mod crosspointer_transmute;
+mod transmute_float_to_int;
+mod transmute_int_to_bool;
mod transmute_int_to_char;
+mod transmute_int_to_float;
+mod transmute_num_to_bytes;
+mod transmute_ptr_to_ptr;
mod transmute_ptr_to_ref;
mod transmute_ref_to_ref;
+mod transmutes_expressible_as_ptr_casts;
+mod unsound_collection_transmute;
mod useless_transmute;
mod utils;
mod wrong_transmute;
-use utils::*;
-
-use crate::utils::{
- in_constant, match_def_path, paths, snippet, span_lint, span_lint_and_sugg, span_lint_and_then, sugg,
-};
+use clippy_utils::in_constant;
use if_chain::if_chain;
-use rustc_ast as ast;
-use rustc_errors::Applicability;
-use rustc_hir::{Expr, ExprKind, Mutability, UnOp};
+use rustc_hir::{Expr, ExprKind};
use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint};
-use std::borrow::Cow;
+use rustc_span::symbol::sym;
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes that can't ever be correct on any
+ /// ### What it does
+ /// Checks for transmutes that can't ever be correct on any
/// architecture.
///
- /// **Why is this bad?** It's basically guaranteed to be undefined behaviour.
+ /// ### Why is this bad?
+ /// It's basically guaranteed to be undefined behaviour.
///
- /// **Known problems:** When accessing C, users might want to store pointer
+ /// ### Known problems
+ /// When accessing C, users might want to store pointer
/// sized objects in `extradata` arguments to save an allocation.
///
- /// **Example:**
+ /// ### Example
/// ```ignore
/// let ptr: *const T = core::intrinsics::transmute('x')
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub WRONG_TRANSMUTE,
correctness,
"transmutes that are confusing at best, undefined behaviour at worst and always useless"
// FIXME: Move this to `complexity` again, after #5343 is fixed
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes to the original type of the object
+ /// ### What it does
+ /// Checks for transmutes to the original type of the object
/// and transmutes that could be a cast.
///
- /// **Why is this bad?** Readability. The code tricks people into thinking that
+ /// ### Why is this bad?
+ /// Readability. The code tricks people into thinking that
/// something complex is going on.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// core::intrinsics::transmute(t); // where the result type is the same as `t`'s
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub USELESS_TRANSMUTE,
nursery,
"transmutes that have the same to and from types or could be a cast/coercion"
// FIXME: Merge this lint with USELESS_TRANSMUTE once that is out of the nursery.
declare_clippy_lint! {
- /// **What it does:**Checks for transmutes that could be a pointer cast.
+ /// ### What it does
+ ///Checks for transmutes that could be a pointer cast.
///
- /// **Why is this bad?** Readability. The code tricks people into thinking that
+ /// ### Why is this bad?
+ /// Readability. The code tricks people into thinking that
/// something complex is going on.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
///
/// ```rust
/// # let p: *const [i32] = &[];
/// # let p: *const [i32] = &[];
/// p as *const [u16];
/// ```
+ #[clippy::version = "1.47.0"]
pub TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
complexity,
"transmutes that could be a pointer cast"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes between a type `T` and `*T`.
+ /// ### What it does
+ /// Checks for transmutes between a type `T` and `*T`.
///
- /// **Why is this bad?** It's easy to mistakenly transmute between a type and a
+ /// ### Why is this bad?
+ /// It's easy to mistakenly transmute between a type and a
/// pointer to that type.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// core::intrinsics::transmute(t) // where the result type is the same as
/// // `*t` or `&t`'s
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub CROSSPOINTER_TRANSMUTE,
complexity,
"transmutes that have to or from types that are a pointer to the other"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from a pointer to a reference.
+ /// ### What it does
+ /// Checks for transmutes from a pointer to a reference.
///
- /// **Why is this bad?** This can always be rewritten with `&` and `*`.
+ /// ### Why is this bad?
+ /// This can always be rewritten with `&` and `*`.
///
- /// **Known problems:**
+ /// ### Known problems
/// - `mem::transmute` in statics and constants is stable from Rust 1.46.0,
/// while dereferencing raw pointer is not stable yet.
/// If you need to do this in those places,
/// you would have to use `transmute` instead.
///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// unsafe {
/// let _: &T = std::mem::transmute(p); // where p: *const T
/// // can be written:
/// let _: &T = &*p;
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub TRANSMUTE_PTR_TO_REF,
complexity,
"transmutes from a pointer to a reference type"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from an integer to a `char`.
+ /// ### What it does
+ /// Checks for transmutes from an integer to a `char`.
///
- /// **Why is this bad?** Not every integer is a Unicode scalar value.
+ /// ### Why is this bad?
+ /// Not every integer is a Unicode scalar value.
///
- /// **Known problems:**
+ /// ### Known problems
/// - [`from_u32`] which this lint suggests using is slower than `transmute`
/// as it needs to validate the input.
/// If you are certain that the input is always a valid Unicode scalar value,
/// [`from_u32`]: https://doc.rust-lang.org/std/char/fn.from_u32.html
/// [`from_u32_unchecked`]: https://doc.rust-lang.org/std/char/fn.from_u32_unchecked.html
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let x = 1_u32;
/// unsafe {
/// // should be:
/// let _ = std::char::from_u32(x).unwrap();
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub TRANSMUTE_INT_TO_CHAR,
complexity,
"transmutes from an integer to a `char`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from a `&[u8]` to a `&str`.
+ /// ### What it does
+ /// Checks for transmutes from a `&[u8]` to a `&str`.
///
- /// **Why is this bad?** Not every byte slice is a valid UTF-8 string.
+ /// ### Why is this bad?
+ /// Not every byte slice is a valid UTF-8 string.
///
- /// **Known problems:**
+ /// ### Known problems
/// - [`from_utf8`] which this lint suggests using is slower than `transmute`
/// as it needs to validate the input.
/// If you are certain that the input is always a valid UTF-8,
/// [`from_utf8`]: https://doc.rust-lang.org/std/str/fn.from_utf8.html
/// [`from_utf8_unchecked`]: https://doc.rust-lang.org/std/str/fn.from_utf8_unchecked.html
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let b: &[u8] = &[1_u8, 2_u8];
/// unsafe {
/// // should be:
/// let _ = std::str::from_utf8(b).unwrap();
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub TRANSMUTE_BYTES_TO_STR,
complexity,
"transmutes from a `&[u8]` to a `&str`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from an integer to a `bool`.
- ///
- /// **Why is this bad?** This might result in an invalid in-memory representation of a `bool`.
+ /// ### What it does
+ /// Checks for transmutes from an integer to a `bool`.
///
- /// **Known problems:** None.
+ /// ### Why is this bad?
+ /// This might result in an invalid in-memory representation of a `bool`.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let x = 1_u8;
/// unsafe {
/// // should be:
/// let _: bool = x != 0;
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub TRANSMUTE_INT_TO_BOOL,
complexity,
"transmutes from an integer to a `bool`"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from an integer to a float.
+ /// ### What it does
+ /// Checks for transmutes from an integer to a float.
///
- /// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `from_bits` is intuitive
+ /// ### Why is this bad?
+ /// Transmutes are dangerous and error-prone, whereas `from_bits` is intuitive
/// and safe.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// unsafe {
/// let _: f32 = std::mem::transmute(1_u32); // where x: u32
/// // should be:
/// let _: f32 = f32::from_bits(1_u32);
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub TRANSMUTE_INT_TO_FLOAT,
complexity,
"transmutes from an integer to a float"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from a float to an integer.
+ /// ### What it does
+ /// Checks for transmutes from a float to an integer.
///
- /// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `to_bits` is intuitive
+ /// ### Why is this bad?
+ /// Transmutes are dangerous and error-prone, whereas `to_bits` is intuitive
/// and safe.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// unsafe {
/// let _: u32 = std::mem::transmute(1f32);
/// // should be:
/// let _: u32 = 1f32.to_bits();
/// ```
+ #[clippy::version = "1.41.0"]
pub TRANSMUTE_FLOAT_TO_INT,
complexity,
"transmutes from a float to an integer"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes from a pointer to a pointer, or
+ /// ### What it does
+ /// Checks for transmutes from a number to an array of `u8`
+ ///
+ /// ### Why this is bad?
+ /// Transmutes are dangerous and error-prone, whereas `to_ne_bytes`
+ /// is intuitive and safe.
+ ///
+ /// ### Example
+ /// ```rust
+ /// unsafe {
+ /// let x: [u8; 8] = std::mem::transmute(1i64);
+ /// }
+ ///
+ /// // should be
+ /// let x: [u8; 8] = 0i64.to_ne_bytes();
+ /// ```
+ #[clippy::version = "1.58.0"]
+ pub TRANSMUTE_NUM_TO_BYTES,
+ complexity,
+ "transmutes from a number to an array of `u8`"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for transmutes from a pointer to a pointer, or
/// from a reference to a reference.
///
- /// **Why is this bad?** Transmutes are dangerous, and these can instead be
+ /// ### Why is this bad?
+ /// Transmutes are dangerous, and these can instead be
/// written as casts.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// let ptr = &1u32 as *const u32;
/// unsafe {
/// let _ = ptr as *const f32;
/// let _ = unsafe{ &*(&1u32 as *const u32 as *const f32) };
/// ```
+ #[clippy::version = "pre 1.29.0"]
pub TRANSMUTE_PTR_TO_PTR,
- complexity,
+ pedantic,
"transmutes from a pointer to a pointer / a reference to a reference"
}
declare_clippy_lint! {
- /// **What it does:** Checks for transmutes between collections whose
+ /// ### What it does
+ /// Checks for transmutes between collections whose
/// types have different ABI, size or alignment.
///
- /// **Why is this bad?** This is undefined behavior.
+ /// ### Why is this bad?
+ /// This is undefined behavior.
///
- /// **Known problems:** Currently, we cannot know whether a type is a
+ /// ### Known problems
+ /// Currently, we cannot know whether a type is a
/// collection, so we just lint the ones that come with `std`.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// // different size, therefore likely out-of-bounds memory access
/// // You absolutely do not want this in your code!
/// ```rust
/// vec![2_u16].into_iter().map(u32::from).collect::<Vec<_>>();
/// ```
+ #[clippy::version = "1.40.0"]
pub UNSOUND_COLLECTION_TRANSMUTE,
correctness,
"transmute between collections of layout-incompatible types"
TRANSMUTE_INT_TO_BOOL,
TRANSMUTE_INT_TO_FLOAT,
TRANSMUTE_FLOAT_TO_INT,
+ TRANSMUTE_NUM_TO_BYTES,
UNSOUND_COLLECTION_TRANSMUTE,
TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
]);
-// used to check for UNSOUND_COLLECTION_TRANSMUTE
-static COLLECTIONS: &[&[&str]] = &[
- &paths::VEC,
- &paths::VEC_DEQUE,
- &paths::BINARY_HEAP,
- &paths::BTREESET,
- &paths::BTREEMAP,
- &paths::HASHSET,
- &paths::HASHMAP,
-];
-
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(ref path_expr, ref 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 match_def_path(cx, def_id, &paths::TRANSMUTE);
+ if cx.tcx.is_diagnostic_item(sym::transmute, def_id);
then {
// Avoid suggesting from/to bits and dereferencing raw pointers in const contexts.
// See https://github.com/rust-lang/rust/issues/73736 for progress on making them `const fn`.
// 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);
- let triggered = useless_transmute::check(cx, e, from_ty, to_ty, args);
- if triggered {
- return;
- }
- let triggered = wrong_transmute::check(cx, e, from_ty, to_ty);
- if triggered {
- return;
- }
- let triggered = crosspointer_transmute::check(cx, e, from_ty, to_ty);
- if triggered {
- return;
- }
- let triggered = transmute_ptr_to_ref::check(cx, e, from_ty, to_ty, args, qpath);
- if triggered {
+ // If useless_transmute is triggered, the other lints can be skipped.
+ if useless_transmute::check(cx, e, from_ty, to_ty, arg) {
return;
}
- let triggered = transmute_int_to_char::check(cx, e, from_ty, to_ty, args);
- if triggered {
- return;
- }
- let triggered = transmute_ref_to_ref::check(cx, e, from_ty, to_ty, args, const_context);
- if triggered {
- return;
- }
-
- match (&from_ty.kind(), &to_ty.kind()) {
- (ty::RawPtr(_), ty::RawPtr(to_ty)) => span_lint_and_then(
- cx,
- TRANSMUTE_PTR_TO_PTR,
- e.span,
- "transmute from a pointer to a pointer",
- |diag| {
- if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
- let sugg = arg.as_ty(cx.tcx.mk_ptr(*to_ty));
- diag.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
- }
- },
- ),
- (ty::Int(ty::IntTy::I8) | ty::Uint(ty::UintTy::U8), ty::Bool) => {
- span_lint_and_then(
- cx,
- TRANSMUTE_INT_TO_BOOL,
- e.span,
- &format!("transmute from a `{}` to a `bool`", from_ty),
- |diag| {
- let arg = sugg::Sugg::hir(cx, &args[0], "..");
- let zero = sugg::Sugg::NonParen(Cow::from("0"));
- diag.span_suggestion(
- e.span,
- "consider using",
- sugg::make_binop(ast::BinOpKind::Ne, &arg, &zero).to_string(),
- Applicability::Unspecified,
- );
- },
- )
- },
- (ty::Int(_) | ty::Uint(_), ty::Float(_)) if !const_context => span_lint_and_then(
- cx,
- TRANSMUTE_INT_TO_FLOAT,
- e.span,
- &format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
- |diag| {
- let arg = sugg::Sugg::hir(cx, &args[0], "..");
- let arg = if let ty::Int(int_ty) = from_ty.kind() {
- arg.as_ty(format!(
- "u{}",
- int_ty.bit_width().map_or_else(|| "size".to_string(), |v| v.to_string())
- ))
- } else {
- arg
- };
- diag.span_suggestion(
- e.span,
- "consider using",
- format!("{}::from_bits({})", to_ty, arg.to_string()),
- Applicability::Unspecified,
- );
- },
- ),
- (ty::Float(float_ty), ty::Int(_) | ty::Uint(_)) if !const_context => span_lint_and_then(
- cx,
- TRANSMUTE_FLOAT_TO_INT,
- 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, "..");
-
- if let ExprKind::Unary(UnOp::Neg, inner_expr) = &expr.kind {
- expr = &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
- let op = format!("{}{}", arg, float_ty.name_str()).into();
- if let ExprKind::Lit(lit) = &expr.kind;
- if let ast::LitKind::Float(_, ast::LitFloatType::Unsuffixed) = lit.node;
- then {
- match arg {
- sugg::Sugg::MaybeParen(_) => arg = sugg::Sugg::MaybeParen(op),
- _ => arg = sugg::Sugg::NonParen(op)
- }
- }
- }
-
- arg = sugg::Sugg::NonParen(format!("{}.to_bits()", arg.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())
- } else {
- arg
- };
+ 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);
- diag.span_suggestion(
- e.span,
- "consider using",
- arg.to_string(),
- Applicability::Unspecified,
- );
- },
- ),
- (ty::Adt(from_adt, from_substs), ty::Adt(to_adt, to_substs)) => {
- if from_adt.did != to_adt.did ||
- !COLLECTIONS.iter().any(|path| match_def_path(cx, to_adt.did, path)) {
- return;
- }
- if from_substs.types().zip(to_substs.types())
- .any(|(from_ty, to_ty)| is_layout_incompatible(cx, from_ty, to_ty)) {
- span_lint(
- cx,
- UNSOUND_COLLECTION_TRANSMUTE,
- e.span,
- &format!(
- "transmute from `{}` to `{}` with mismatched layout is unsound",
- from_ty,
- to_ty
- )
- );
- }
- },
- (_, _) if can_be_expressed_as_pointer_cast(cx, e, from_ty, to_ty) => span_lint_and_then(
- cx,
- TRANSMUTES_EXPRESSIBLE_AS_PTR_CASTS,
- e.span,
- &format!(
- "transmute from `{}` to `{}` which could be expressed as a pointer cast instead",
- from_ty,
- to_ty
- ),
- |diag| {
- if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
- let sugg = arg.as_ty(&to_ty.to_string()).to_string();
- diag.span_suggestion(e.span, "try", sugg, Applicability::MachineApplicable);
- }
- }
- ),
- _ => {
- return;
- },
+ if !linted {
+ transmutes_expressible_as_ptr_casts::check(cx, e, from_ty, to_ty, arg);
}
}
}
projects / rust.git / blobdiff