mikros/rust
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Simplify casting logic of the invalid_reference_casting lint

Browse Source
This commit is contained in:
Urgau 2023-09-27 15:38:32 +02:00
parent e577dcdd4d
commit bd360472b1
3 changed files with 87 additions and 105 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

112
compiler/rustc_lint/src/reference_casting.rs
View File

@ -104,99 +104,51 @@ fn is_operation_we_care_about<'tcx>(
deref_assign_or_addr_of(e).or_else(|| ptr_write(cx, e))
}
fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'tcx>) -> bool {
let e = e.peel_blocks();
fn is_cast_from_const_to_mut<'tcx>(cx: &LateContext<'tcx>, orig_expr: &'tcx Expr<'tcx>) -> bool {
let mut need_check_freeze = false;
let mut e = orig_expr;
fn from_casts<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'tcx>,
need_check_freeze: &mut bool,
) -> Option<&'tcx Expr<'tcx>> {
// <expr> as *mut ...
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()
let end_ty = cx.typeck_results().node_type(orig_expr.hir_id);
// Bail out early if the end type is **not** a mutable pointer.
if !matches!(end_ty.kind(), ty::RawPtr(TypeAndMut { ty: _, mutbl: Mutability::Mut })) {
return false;
}
loop {
e = e.peel_blocks();
// <expr> as ...
e = if let ExprKind::Cast(expr, _) = e.kind {
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)
&& cx.tcx.is_diagnostic_item(sym::ptr_cast_mut, def_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)
)
{
expr
// UnsafeCell::raw_get(<expr>)
// ptr::from_ref(<expr>), UnsafeCell::raw_get(<expr>) or mem::transmute<_, _>(<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::unsafe_cell_raw_get, def_id)
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_from_ref | sym::unsafe_cell_raw_get | sym::transmute)
)
{
*need_check_freeze = true;
if cx.tcx.is_diagnostic_item(sym::unsafe_cell_raw_get, def_id) {
need_check_freeze = true;
}
arg
} else {
return None;
break;
};
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>) or UnsafeCell::raw_get(<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()
&& matches!(
cx.tcx.get_diagnostic_name(def_id),
Some(sym::ptr_from_ref | sym::unsafe_cell_raw_get)
)
{
if cx.tcx.is_diagnostic_item(sym::unsafe_cell_raw_get, def_id) {
*need_check_freeze = true;
}
return Some(arg);
} else if had_at_least_one_cast {
return Some(e);
} else {
return None;
};
}
}
fn from_transmute<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'tcx>,
) -> Option<&'tcx Expr<'tcx>> {
// mem::transmute::<_, *mut _>(<expr>)
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::transmute, def_id)
&& let ty::RawPtr(TypeAndMut { mutbl: Mutability::Mut, .. }) = cx.typeck_results().node_type(e.hir_id).kind() {
Some(arg)
} else {
None
}
}
let mut need_check_freeze = false;
let Some(e) = from_casts(cx, e, &mut need_check_freeze).or_else(|| from_transmute(cx, e))
else {
return false;
};
let e = e.peel_blocks();
let node_type = cx.typeck_results().node_type(e.hir_id);
if let ty::Ref(_, inner_ty, Mutability::Not) = node_type.kind() {
let start_ty = cx.typeck_results().node_type(e.hir_id);
if let ty::Ref(_, inner_ty, Mutability::Not) = start_ty.kind() {
// If an UnsafeCell method is involved we need to additionaly check the
// inner type for the presence of the Freeze trait (ie does NOT contain
// an UnsafeCell), since in that case we would incorrectly lint on valid casts.

6
tests/ui/lint/reference_casting.rs
View File

@ -36,6 +36,8 @@ unsafe fn ref_to_mut() {
//~^ 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 _num = &mut *(std::mem::transmute::<_, *mut i32>(num) as *mut i32);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
let _num = &mut *std::cell::UnsafeCell::raw_get(
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
num as *const i32 as *const std::cell::UnsafeCell<i32>
@ -52,6 +54,8 @@ unsafe fn ref_to_mut() {
//~^ 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
let _num = &mut *(std::mem::transmute::<_, *mut _>(num as *const i32) as *mut i32);
//~^ ERROR casting `&T` to `&mut T` is undefined behavior
static NUM: &'static i32 = &2;
let num = NUM as *const i32 as *mut i32;
@ -95,6 +99,8 @@ unsafe fn assign_to_ref() {
//~^ ERROR assigning to `&T` is undefined behavior
*std::mem::transmute::<_, *mut i32>(num) += 1;
//~^ ERROR assigning to `&T` is undefined behavior
*(std::mem::transmute::<_, *mut i32>(num) as *mut i32) += 1;
//~^ ERROR assigning to `&T` is undefined behavior
std::ptr::write(
//~^ ERROR assigning to `&T` is undefined behavior
std::mem::transmute::<*const i32, *mut i32>(num),

74
tests/ui/lint/reference_casting.stderr
View File

@ -82,6 +82,14 @@ 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:39:16
|
LL | let _num = &mut *(std::mem::transmute::<_, *mut i32>(num) as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:41:16
|
LL | let _num = &mut *std::cell::UnsafeCell::raw_get(
| ________________^
LL | |
@ -92,7 +100,7 @@ LL | | );
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:45:16
--> $DIR/reference_casting.rs:47:16
|
LL | let deferred = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -102,7 +110,7 @@ LL | let _num = &mut *deferred;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:48:16
--> $DIR/reference_casting.rs:50:16
|
LL | let deferred = (std::ptr::from_ref(num) as *const i32 as *const i32).cast_mut() as *mut i32;
| ---------------------------------------------------------------------------- casting happend here
@ -112,7 +120,7 @@ LL | let _num = &mut *deferred;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:51:16
--> $DIR/reference_casting.rs:53:16
|
LL | let deferred = (std::ptr::from_ref(num) as *const i32 as *const i32).cast_mut() as *mut i32;
| ---------------------------------------------------------------------------- casting happend here
@ -123,7 +131,7 @@ LL | let _num = &mut *deferred_rebind;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:53:16
--> $DIR/reference_casting.rs:55:16
|
LL | let _num = &mut *(num as *const _ as usize as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -131,7 +139,15 @@ LL | let _num = &mut *(num as *const _ as usize as *mut i32);
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:60:16
--> $DIR/reference_casting.rs:57:16
|
LL | let _num = &mut *(std::mem::transmute::<_, *mut _>(num as *const i32) as *mut i32);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:64:16
|
LL | let num = NUM as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -142,7 +158,7 @@ LL | let _num = &mut *num;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:64:9
--> $DIR/reference_casting.rs:68:9
|
LL | &mut *((this as *const _) as *mut _)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -150,7 +166,7 @@ LL | &mut *((this as *const _) as *mut _)
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:69:18
--> $DIR/reference_casting.rs:73:18
|
LL | unsafe { &mut *std::cell::UnsafeCell::raw_get(x as *const _ as *const _) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -158,7 +174,7 @@ LL | unsafe { &mut *std::cell::UnsafeCell::raw_get(x as *const _ as *con
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
--> $DIR/reference_casting.rs:74:18
--> $DIR/reference_casting.rs:78:18
|
LL | unsafe { &mut *std::cell::UnsafeCell::raw_get(x as *const _ as *const _) }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -166,7 +182,7 @@ LL | unsafe { &mut *std::cell::UnsafeCell::raw_get(x as *const _ as *con
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:84:5
--> $DIR/reference_casting.rs:88:5
|
LL | *(a as *const _ as *mut _) = String::from("Replaced");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -174,7 +190,7 @@ LL | *(a as *const _ as *mut _) = String::from("Replaced");
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:86:5
--> $DIR/reference_casting.rs:90:5
|
LL | *(a as *const _ as *mut String) += " world";
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -182,7 +198,7 @@ LL | *(a as *const _ as *mut String) += " world";
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:88:5
--> $DIR/reference_casting.rs:92:5
|
LL | *std::ptr::from_ref(num).cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -190,7 +206,7 @@ LL | *std::ptr::from_ref(num).cast_mut() += 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:90:5
--> $DIR/reference_casting.rs:94:5
|
LL | *std::ptr::from_ref({ num }).cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -198,7 +214,7 @@ LL | *std::ptr::from_ref({ num }).cast_mut() += 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:92:5
--> $DIR/reference_casting.rs:96:5
|
LL | *{ std::ptr::from_ref(num) }.cast_mut() += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -206,7 +222,7 @@ LL | *{ std::ptr::from_ref(num) }.cast_mut() += 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:94:5
--> $DIR/reference_casting.rs:98:5
|
LL | *(std::ptr::from_ref({ num }) as *mut i32) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -214,7 +230,7 @@ LL | *(std::ptr::from_ref({ num }) as *mut i32) += 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:96:5
--> $DIR/reference_casting.rs:100:5
|
LL | *std::mem::transmute::<_, *mut i32>(num) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -222,7 +238,15 @@ LL | *std::mem::transmute::<_, *mut i32>(num) += 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:98:5
--> $DIR/reference_casting.rs:102:5
|
LL | *(std::mem::transmute::<_, *mut i32>(num) as *mut i32) += 1;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:104:5
|
LL | / std::ptr::write(
LL | |
@ -234,7 +258,7 @@ LL | | );
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:105:5
--> $DIR/reference_casting.rs:111:5
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -244,7 +268,7 @@ LL | *value = 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:108:5
--> $DIR/reference_casting.rs:114:5
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -255,7 +279,7 @@ LL | *value_rebind = 1;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:110:5
--> $DIR/reference_casting.rs:116:5
|
LL | *(num as *const i32).cast::<i32>().cast_mut() = 2;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -263,7 +287,7 @@ LL | *(num as *const i32).cast::<i32>().cast_mut() = 2;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:112:5
--> $DIR/reference_casting.rs:118:5
|
LL | *(num as *const _ as usize as *mut i32) = 2;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -271,7 +295,7 @@ LL | *(num as *const _ as usize as *mut i32) = 2;
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:114:5
--> $DIR/reference_casting.rs:120:5
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -282,7 +306,7 @@ LL | std::ptr::write(value, 2);
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:116:5
--> $DIR/reference_casting.rs:122:5
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -293,7 +317,7 @@ LL | std::ptr::write_unaligned(value, 2);
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:118:5
--> $DIR/reference_casting.rs:124:5
|
LL | let value = num as *const i32 as *mut i32;
| ----------------------------- casting happend here
@ -304,12 +328,12 @@ LL | std::ptr::write_volatile(value, 2);
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
--> $DIR/reference_casting.rs:122:9
--> $DIR/reference_casting.rs:128:9
|
LL | *(this as *const _ as *mut _) = a;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
error: aborting due to 35 previous errors
error: aborting due to 38 previous errors