/op_ref.rs Normal file
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@ -0,0 +1,24 @@
#![feature(plugin)]
#![plugin(clippy)]
#![allow(unused_variables, blacklisted_name)]
use std::collections::HashSet;
fn main() {
let tracked_fds: HashSet<i32> = HashSet::new();
let new_fds = HashSet::new();
let unwanted = &tracked_fds - &new_fds;
let foo = &5 - &6;
let bar = String::new();
let bar = "foo" == &bar;
let a = "a".to_string();
let b = "a";
if b < &a {
println!("OK");
}
}

10
tests/ui/op_ref.stderr Normal file
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@ -0,0 +1,10 @@
warning: taken reference of both operands, which is done automatically by the operator anyway
--> $DIR/op_ref.rs:13:15
|
13 | let foo = &5 - &6;
| ^^^^^^^
|
= note: #[warn(op_ref)] on by default
help: use the values directly
| let foo = 5 - 6;