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Auto merge of #10520 - Nilstrieb:uninit, r=Alexendoo

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Use uninit checking from rustc

rustc has proper heuristics for actually checking whether a type allows being left uninitialized (by asking CTFE). We can now use this for our helper instead of rolling our own bad version with false positives.

I added this in rustc in rust-lang/rust#108669

Fix #10407

changelog: [`uninit_vec`]: fix false positives
changelog: [`uninit_assumed_init`]: fix false positives
This commit is contained in:
bors 2023-03-21 18:59:03 +00:00
commit 7b3c4aa771
5 changed files with 85 additions and 33 deletions
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19
clippy_utils/src/ty.rs
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@ -16,9 +16,9 @@
use rustc_lint::LateContext;
use rustc_middle::mir::interpret::{ConstValue, Scalar};
use rustc_middle::ty::{
self, AdtDef, AliasTy, AssocKind, Binder, BoundRegion, FnSig, IntTy, List, ParamEnv, Predicate, PredicateKind,
Region, RegionKind, SubstsRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor,
UintTy, VariantDef, VariantDiscr,
self, layout::ValidityRequirement, AdtDef, AliasTy, AssocKind, Binder, BoundRegion, FnSig, IntTy, List, ParamEnv,
Predicate, PredicateKind, Region, RegionKind, SubstsRef, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable,
TypeVisitableExt, TypeVisitor, UintTy, VariantDef, VariantDiscr,
};
use rustc_middle::ty::{GenericArg, GenericArgKind};
use rustc_span::symbol::Ident;
@ -538,13 +538,12 @@ pub fn same_type_and_consts<'tcx>(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
}
/// Checks if a given type looks safe to be uninitialized.
pub fn is_uninit_value_valid_for_ty(cx: &LateContext<'_>, ty: Ty<'_>) -> bool {
match *ty.kind() {
ty::Array(component, _) => is_uninit_value_valid_for_ty(cx, component),
ty::Tuple(types) => types.iter().all(|ty| is_uninit_value_valid_for_ty(cx, ty)),
ty::Adt(adt, _) => cx.tcx.lang_items().maybe_uninit() == Some(adt.did()),
_ => false,
}
pub fn is_uninit_value_valid_for_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
cx.tcx
.check_validity_requirement((ValidityRequirement::Uninit, cx.param_env.and(ty)))
// For types containing generic parameters we cannot get a layout to check.
// Therefore, we are conservative and assume that they don't allow uninit.
.unwrap_or(false)
}
/// Gets an iterator over all predicates which apply to the given item.

23
tests/ui/uninit.rs
View File

@ -3,13 +3,15 @@
use std::mem::{self, MaybeUninit};
union MyOwnMaybeUninit {
value: u8,
uninit: (),
}
fn main() {
let _: usize = unsafe { MaybeUninit::uninit().assume_init() };
// edge case: For now we lint on empty arrays
let _: [u8; 0] = unsafe { MaybeUninit::uninit().assume_init() };
// edge case: For now we accept unit tuples
// This is OK, because ZSTs do not contain data.
let _: () = unsafe { MaybeUninit::uninit().assume_init() };
// This is OK, because `MaybeUninit` allows uninitialized data.
@ -21,6 +23,19 @@ fn main() {
// This is OK, because all constitutent types are uninit-compatible.
let _: (MaybeUninit<usize>, [MaybeUninit<bool>; 2]) = unsafe { MaybeUninit::uninit().assume_init() };
// This is OK, because our own MaybeUninit is just as fine as the one from core.
let _: MyOwnMaybeUninit = unsafe { MaybeUninit::uninit().assume_init() };
// This is OK, because empty arrays don't contain data.
let _: [u8; 0] = unsafe { MaybeUninit::uninit().assume_init() };
// Was a false negative.
let _: usize = unsafe { mem::MaybeUninit::uninit().assume_init() };
polymorphic::<()>();
fn polymorphic<T>() {
// We are conservative around polymorphic types.
let _: T = unsafe { mem::MaybeUninit::uninit().assume_init() };
}
}

16
tests/ui/uninit.stderr
View File

@ -1,5 +1,5 @@
error: this call for this type may be undefined behavior
--> $DIR/uninit.rs:7:29
--> $DIR/uninit.rs:12:29
|
LL | let _: usize = unsafe { MaybeUninit::uninit().assume_init() };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -7,16 +7,16 @@ LL | let _: usize = unsafe { MaybeUninit::uninit().assume_init() };
= note: `#[deny(clippy::uninit_assumed_init)]` on by default
error: this call for this type may be undefined behavior
--> $DIR/uninit.rs:10:31
|
LL | let _: [u8; 0] = unsafe { MaybeUninit::uninit().assume_init() };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: this call for this type may be undefined behavior
--> $DIR/uninit.rs:25:29
--> $DIR/uninit.rs:33:29
|
LL | let _: usize = unsafe { mem::MaybeUninit::uninit().assume_init() };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: this call for this type may be undefined behavior
--> $DIR/uninit.rs:39:29
|
LL | let _: T = unsafe { mem::MaybeUninit::uninit().assume_init() };
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 3 previous errors

27
tests/ui/uninit_vec.rs
View File

@ -7,6 +7,11 @@ struct MyVec {
vec: Vec<u8>,
}
union MyOwnMaybeUninit {
value: u8,
uninit: (),
}
fn main() {
// with_capacity() -> set_len() should be detected
let mut vec: Vec<u8> = Vec::with_capacity(1000);
@ -97,4 +102,26 @@ fn main() {
unsafe {
vec.set_len(0);
}
// ZSTs should not be detected
let mut vec: Vec<()> = Vec::with_capacity(1000);
unsafe {
vec.set_len(10);
}
// unions should not be detected
let mut vec: Vec<MyOwnMaybeUninit> = Vec::with_capacity(1000);
unsafe {
vec.set_len(10);
}
polymorphic::<()>();
fn polymorphic<T>() {
// We are conservative around polymorphic types.
let mut vec: Vec<T> = Vec::with_capacity(1000);
unsafe {
vec.set_len(10);
}
}
}

33
tests/ui/uninit_vec.stderr
View File

@ -1,5 +1,5 @@
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:12:5
--> $DIR/uninit_vec.rs:17:5
|
LL | let mut vec: Vec<u8> = Vec::with_capacity(1000);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -11,7 +11,7 @@ LL | vec.set_len(200);
= note: `-D clippy::uninit-vec` implied by `-D warnings`
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:18:5
--> $DIR/uninit_vec.rs:23:5
|
LL | vec.reserve(1000);
| ^^^^^^^^^^^^^^^^^^
@ -22,7 +22,7 @@ LL | vec.set_len(200);
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: calling `set_len()` on empty `Vec` creates out-of-bound values
--> $DIR/uninit_vec.rs:24:5
--> $DIR/uninit_vec.rs:29:5
|
LL | let mut vec: Vec<u8> = Vec::new();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -31,7 +31,7 @@ LL | vec.set_len(200);
| ^^^^^^^^^^^^^^^^
error: calling `set_len()` on empty `Vec` creates out-of-bound values
--> $DIR/uninit_vec.rs:30:5
--> $DIR/uninit_vec.rs:35:5
|
LL | let mut vec: Vec<u8> = Default::default();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -40,7 +40,7 @@ LL | vec.set_len(200);
| ^^^^^^^^^^^^^^^^
error: calling `set_len()` on empty `Vec` creates out-of-bound values
--> $DIR/uninit_vec.rs:35:5
--> $DIR/uninit_vec.rs:40:5
|
LL | let mut vec: Vec<u8> = Vec::default();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -49,7 +49,7 @@ LL | vec.set_len(200);
| ^^^^^^^^^^^^^^^^
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:49:5
--> $DIR/uninit_vec.rs:54:5
|
LL | let mut vec: Vec<u8> = Vec::with_capacity(1000);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -60,7 +60,7 @@ LL | vec.set_len(200);
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:58:5
--> $DIR/uninit_vec.rs:63:5
|
LL | my_vec.vec.reserve(1000);
| ^^^^^^^^^^^^^^^^^^^^^^^^^
@ -71,7 +71,7 @@ LL | my_vec.vec.set_len(200);
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:63:5
--> $DIR/uninit_vec.rs:68:5
|
LL | my_vec.vec = Vec::with_capacity(1000);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -82,7 +82,7 @@ LL | my_vec.vec.set_len(200);
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:42:9
--> $DIR/uninit_vec.rs:47:9
|
LL | let mut vec: Vec<u8> = Vec::with_capacity(1000);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@ -92,7 +92,7 @@ LL | vec.set_len(200);
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:45:9
--> $DIR/uninit_vec.rs:50:9
|
LL | vec.reserve(1000);
| ^^^^^^^^^^^^^^^^^^
@ -101,5 +101,16 @@ LL | vec.set_len(200);
|
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: aborting due to 10 previous errors
error: calling `set_len()` immediately after reserving a buffer creates uninitialized values
--> $DIR/uninit_vec.rs:122:9
|
LL | let mut vec: Vec<T> = Vec::with_capacity(1000);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
LL | unsafe {
LL | vec.set_len(10);
| ^^^^^^^^^^^^^^^
|
= help: initialize the buffer or wrap the content in `MaybeUninit`
error: aborting due to 11 previous errors