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Auto merge of #8398 - Jarcho:unordered_transmute, r=llogiq

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Add lint `transmute_undefined_repr`

Partially implements #3999 and #546

This doesn't consider `enum`s at all right now as those are going to be a pain to deal with. This also allows `#[repr(Rust)]` structs with only one non-zero sized fields. I think those are technically undefined when transmuted.

changelog: Add lint `transmute_undefined_repr`
This commit is contained in:
bors 2022-02-06 16:05:00 +00:00
commit 093e32052e
20 changed files with 463 additions and 51 deletions
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1
CHANGELOG.md
View file

@ -3475,6 +3475,7 @@ Released 2018-09-13
[`transmute_num_to_bytes`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_num_to_bytes
[`transmute_ptr_to_ptr`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_ptr_to_ptr
[`transmute_ptr_to_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_ptr_to_ref
[`transmute_undefined_repr`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmute_undefined_repr
[`transmutes_expressible_as_ptr_casts`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmutes_expressible_as_ptr_casts
[`transmuting_null`]: https://rust-lang.github.io/rust-clippy/master/index.html#transmuting_null
[`trivial_regex`]: https://rust-lang.github.io/rust-clippy/master/index.html#trivial_regex

1
clippy_lints/src/lib.register_all.rs
View file

@ -277,6 +277,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
LintId::of(transmute::TRANSMUTE_INT_TO_FLOAT),
LintId::of(transmute::TRANSMUTE_NUM_TO_BYTES),
LintId::of(transmute::TRANSMUTE_PTR_TO_REF),
LintId::of(transmute::TRANSMUTE_UNDEFINED_REPR),
LintId::of(transmute::UNSOUND_COLLECTION_TRANSMUTE),
LintId::of(transmute::WRONG_TRANSMUTE),
LintId::of(transmuting_null::TRANSMUTING_NULL),

1
clippy_lints/src/lib.register_correctness.rs
View file

@ -58,6 +58,7 @@ store.register_group(true, "clippy::correctness", Some("clippy_correctness"), ve
LintId::of(size_of_in_element_count::SIZE_OF_IN_ELEMENT_COUNT),
LintId::of(swap::ALMOST_SWAPPED),
LintId::of(to_string_in_display::TO_STRING_IN_DISPLAY),
LintId::of(transmute::TRANSMUTE_UNDEFINED_REPR),
LintId::of(transmute::UNSOUND_COLLECTION_TRANSMUTE),
LintId::of(transmute::WRONG_TRANSMUTE),
LintId::of(transmuting_null::TRANSMUTING_NULL),

1
clippy_lints/src/lib.register_lints.rs
View file

@ -473,6 +473,7 @@ store.register_lints(&[
transmute::TRANSMUTE_NUM_TO_BYTES,
transmute::TRANSMUTE_PTR_TO_PTR,
transmute::TRANSMUTE_PTR_TO_REF,
transmute::TRANSMUTE_UNDEFINED_REPR,
transmute::UNSOUND_COLLECTION_TRANSMUTE,
transmute::USELESS_TRANSMUTE,
transmute::WRONG_TRANSMUTE,

1
clippy_lints/src/lib.rs
View file

@ -5,6 +5,7 @@
#![feature(control_flow_enum)]
#![feature(drain_filter)]
#![feature(iter_intersperse)]
#![feature(let_chains)]
#![feature(let_else)]
#![feature(once_cell)]
#![feature(rustc_private)]

60
clippy_lints/src/transmute/mod.rs
View file

@ -7,6 +7,7 @@ mod transmute_num_to_bytes;
mod transmute_ptr_to_ptr;
mod transmute_ptr_to_ref;
mod transmute_ref_to_ref;
mod transmute_undefined_repr;
mod transmutes_expressible_as_ptr_casts;
mod unsound_collection_transmute;
mod useless_transmute;
@ -355,6 +356,30 @@ declare_clippy_lint! {
"transmute between collections of layout-incompatible types"
}
declare_clippy_lint! {
/// ### What it does
/// Checks for transmutes either to or from a type which does not have a defined representation.
///
/// ### Why is this bad?
/// The results of such a transmute are not defined.
///
/// ### Example
/// ```rust
/// struct Foo<T>(u32, T);
/// let _ = unsafe { core::mem::transmute::<Foo<u32>, Foo<i32>>(Foo(0u32, 0u32)) };
/// ```
/// Use instead:
/// ```rust
/// #[repr(C)]
/// struct Foo<T>(u32, T);
/// let _ = unsafe { core::mem::transmute::<Foo<u32>, Foo<i32>>(Foo(0u32, 0u32)) };
/// ```
#[clippy::version = "1.60.0"]
pub TRANSMUTE_UNDEFINED_REPR,
correctness,
"transmute to or from a type with an undefined representation"
}
declare_lint_pass!(Transmute => [
CROSSPOINTER_TRANSMUTE,
TRANSMUTE_PTR_TO_REF,
@ -369,13 +394,13 @@ declare_lint_pass!(Transmute => [
TRANSMUTE_NUM_TO_BYTES,
UNSOUND_COLLECTION_TRANSMUTE,
TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
TRANSMUTE_UNDEFINED_REPR,
]);
impl<'tcx> LateLintPass<'tcx> for Transmute {
#[allow(clippy::similar_names, clippy::too_many_lines)]
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx Expr<'_>) {
if_chain! {
if let ExprKind::Call(path_expr, args) = e.kind;
if let ExprKind::Call(path_expr, [arg]) = e.kind;
if let ExprKind::Path(ref qpath) = path_expr.kind;
if let Some(def_id) = cx.qpath_res(qpath, path_expr.hir_id).opt_def_id();
if cx.tcx.is_diagnostic_item(sym::transmute, def_id);
@ -385,28 +410,31 @@ impl<'tcx> LateLintPass<'tcx> for Transmute {
// And see https://github.com/rust-lang/rust/issues/51911 for dereferencing raw pointers.
let const_context = in_constant(cx, e.hir_id);
let from_ty = cx.typeck_results().expr_ty(&args[0]);
let from_ty = cx.typeck_results().expr_ty(arg);
let to_ty = cx.typeck_results().expr_ty(e);
// If useless_transmute is triggered, the other lints can be skipped.
if useless_transmute::check(cx, e, from_ty, to_ty, args) {
if useless_transmute::check(cx, e, from_ty, to_ty, arg) {
return;
}
let mut linted = wrong_transmute::check(cx, e, from_ty, to_ty);
linted |= crosspointer_transmute::check(cx, e, from_ty, to_ty);
linted |= transmute_ptr_to_ref::check(cx, e, from_ty, to_ty, args, qpath);
linted |= transmute_int_to_char::check(cx, e, from_ty, to_ty, args);
linted |= transmute_ref_to_ref::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_ptr_to_ptr::check(cx, e, from_ty, to_ty, args);
linted |= transmute_int_to_bool::check(cx, e, from_ty, to_ty, args);
linted |= transmute_int_to_float::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_float_to_int::check(cx, e, from_ty, to_ty, args, const_context);
linted |= transmute_num_to_bytes::check(cx, e, from_ty, to_ty, args, const_context);
linted |= unsound_collection_transmute::check(cx, e, from_ty, to_ty);
let linted = wrong_transmute::check(cx, e, from_ty, to_ty)
| crosspointer_transmute::check(cx, e, from_ty, to_ty)
| transmute_ptr_to_ref::check(cx, e, from_ty, to_ty, arg, qpath)
| transmute_int_to_char::check(cx, e, from_ty, to_ty, arg)
| transmute_ref_to_ref::check(cx, e, from_ty, to_ty, arg, const_context)
| transmute_ptr_to_ptr::check(cx, e, from_ty, to_ty, arg)
| transmute_int_to_bool::check(cx, e, from_ty, to_ty, arg)
| transmute_int_to_float::check(cx, e, from_ty, to_ty, arg, const_context)
| transmute_float_to_int::check(cx, e, from_ty, to_ty, arg, const_context)
| transmute_num_to_bytes::check(cx, e, from_ty, to_ty, arg, const_context)
| (
unsound_collection_transmute::check(cx, e, from_ty, to_ty)
|| transmute_undefined_repr::check(cx, e, from_ty, to_ty)
);
if !linted {
transmutes_expressible_as_ptr_casts::check(cx, e, from_ty, to_ty, args);
transmutes_expressible_as_ptr_casts::check(cx, e, from_ty, to_ty, arg);
}
}
}

29
clippy_lints/src/transmute/transmute_float_to_int.rs
View file

@ -15,7 +15,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
mut arg: &'tcx Expr<'_>,
const_context: bool,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
@ -26,37 +26,36 @@ pub(super) fn check<'tcx>(
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let mut expr = &args[0];
let mut arg = sugg::Sugg::hir(cx, expr, "..");
let mut sugg = sugg::Sugg::hir(cx, arg, "..");
if let ExprKind::Unary(UnOp::Neg, inner_expr) = &expr.kind {
expr = inner_expr;
if let ExprKind::Unary(UnOp::Neg, inner_expr) = &arg.kind {
arg = inner_expr;
}
if_chain! {
// if the expression is a float literal and it is unsuffixed then
// add a suffix so the suggestion is valid and unambiguous
if let ExprKind::Lit(lit) = &expr.kind;
if let ExprKind::Lit(lit) = &arg.kind;
if let ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) = lit.node;
then {
let op = format!("{}{}", arg, float_ty.name_str()).into();
match arg {
sugg::Sugg::MaybeParen(_) => arg = sugg::Sugg::MaybeParen(op),
_ => arg = sugg::Sugg::NonParen(op)
let op = format!("{}{}", sugg, float_ty.name_str()).into();
match sugg {
sugg::Sugg::MaybeParen(_) => sugg = sugg::Sugg::MaybeParen(op),
_ => sugg = sugg::Sugg::NonParen(op)
}
}
}
arg = sugg::Sugg::NonParen(format!("{}.to_bits()", arg.maybe_par()).into());
sugg = sugg::Sugg::NonParen(format!("{}.to_bits()", sugg.maybe_par()).into());
// cast the result of `to_bits` if `to_ty` is signed
arg = if let ty::Int(int_ty) = to_ty.kind() {
arg.as_ty(int_ty.name_str().to_string())
sugg = if let ty::Int(int_ty) = to_ty.kind() {
sugg.as_ty(int_ty.name_str().to_string())
} else {
arg
sugg
};
diag.span_suggestion(e.span, "consider using", arg.to_string(), Applicability::Unspecified);
diag.span_suggestion(e.span, "consider using", sugg.to_string(), Applicability::Unspecified);
},
);
true

4
clippy_lints/src/transmute/transmute_int_to_bool.rs
View file

@ -15,7 +15,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::Int(ty::IntTy::I8) | ty::Uint(ty::UintTy::U8), ty::Bool) => {
@ -25,7 +25,7 @@ pub(super) fn check<'tcx>(
e.span,
&format!("transmute from a `{}` to a `bool`", from_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = sugg::Sugg::hir(cx, arg, "..");
let zero = sugg::Sugg::NonParen(Cow::from("0"));
diag.span_suggestion(
e.span,

4
clippy_lints/src/transmute/transmute_int_to_char.rs
View file

@ -14,7 +14,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::Int(ty::IntTy::I32) | ty::Uint(ty::UintTy::U32), &ty::Char) => {
@ -24,7 +24,7 @@ pub(super) fn check<'tcx>(
e.span,
&format!("transmute from a `{}` to a `char`", from_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = sugg::Sugg::hir(cx, arg, "..");
let arg = if let ty::Int(_) = from_ty.kind() {
arg.as_ty(ast::UintTy::U32.name_str())
} else {

4
clippy_lints/src/transmute/transmute_int_to_float.rs
View file

@ -13,7 +13,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
const_context: bool,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
@ -24,7 +24,7 @@ pub(super) fn check<'tcx>(
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = sugg::Sugg::hir(cx, arg, "..");
let arg = if let ty::Int(int_ty) = from_ty.kind() {
arg.as_ty(format!(
"u{}",

4
clippy_lints/src/transmute/transmute_num_to_bytes.rs
View file

@ -13,7 +13,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
const_context: bool,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
@ -33,7 +33,7 @@ pub(super) fn check<'tcx>(
e.span,
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = sugg::Sugg::hir(cx, arg, "..");
diag.span_suggestion(
e.span,
"consider using `to_ne_bytes()`",

4
clippy_lints/src/transmute/transmute_ptr_to_ptr.rs
View file

@ -13,7 +13,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::RawPtr(_), ty::RawPtr(to_ty)) => {
@ -23,7 +23,7 @@ pub(super) fn check<'tcx>(
e.span,
"transmute from a pointer to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
let sugg = arg.as_ty(cx.tcx.mk_ptr(*to_ty));
diag.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
}

4
clippy_lints/src/transmute/transmute_ptr_to_ref.rs
View file

@ -14,7 +14,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
qpath: &'tcx QPath<'_>,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
@ -28,7 +28,7 @@ pub(super) fn check<'tcx>(
from_ty, to_ty
),
|diag| {
let arg = sugg::Sugg::hir(cx, &args[0], "..");
let arg = sugg::Sugg::hir(cx, arg, "..");
let (deref, cast) = if *mutbl == Mutability::Mut {
("&mut *", "*mut")
} else {

6
clippy_lints/src/transmute/transmute_ref_to_ref.rs
View file

@ -15,7 +15,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
const_context: bool,
) -> bool {
let mut triggered = false;
@ -41,7 +41,7 @@ pub(super) fn check<'tcx>(
format!(
"std::str::from_utf8{}({}).unwrap()",
postfix,
snippet(cx, args[0].span, ".."),
snippet(cx, arg.span, ".."),
),
Applicability::Unspecified,
);
@ -54,7 +54,7 @@ pub(super) fn check<'tcx>(
TRANSMUTE_PTR_TO_PTR,
e.span,
"transmute from a reference to a reference",
|diag| if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
|diag| if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
let ty_from_and_mut = ty::TypeAndMut {
ty: ty_from,
mutbl: *from_mutbl

291
clippy_lints/src/transmute/transmute_undefined_repr.rs Normal file
View file

@ -0,0 +1,291 @@
use super::TRANSMUTE_UNDEFINED_REPR;
use clippy_utils::diagnostics::span_lint_and_then;
use rustc_hir::Expr;
use rustc_lint::LateContext;
use rustc_middle::ty::subst::{GenericArg, Subst};
use rustc_middle::ty::{self, Ty, TyS, TypeAndMut};
use rustc_span::Span;
#[allow(clippy::too_many_lines)]
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty_orig: Ty<'tcx>,
to_ty_orig: Ty<'tcx>,
) -> bool {
let mut from_ty = cx.tcx.erase_regions(from_ty_orig);
let mut to_ty = cx.tcx.erase_regions(to_ty_orig);
while !TyS::same_type(from_ty, to_ty) {
match reduce_refs(cx, e.span, from_ty, to_ty) {
ReducedTys::FromFatPtr { unsized_ty, .. } => {
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!("transmute from `{}` which has an undefined layout", from_ty_orig),
|diag| {
if !TyS::same_type(from_ty_orig.peel_refs(), unsized_ty) {
diag.note(&format!("the contained type `&{}` has an undefined layout", unsized_ty));
}
},
);
return true;
},
ReducedTys::ToFatPtr { unsized_ty, .. } => {
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!("transmute to `{}` which has an undefined layout", to_ty_orig),
|diag| {
if !TyS::same_type(to_ty_orig.peel_refs(), unsized_ty) {
diag.note(&format!("the contained type `&{}` has an undefined layout", unsized_ty));
}
},
);
return true;
},
ReducedTys::ToPtr {
from_ty: from_sub_ty,
to_ty: to_sub_ty,
} => match reduce_ty(cx, from_sub_ty) {
ReducedTy::UnorderedFields(from_ty) => {
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!("transmute from `{}` which has an undefined layout", from_ty_orig),
|diag| {
if !TyS::same_type(from_ty_orig.peel_refs(), from_ty) {
diag.note(&format!("the contained type `{}` has an undefined layout", from_ty));
}
},
);
return true;
},
ReducedTy::Ref(from_sub_ty) => {
from_ty = from_sub_ty;
to_ty = to_sub_ty;
continue;
},
_ => break,
},
ReducedTys::FromPtr {
from_ty: from_sub_ty,
to_ty: to_sub_ty,
} => match reduce_ty(cx, to_sub_ty) {
ReducedTy::UnorderedFields(to_ty) => {
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!("transmute to `{}` which has an undefined layout", to_ty_orig),
|diag| {
if !TyS::same_type(to_ty_orig.peel_refs(), to_ty) {
diag.note(&format!("the contained type `{}` has an undefined layout", to_ty));
}
},
);
return true;
},
ReducedTy::Ref(to_sub_ty) => {
from_ty = from_sub_ty;
to_ty = to_sub_ty;
continue;
},
_ => break,
},
ReducedTys::Other {
from_ty: from_sub_ty,
to_ty: to_sub_ty,
} => match (reduce_ty(cx, from_sub_ty), reduce_ty(cx, to_sub_ty)) {
(ReducedTy::IntArray, _) | (_, ReducedTy::IntArray) => return false,
(ReducedTy::UnorderedFields(from_ty), ReducedTy::UnorderedFields(to_ty))
if !TyS::same_type(from_ty, to_ty) =>
{
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!(
"transmute from `{}` to `{}`, both of which have an undefined layout",
from_ty_orig, to_ty_orig
),
|diag| {
if let (Some(from_def), Some(to_def)) = (from_ty.ty_adt_def(), to_ty.ty_adt_def())
&& from_def == to_def
{
diag.note(&format!(
"two instances of the same generic type (`{}`) may have different layouts",
cx.tcx.item_name(from_def.did)
));
} else {
if !TyS::same_type(from_ty_orig.peel_refs(), from_ty) {
diag.note(&format!("the contained type `{}` has an undefined layout", from_ty));
}
if !TyS::same_type(to_ty_orig.peel_refs(), to_ty) {
diag.note(&format!("the contained type `{}` has an undefined layout", to_ty));
}
}
},
);
return true;
},
(
ReducedTy::UnorderedFields(from_ty),
ReducedTy::Other(_) | ReducedTy::OrderedFields(_) | ReducedTy::Ref(_),
) => {
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!("transmute from `{}` which has an undefined layout", from_ty_orig),
|diag| {
if !TyS::same_type(from_ty_orig.peel_refs(), from_ty) {
diag.note(&format!("the contained type `{}` has an undefined layout", from_ty));
}
},
);
return true;
},
(
ReducedTy::Other(_) | ReducedTy::OrderedFields(_) | ReducedTy::Ref(_),
ReducedTy::UnorderedFields(to_ty),
) => {
span_lint_and_then(
cx,
TRANSMUTE_UNDEFINED_REPR,
e.span,
&format!("transmute into `{}` which has an undefined layout", to_ty_orig),
|diag| {
if !TyS::same_type(to_ty_orig.peel_refs(), to_ty) {
diag.note(&format!("the contained type `{}` has an undefined layout", to_ty));
}
},
);
return true;
},
(ReducedTy::Ref(from_sub_ty), ReducedTy::Ref(to_sub_ty)) => {
from_ty = from_sub_ty;
to_ty = to_sub_ty;
continue;
},
(
ReducedTy::OrderedFields(_) | ReducedTy::Ref(_) | ReducedTy::Other(_),
ReducedTy::OrderedFields(_) | ReducedTy::Ref(_) | ReducedTy::Other(_),
)
| (ReducedTy::UnorderedFields(_), ReducedTy::UnorderedFields(_)) => break,
},
}
}
false
}
enum ReducedTys<'tcx> {
FromFatPtr { unsized_ty: Ty<'tcx> },
ToFatPtr { unsized_ty: Ty<'tcx> },
ToPtr { from_ty: Ty<'tcx>, to_ty: Ty<'tcx> },
FromPtr { from_ty: Ty<'tcx>, to_ty: Ty<'tcx> },
Other { from_ty: Ty<'tcx>, to_ty: Ty<'tcx> },
}
fn reduce_refs<'tcx>(
cx: &LateContext<'tcx>,
span: Span,
mut from_ty: Ty<'tcx>,
mut to_ty: Ty<'tcx>,
) -> ReducedTys<'tcx> {
loop {
return match (from_ty.kind(), to_ty.kind()) {
(
ty::Ref(_, from_sub_ty, _) | ty::RawPtr(TypeAndMut { ty: from_sub_ty, .. }),
ty::Ref(_, to_sub_ty, _) | ty::RawPtr(TypeAndMut { ty: to_sub_ty, .. }),
) => {
from_ty = from_sub_ty;
to_ty = to_sub_ty;
continue;
},
(ty::Ref(_, unsized_ty, _) | ty::RawPtr(TypeAndMut { ty: unsized_ty, .. }), _)
if !unsized_ty.is_sized(cx.tcx.at(span), cx.param_env) =>
{
ReducedTys::FromFatPtr { unsized_ty }
},
(_, ty::Ref(_, unsized_ty, _) | ty::RawPtr(TypeAndMut { ty: unsized_ty, .. }))
if !unsized_ty.is_sized(cx.tcx.at(span), cx.param_env) =>
{
ReducedTys::ToFatPtr { unsized_ty }
},
(ty::Ref(_, from_ty, _) | ty::RawPtr(TypeAndMut { ty: from_ty, .. }), _) => {
ReducedTys::FromPtr { from_ty, to_ty }
},
(_, ty::Ref(_, to_ty, _) | ty::RawPtr(TypeAndMut { ty: to_ty, .. })) => {
ReducedTys::ToPtr { from_ty, to_ty }
},
_ => ReducedTys::Other { from_ty, to_ty },
};
}
}
enum ReducedTy<'tcx> {
OrderedFields(Ty<'tcx>),
UnorderedFields(Ty<'tcx>),
Ref(Ty<'tcx>),
Other(Ty<'tcx>),
IntArray,
}
fn reduce_ty<'tcx>(cx: &LateContext<'tcx>, mut ty: Ty<'tcx>) -> ReducedTy<'tcx> {
loop {
ty = cx.tcx.try_normalize_erasing_regions(cx.param_env, ty).unwrap_or(ty);
return match *ty.kind() {
ty::Array(sub_ty, _) if matches!(sub_ty.kind(), ty::Int(_) | ty::Uint(_)) => ReducedTy::IntArray,
ty::Array(sub_ty, _) | ty::Slice(sub_ty) => {
ty = sub_ty;
continue;
},
ty::Tuple(args) => {
let mut iter = args.iter().map(GenericArg::expect_ty);
let Some(sized_ty) = iter.find(|ty| !is_zero_sized_ty(cx, ty)) else {
return ReducedTy::OrderedFields(ty);
};
if iter.all(|ty| is_zero_sized_ty(cx, ty)) {
ty = sized_ty;
continue;
}
ReducedTy::UnorderedFields(ty)
},
ty::Adt(def, substs) if def.is_struct() => {
if def.repr.inhibit_struct_field_reordering_opt() {
return ReducedTy::OrderedFields(ty);
}
let mut iter = def
.non_enum_variant()
.fields
.iter()
.map(|f| cx.tcx.type_of(f.did).subst(cx.tcx, substs));
let Some(sized_ty) = iter.find(|ty| !is_zero_sized_ty(cx, ty)) else {
return ReducedTy::OrderedFields(ty);
};
if iter.all(|ty| is_zero_sized_ty(cx, ty)) {
ty = sized_ty;
continue;
}
ReducedTy::UnorderedFields(ty)
},
ty::Ref(..) | ty::RawPtr(_) => ReducedTy::Ref(ty),
_ => ReducedTy::Other(ty),
};
}
}
fn is_zero_sized_ty<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> bool {
if let Ok(ty) = cx.tcx.try_normalize_erasing_regions(cx.param_env, ty)
&& let Ok(layout) = cx.tcx.layout_of(cx.param_env.and(ty))
{
layout.layout.size.bytes() == 0
} else {
false
}
}

4
clippy_lints/src/transmute/transmutes_expressible_as_ptr_casts.rs
View file

@ -14,7 +14,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
) -> bool {
if can_be_expressed_as_pointer_cast(cx, e, from_ty, to_ty) {
span_lint_and_then(
@ -26,7 +26,7 @@ pub(super) fn check<'tcx>(
from_ty, to_ty
),
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
let sugg = arg.as_ty(&to_ty.to_string()).to_string();
diag.span_suggestion(e.span, "try", sugg, Applicability::MachineApplicable);
}

6
clippy_lints/src/transmute/useless_transmute.rs
View file

@ -13,7 +13,7 @@ pub(super) fn check<'tcx>(
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
args: &'tcx [Expr<'_>],
arg: &'tcx Expr<'_>,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
_ if from_ty == to_ty => {
@ -32,7 +32,7 @@ pub(super) fn check<'tcx>(
e.span,
"transmute from a reference to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
let rty_and_mut = ty::TypeAndMut {
ty: rty,
mutbl: *rty_mutbl,
@ -57,7 +57,7 @@ pub(super) fn check<'tcx>(
e.span,
"transmute from an integer to a pointer",
|diag| {
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
if let Some(arg) = sugg::Sugg::hir_opt(cx, arg) {
diag.span_suggestion(
e.span,
"try",

1
tests/ui/crashes/ice-4968.rs
View file

@ -3,6 +3,7 @@
// Test for https://github.com/rust-lang/rust-clippy/issues/4968
#![warn(clippy::unsound_collection_transmute)]
#![allow(clippy::transmute_undefined_repr)]
trait Trait {
type Assoc;

44
tests/ui/transmute_undefined_repr.rs Normal file
View file

@ -0,0 +1,44 @@
#![warn(clippy::transmute_undefined_repr)]
#![allow(clippy::unit_arg)]
fn value<T>() -> T {
unimplemented!()
}
struct Empty;
struct Ty<T>(T);
struct Ty2<T, U>(T, U);
#[repr(C)]
struct Ty2C<T, U>(T, U);
fn main() {
unsafe {
let _: () = core::mem::transmute(value::<Empty>());
let _: Empty = core::mem::transmute(value::<()>());
let _: Ty<u32> = core::mem::transmute(value::<u32>());
let _: Ty<u32> = core::mem::transmute(value::<u32>());
let _: Ty2C<u32, i32> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty<Ty2<u32, i32>>>()); // Ok, Ty2 types are the same
let _: Ty<Ty2<u32, i32>> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Ok, Ty2 types are the same
let _: Ty2<u32, f32> = core::mem::transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
let _: Ty<Ty2<u32, i32>> = core::mem::transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
let _: Ty<&()> = core::mem::transmute(value::<&()>());
let _: &() = core::mem::transmute(value::<Ty<&()>>());
let _: &Ty2<u32, f32> = core::mem::transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
let _: Ty<&Ty2<u32, i32>> = core::mem::transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
let _: Ty<usize> = core::mem::transmute(value::<&Ty2<u32, i32>>()); // Ok, pointer to usize conversion
let _: &Ty2<u32, i32> = core::mem::transmute(value::<Ty<usize>>()); // Ok, pointer to usize conversion
let _: Ty<[u8; 8]> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Ok, transmute to byte array
let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty<[u8; 8]>>()); // Ok, transmute from byte array
}
}

44
tests/ui/transmute_undefined_repr.stderr Normal file
View file

@ -0,0 +1,44 @@
error: transmute from `Ty2<u32, i32>` which has an undefined layout
--> $DIR/transmute_undefined_repr.rs:23:33
|
LL | let _: Ty2C<u32, i32> = core::mem::transmute(value::<Ty2<u32, i32>>()); // Lint, Ty2 is unordered
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: `-D clippy::transmute-undefined-repr` implied by `-D warnings`
error: transmute into `Ty2<u32, i32>` which has an undefined layout
--> $DIR/transmute_undefined_repr.rs:24:32
|
LL | let _: Ty2<u32, i32> = core::mem::transmute(value::<Ty2C<u32, i32>>()); // Lint, Ty2 is unordered
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from `Ty<Ty2<u32, i32>>` to `Ty2<u32, f32>`, both of which have an undefined layout
--> $DIR/transmute_undefined_repr.rs:29:32
|
LL | let _: Ty2<u32, f32> = core::mem::transmute(value::<Ty<Ty2<u32, i32>>>()); // Lint, different Ty2 instances
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: two instances of the same generic type (`Ty2`) may have different layouts
error: transmute from `Ty2<u32, f32>` to `Ty<Ty2<u32, i32>>`, both of which have an undefined layout
--> $DIR/transmute_undefined_repr.rs:30:36
|
LL | let _: Ty<Ty2<u32, i32>> = core::mem::transmute(value::<Ty2<u32, f32>>()); // Lint, different Ty2 instances
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: two instances of the same generic type (`Ty2`) may have different layouts
error: transmute to `&Ty2<u32, f32>` which has an undefined layout
--> $DIR/transmute_undefined_repr.rs:35:33
|
LL | let _: &Ty2<u32, f32> = core::mem::transmute(value::<Ty<&Ty2<u32, i32>>>()); // Lint, different Ty2 instances
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: transmute from `&Ty2<u32, f32>` which has an undefined layout
--> $DIR/transmute_undefined_repr.rs:36:37
|
LL | let _: Ty<&Ty2<u32, i32>> = core::mem::transmute(value::<&Ty2<u32, f32>>()); // Lint, different Ty2 instances
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
error: aborting due to 6 previous errors