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Auto merge of #9214 - Jarcho:assign_op_prim, r=Manishearth

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Check `assign_op_pattern` for conflicting borrows

fixes #9180

changelog: [`assign_op_pattern`](https://rust-lang.github.io/rust-clippy/master/#assign_op_pattern): Don't lint when the suggestion would cause borrowck errors.
This commit is contained in:
bors 2022-07-21 17:00:40 +00:00
commit 05a51e5730
4 changed files with 124 additions and 10 deletions
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80
clippy_lints/src/operators/assign_op_pattern.rs
View File

@ -8,6 +8,10 @@
use rustc_hir as hir;
use rustc_hir::intravisit::{walk_expr, Visitor};
use rustc_lint::LateContext;
use rustc_middle::mir::FakeReadCause;
use rustc_middle::ty::BorrowKind;
use rustc_trait_selection::infer::TyCtxtInferExt;
use rustc_typeck::expr_use_visitor::{Delegate, ExprUseVisitor, PlaceBase, PlaceWithHirId};
use super::ASSIGN_OP_PATTERN;
@ -29,6 +33,16 @@ pub(super) fn check<'tcx>(
.map_or(true, |t| t.path.res.def_id() != trait_id);
if implements_trait(cx, ty, trait_id, &[rty.into()]);
then {
// Primitive types execute assign-ops right-to-left. Every other type is left-to-right.
if !(ty.is_primitive() && rty.is_primitive()) {
// TODO: This will have false negatives as it doesn't check if the borrows are
// actually live at the end of their respective expressions.
let mut_borrows = mut_borrows_in_expr(cx, assignee);
let imm_borrows = imm_borrows_in_expr(cx, rhs);
if mut_borrows.iter().any(|id| imm_borrows.contains(id)) {
return;
}
}
span_lint_and_then(
cx,
ASSIGN_OP_PATTERN,
@ -99,3 +113,69 @@ fn visit_expr(&mut self, expr: &'tcx hir::Expr<'_>) {
walk_expr(self, expr);
}
}
fn imm_borrows_in_expr(cx: &LateContext<'_>, e: &hir::Expr<'_>) -> hir::HirIdSet {
struct S(hir::HirIdSet);
impl Delegate<'_> for S {
fn borrow(&mut self, place: &PlaceWithHirId<'_>, _: hir::HirId, kind: BorrowKind) {
if matches!(kind, BorrowKind::ImmBorrow | BorrowKind::UniqueImmBorrow) {
self.0.insert(match place.place.base {
PlaceBase::Local(id) => id,
PlaceBase::Upvar(id) => id.var_path.hir_id,
_ => return,
});
}
}
fn consume(&mut self, _: &PlaceWithHirId<'_>, _: hir::HirId) {}
fn mutate(&mut self, _: &PlaceWithHirId<'_>, _: hir::HirId) {}
fn fake_read(&mut self, _: &PlaceWithHirId<'_>, _: FakeReadCause, _: hir::HirId) {}
fn copy(&mut self, _: &PlaceWithHirId<'_>, _: hir::HirId) {}
}
let mut s = S(hir::HirIdSet::default());
cx.tcx.infer_ctxt().enter(|infcx| {
let mut v = ExprUseVisitor::new(
&mut s,
&infcx,
cx.tcx.hir().body_owner_def_id(cx.enclosing_body.unwrap()),
cx.param_env,
cx.typeck_results(),
);
v.consume_expr(e);
});
s.0
}
fn mut_borrows_in_expr(cx: &LateContext<'_>, e: &hir::Expr<'_>) -> hir::HirIdSet {
struct S(hir::HirIdSet);
impl Delegate<'_> for S {
fn borrow(&mut self, place: &PlaceWithHirId<'_>, _: hir::HirId, kind: BorrowKind) {
if matches!(kind, BorrowKind::MutBorrow) {
self.0.insert(match place.place.base {
PlaceBase::Local(id) => id,
PlaceBase::Upvar(id) => id.var_path.hir_id,
_ => return,
});
}
}
fn consume(&mut self, _: &PlaceWithHirId<'_>, _: hir::HirId) {}
fn mutate(&mut self, _: &PlaceWithHirId<'_>, _: hir::HirId) {}
fn fake_read(&mut self, _: &PlaceWithHirId<'_>, _: FakeReadCause, _: hir::HirId) {}
fn copy(&mut self, _: &PlaceWithHirId<'_>, _: hir::HirId) {}
}
let mut s = S(hir::HirIdSet::default());
cx.tcx.infer_ctxt().enter(|infcx| {
let mut v = ExprUseVisitor::new(
&mut s,
&infcx,
cx.tcx.hir().body_owner_def_id(cx.enclosing_body.unwrap()),
cx.param_env,
cx.typeck_results(),
);
v.consume_expr(e);
});
s.0
}

11
tests/ui/assign_ops.fixed
View File

@ -1,5 +1,7 @@
// run-rustfix
use core::num::Wrapping;
#[allow(dead_code, unused_assignments)]
#[warn(clippy::assign_op_pattern)]
fn main() {
@ -18,4 +20,13 @@ fn main() {
a = 6 << a;
let mut s = String::new();
s += "bla";
// Issue #9180
let mut a = Wrapping(0u32);
a += Wrapping(1u32);
let mut v = vec![0u32, 1u32];
v[0] += v[1];
let mut v = vec![Wrapping(0u32), Wrapping(1u32)];
v[0] = v[0] + v[1];
let _ = || v[0] = v[0] + v[1];
}

11
tests/ui/assign_ops.rs
View File

@ -1,5 +1,7 @@
// run-rustfix
use core::num::Wrapping;
#[allow(dead_code, unused_assignments)]
#[warn(clippy::assign_op_pattern)]
fn main() {
@ -18,4 +20,13 @@ fn main() {
a = 6 << a;
let mut s = String::new();
s = s + "bla";
// Issue #9180
let mut a = Wrapping(0u32);
a = a + Wrapping(1u32);
let mut v = vec![0u32, 1u32];
v[0] = v[0] + v[1];
let mut v = vec![Wrapping(0u32), Wrapping(1u32)];
v[0] = v[0] + v[1];
let _ = || v[0] = v[0] + v[1];
}

32
tests/ui/assign_ops.stderr
View File

@ -1,5 +1,5 @@
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:7:5
--> $DIR/assign_ops.rs:9:5
|
LL | a = a + 1;
| ^^^^^^^^^ help: replace it with: `a += 1`
@ -7,52 +7,64 @@ LL | a = a + 1;
= note: `-D clippy::assign-op-pattern` implied by `-D warnings`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:8:5
--> $DIR/assign_ops.rs:10:5
|
LL | a = 1 + a;
| ^^^^^^^^^ help: replace it with: `a += 1`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:9:5
--> $DIR/assign_ops.rs:11:5
|
LL | a = a - 1;
| ^^^^^^^^^ help: replace it with: `a -= 1`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:10:5
--> $DIR/assign_ops.rs:12:5
|
LL | a = a * 99;
| ^^^^^^^^^^ help: replace it with: `a *= 99`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:11:5
--> $DIR/assign_ops.rs:13:5
|
LL | a = 42 * a;
| ^^^^^^^^^^ help: replace it with: `a *= 42`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:12:5
--> $DIR/assign_ops.rs:14:5
|
LL | a = a / 2;
| ^^^^^^^^^ help: replace it with: `a /= 2`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:13:5
--> $DIR/assign_ops.rs:15:5
|
LL | a = a % 5;
| ^^^^^^^^^ help: replace it with: `a %= 5`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:14:5
--> $DIR/assign_ops.rs:16:5
|
LL | a = a & 1;
| ^^^^^^^^^ help: replace it with: `a &= 1`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:20:5
--> $DIR/assign_ops.rs:22:5
|
LL | s = s + "bla";
| ^^^^^^^^^^^^^ help: replace it with: `s += "bla"`
error: aborting due to 9 previous errors
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:26:5
|
LL | a = a + Wrapping(1u32);
| ^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `a += Wrapping(1u32)`
error: manual implementation of an assign operation
--> $DIR/assign_ops.rs:28:5
|
LL | v[0] = v[0] + v[1];
| ^^^^^^^^^^^^^^^^^^ help: replace it with: `v[0] += v[1]`
error: aborting due to 11 previous errors