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mem_replace_with_uninit: suggest std::ptr::read

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This commit is contained in:
Ericko Samudera 2020-06-08 00:44:14 +07:00
parent 6c833df69b
commit 8c1ee063bb
3 changed files with 71 additions and 36 deletions
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40
clippy_lints/src/mem_replace.rs
View File

@ -135,21 +135,48 @@ fn check_replace_option_with_none(cx: &LateContext<'_, '_>, src: &Expr<'_>, dest
}
}
fn check_replace_with_uninit(cx: &LateContext<'_, '_>, src: &Expr<'_>, expr_span: Span) {
if let ExprKind::Call(ref repl_func, ref repl_args) = src.kind {
fn check_replace_with_uninit(cx: &LateContext<'_, '_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) {
if_chain! {
// check if replacement is mem::MaybeUninit::uninit().assume_init()
if let Some(method_def_id) = cx.tables.type_dependent_def_id(src.hir_id);
if cx.tcx.is_diagnostic_item(sym::assume_init, method_def_id);
then {
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
MEM_REPLACE_WITH_UNINIT,
expr_span,
"replacing with `mem::MaybeUninit::uninit().assume_init()`",
"consider using",
format!(
"std::ptr::read({})",
snippet_with_applicability(cx, dest.span, "", &mut applicability)
),
applicability,
);
return;
}
}
if_chain! {
if let ExprKind::Call(ref repl_func, ref repl_args) = src.kind;
if repl_args.is_empty();
if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
if let Some(repl_def_id) = cx.tables.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
then {
if cx.tcx.is_diagnostic_item(sym::mem_uninitialized, repl_def_id) {
span_lint_and_help(
let mut applicability = Applicability::MachineApplicable;
span_lint_and_sugg(
cx,
MEM_REPLACE_WITH_UNINIT,
expr_span,
"replacing with `mem::uninitialized()`",
None,
"consider using the `take_mut` crate instead",
"consider using",
format!(
"std::ptr::read({})",
snippet_with_applicability(cx, dest.span, "", &mut applicability)
),
applicability,
);
} else if cx.tcx.is_diagnostic_item(sym::mem_zeroed, repl_def_id) &&
!cx.tables.expr_ty(src).is_primitive() {
@ -165,7 +192,6 @@ fn check_replace_with_uninit(cx: &LateContext<'_, '_>, src: &Expr<'_>, expr_span
}
}
}
}
fn check_replace_with_default(cx: &LateContext<'_, '_>, src: &Expr<'_>, dest: &Expr<'_>, expr_span: Span) {
if let ExprKind::Call(ref repl_func, _) = src.kind {
@ -209,7 +235,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MemReplace {
if let [dest, src] = &**func_args;
then {
check_replace_option_with_none(cx, src, dest, expr.span);
check_replace_with_uninit(cx, src, expr.span);
check_replace_with_uninit(cx, src, dest, expr.span);
check_replace_with_default(cx, src, dest, expr.span);
}
}

6
tests/ui/repl_uninit.rs
View File

@ -17,6 +17,12 @@ fn main() {
std::mem::forget(mem::replace(&mut v, new_v));
}
unsafe {
let taken_v = mem::replace(&mut v, mem::MaybeUninit::uninit().assume_init());
let new_v = might_panic(taken_v);
std::mem::forget(mem::replace(&mut v, new_v));
}
unsafe {
let taken_v = mem::replace(&mut v, mem::zeroed());
let new_v = might_panic(taken_v);

19
tests/ui/repl_uninit.stderr
View File

@ -2,13 +2,18 @@ error: replacing with `mem::uninitialized()`
--> $DIR/repl_uninit.rs:15:23
|
LL | let taken_v = mem::replace(&mut v, mem::uninitialized());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::ptr::read(&mut v)`
|
= note: `-D clippy::mem-replace-with-uninit` implied by `-D warnings`
= help: consider using the `take_mut` crate instead
error: replacing with `mem::MaybeUninit::uninit().assume_init()`
--> $DIR/repl_uninit.rs:21:23
|
LL | let taken_v = mem::replace(&mut v, mem::MaybeUninit::uninit().assume_init());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::ptr::read(&mut v)`
error: replacing with `mem::zeroed()`
--> $DIR/repl_uninit.rs:21:23
--> $DIR/repl_uninit.rs:27:23
|
LL | let taken_v = mem::replace(&mut v, mem::zeroed());
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -16,12 +21,10 @@ LL | let taken_v = mem::replace(&mut v, mem::zeroed());
= help: consider using a default value or the `take_mut` crate instead
error: replacing with `mem::uninitialized()`
--> $DIR/repl_uninit.rs:33:28
--> $DIR/repl_uninit.rs:39:28
|
LL | let taken_u = unsafe { mem::replace(uref, mem::uninitialized()) };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider using the `take_mut` crate instead
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::ptr::read(uref)`
error: aborting due to 3 previous errors
error: aborting due to 4 previous errors