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Improve invalid_reference_casting lint

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This commit is contained in:
Urgau 2023-08-13 17:08:33 +02:00
parent 6933848fbf
commit 91b05f8e09
3 changed files with 133 additions and 35 deletions
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49
compiler/rustc_lint/src/reference_casting.rs
View File

@ -100,7 +100,7 @@ fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>)
fn from_casts<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>) -> Option<&'tcx Expr<'tcx>> {
// <expr> as *mut ...
let e = if let ExprKind::Cast(e, t) = e.kind
let mut e = if let ExprKind::Cast(e, t) = e.kind
&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Mut, .. }) = cx.typeck_results().node_type(t.hir_id).kind() {
e
// <expr>.cast_mut()
@ -112,23 +112,36 @@ fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>)
return None;
};
let e = e.peel_blocks();
// <expr> as *const ...
let e = if let ExprKind::Cast(e, t) = e.kind
&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Not, .. }) = cx.typeck_results().node_type(t.hir_id).kind() {
e
// ptr::from_ref(<expr>)
} else if let ExprKind::Call(path, [arg]) = e.kind
&& let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& cx.tcx.is_diagnostic_item(sym::ptr_from_ref, def_id) {
arg
} else {
return None;
};
Some(e)
let mut had_at_least_one_cast = false;
loop {
e = e.peel_blocks();
// <expr> as *mut/const ... or <expr> as <uint>
e = if let ExprKind::Cast(expr, t) = e.kind
&& matches!(cx.typeck_results().node_type(t.hir_id).kind(), ty::RawPtr(_) | ty::Uint(_)) {
had_at_least_one_cast = true;
expr
// <expr>.cast(), <expr>.cast_mut() or <expr>.cast_const()
} else if let ExprKind::MethodCall(_, expr, [], _) = e.kind
&& let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_cast | sym::const_ptr_cast | sym::ptr_cast_mut | sym::ptr_cast_const)
)
{
had_at_least_one_cast = true;
expr
// ptr::from_ref(<expr>)
} else if let ExprKind::Call(path, [arg]) = e.kind
&& let ExprKind::Path(ref qpath) = path.kind
&& let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
&& cx.tcx.is_diagnostic_item(sym::ptr_from_ref, def_id) {
return Some(arg);
} else if had_at_least_one_cast {
return Some(e);
} else {
return None;
};
}
}
fn from_transmute<'tcx>(

29
tests/ui/lint/reference_casting.rs
View File

@ -9,6 +9,10 @@ extern "C" {
fn int_ffi(c: *mut i32);
}
fn static_u8() -> &'static u8 {
&8
}
unsafe fn ref_to_mut() {
let num = &3i32;
@ -24,12 +28,28 @@ unsafe fn ref_to_mut() {
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(std::ptr::from_ref({ num }) as *mut i32);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(num as *const i32).cast::<i32>().cast_mut();
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(num as *const i32).cast::<i32>().cast_mut().cast_const().cast_mut();
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(std::ptr::from_ref(static_u8()) as *mut i32);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *std::mem::transmute::<_, *mut i32>(num);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let deferred = num as *const i32 as *mut i32;
let _num = &mut *deferred;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let deferred = (std::ptr::from_ref(num) as *const i32 as *const i32).cast_mut() as *mut i32;
let _num = &mut *deferred;
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *(num as *const _ as usize as *mut i32);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
unsafe fn generic_ref_cast_mut<T>(this: &T) -> &mut T {
&mut *((this as *const _) as *mut _)
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
}
}
unsafe fn assign_to_ref() {
@ -55,6 +75,15 @@ unsafe fn assign_to_ref() {
let value = num as *const i32 as *mut i32;
*value = 1;
//~^ ERROR assigning to `&T` is undefined behavior
*(num as *const i32).cast::<i32>().cast_mut() = 2;
//~^ ERROR assigning to `&T` is undefined behavior
*(num as *const _ as usize as *mut i32) = 2;
//~^ ERROR assigning to `&T` is undefined behavior
unsafe fn generic_assign_to_ref<T>(this: &T, a: T) {
*(this as *const _ as *mut _) = a;
//~^ ERROR assigning to `&T` is undefined behavior
}
}
unsafe fn no_warn() {

90
tests/ui/lint/reference_casting.stderr
View File

@ -1,5 +1,5 @@
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:15:16
--> $DIR/reference_casting.rs:19:16
|
LL | let _num = &mut *(num as *const i32 as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -7,98 +7,154 @@ LL | let _num = &mut *(num as *const i32 as *mut i32);
= note: `#[deny(invalid_reference_casting)]` on by default
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:17:16
--> $DIR/reference_casting.rs:21:16
|
LL | let _num = &mut *(num as *const i32).cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:19:16
--> $DIR/reference_casting.rs:23:16
|
LL | let _num = &mut *std::ptr::from_ref(num).cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:21:16
--> $DIR/reference_casting.rs:25:16
|
LL | let _num = &mut *std::ptr::from_ref({ num }).cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:23:16
--> $DIR/reference_casting.rs:27:16
|
LL | let _num = &mut *{ std::ptr::from_ref(num) }.cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:25:16
--> $DIR/reference_casting.rs:29:16
|
LL | let _num = &mut *(std::ptr::from_ref({ num }) as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:27:16
--> $DIR/reference_casting.rs:31:16
|
LL | let _num = &mut *(num as *const i32).cast::<i32>().cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:33:16
|
LL | let _num = &mut *(num as *const i32).cast::<i32>().cast_mut().cast_const().cast_mut();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:35:16
|
LL | let _num = &mut *(std::ptr::from_ref(static_u8()) as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:37:16
|
LL | let _num = &mut *std::mem::transmute::<_, *mut i32>(num);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:31:16
--> $DIR/reference_casting.rs:41:16
|
LL | let deferred = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
LL | let _num = &mut *deferred;
| ^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:44:16
|
LL | let deferred = (std::ptr::from_ref(num) as *const i32 as *const i32).cast_mut() as *mut i32;
| ---------------------------------------------------------------------------- casting happend here
LL | let _num = &mut *deferred;
| ^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:46:16
|
LL | let _num = &mut *(num as *const _ as usize as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:50:9
|
LL | &mut *((this as *const _) as *mut _)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:40:5
--> $DIR/reference_casting.rs:60:5
|
LL | *(a as *const _ as *mut _) = String::from("Replaced");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:42:5
--> $DIR/reference_casting.rs:62:5
|
LL | *(a as *const _ as *mut String) += " world";
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:44:5
--> $DIR/reference_casting.rs:64:5
|
LL | *std::ptr::from_ref(num).cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:46:5
--> $DIR/reference_casting.rs:66:5
|
LL | *std::ptr::from_ref({ num }).cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:48:5
--> $DIR/reference_casting.rs:68:5
|
LL | *{ std::ptr::from_ref(num) }.cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:50:5
--> $DIR/reference_casting.rs:70:5
|
LL | *(std::ptr::from_ref({ num }) as *mut i32) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:52:5
--> $DIR/reference_casting.rs:72:5
|
LL | *std::mem::transmute::<_, *mut i32>(num) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:56:5
--> $DIR/reference_casting.rs:76:5
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
LL | *value = 1;
| ^^^^^^^^^^
error: aborting due to 16 previous errors
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:78:5
|
LL | *(num as *const i32).cast::<i32>().cast_mut() = 2;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:80:5
|
LL | *(num as *const _ as usize as *mut i32) = 2;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:84:9
|
LL | *(this as *const _ as *mut _) = a;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 25 previous errors