764 lines
31 KiB
Rust
764 lines
31 KiB
Rust
use crate::utils::{
|
|
in_constant, is_normalizable, last_path_segment, match_def_path, paths, snippet, span_lint, span_lint_and_sugg,
|
|
span_lint_and_then, sugg,
|
|
};
|
|
use if_chain::if_chain;
|
|
use rustc_ast as ast;
|
|
use rustc_errors::Applicability;
|
|
use rustc_hir::{Expr, ExprKind, GenericArg, Mutability, QPath, TyKind, UnOp};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_middle::ty::{self, cast::CastKind, Ty};
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
use rustc_span::DUMMY_SP;
|
|
use rustc_typeck::check::{cast::CastCheck, FnCtxt, Inherited};
|
|
use std::borrow::Cow;
|
|
|
|
declare_clippy_lint! {
|
|
/// **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.
|
|
///
|
|
/// **Known problems:** When accessing C, users might want to store pointer
|
|
/// sized objects in `extradata` arguments to save an allocation.
|
|
///
|
|
/// **Example:**
|
|
/// ```ignore
|
|
/// let ptr: *const T = core::intrinsics::transmute('x')
|
|
/// ```
|
|
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
|
|
/// and transmutes that could be a cast.
|
|
///
|
|
/// **Why is this bad?** Readability. The code tricks people into thinking that
|
|
/// something complex is going on.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust,ignore
|
|
/// core::intrinsics::transmute(t); // where the result type is the same as `t`'s
|
|
/// ```
|
|
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.
|
|
///
|
|
/// **Why is this bad?** Readability. The code tricks people into thinking that
|
|
/// something complex is going on.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
///
|
|
/// ```rust
|
|
/// # let p: *const [i32] = &[];
|
|
/// unsafe { std::mem::transmute::<*const [i32], *const [u16]>(p) };
|
|
/// ```
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// # let p: *const [i32] = &[];
|
|
/// p as *const [u16];
|
|
/// ```
|
|
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`.
|
|
///
|
|
/// **Why is this bad?** It's easy to mistakenly transmute between a type and a
|
|
/// pointer to that type.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust,ignore
|
|
/// core::intrinsics::transmute(t) // where the result type is the same as
|
|
/// // `*t` or `&t`'s
|
|
/// ```
|
|
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.
|
|
///
|
|
/// **Why is this bad?** This can always be rewritten with `&` and `*`.
|
|
///
|
|
/// **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:**
|
|
/// ```rust,ignore
|
|
/// unsafe {
|
|
/// let _: &T = std::mem::transmute(p); // where p: *const T
|
|
/// }
|
|
///
|
|
/// // can be written:
|
|
/// let _: &T = &*p;
|
|
/// ```
|
|
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`.
|
|
///
|
|
/// **Why is this bad?** Not every integer is a Unicode scalar value.
|
|
///
|
|
/// **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,
|
|
/// use [`from_u32_unchecked`] which is as fast as `transmute`
|
|
/// but has a semantically meaningful name.
|
|
/// - You might want to handle `None` returned from [`from_u32`] instead of calling `unwrap`.
|
|
///
|
|
/// [`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:**
|
|
/// ```rust
|
|
/// let x = 1_u32;
|
|
/// unsafe {
|
|
/// let _: char = std::mem::transmute(x); // where x: u32
|
|
/// }
|
|
///
|
|
/// // should be:
|
|
/// let _ = std::char::from_u32(x).unwrap();
|
|
/// ```
|
|
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`.
|
|
///
|
|
/// **Why is this bad?** Not every byte slice is a valid UTF-8 string.
|
|
///
|
|
/// **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,
|
|
/// use [`from_utf8_unchecked`] which is as fast as `transmute`
|
|
/// but has a semantically meaningful name.
|
|
/// - You might want to handle errors returned from [`from_utf8`] instead of calling `unwrap`.
|
|
///
|
|
/// [`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:**
|
|
/// ```rust
|
|
/// let b: &[u8] = &[1_u8, 2_u8];
|
|
/// unsafe {
|
|
/// let _: &str = std::mem::transmute(b); // where b: &[u8]
|
|
/// }
|
|
///
|
|
/// // should be:
|
|
/// let _ = std::str::from_utf8(b).unwrap();
|
|
/// ```
|
|
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`.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let x = 1_u8;
|
|
/// unsafe {
|
|
/// let _: bool = std::mem::transmute(x); // where x: u8
|
|
/// }
|
|
///
|
|
/// // should be:
|
|
/// let _: bool = x != 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.
|
|
///
|
|
/// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `from_bits` is intuitive
|
|
/// and safe.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// unsafe {
|
|
/// let _: f32 = std::mem::transmute(1_u32); // where x: u32
|
|
/// }
|
|
///
|
|
/// // should be:
|
|
/// let _: f32 = f32::from_bits(1_u32);
|
|
/// ```
|
|
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.
|
|
///
|
|
/// **Why is this bad?** Transmutes are dangerous and error-prone, whereas `to_bits` is intuitive
|
|
/// and safe.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// unsafe {
|
|
/// let _: u32 = std::mem::transmute(1f32);
|
|
/// }
|
|
///
|
|
/// // should be:
|
|
/// let _: u32 = 1f32.to_bits();
|
|
/// ```
|
|
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
|
|
/// from a reference to a reference.
|
|
///
|
|
/// **Why is this bad?** Transmutes are dangerous, and these can instead be
|
|
/// written as casts.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// let ptr = &1u32 as *const u32;
|
|
/// unsafe {
|
|
/// // pointer-to-pointer transmute
|
|
/// let _: *const f32 = std::mem::transmute(ptr);
|
|
/// // ref-ref transmute
|
|
/// let _: &f32 = std::mem::transmute(&1u32);
|
|
/// }
|
|
/// // These can be respectively written:
|
|
/// let _ = ptr as *const f32;
|
|
/// let _ = unsafe{ &*(&1u32 as *const u32 as *const f32) };
|
|
/// ```
|
|
pub TRANSMUTE_PTR_TO_PTR,
|
|
complexity,
|
|
"transmutes from a pointer to a pointer / a reference to a reference"
|
|
}
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Checks for transmutes between collections whose
|
|
/// types have different ABI, size or alignment.
|
|
///
|
|
/// **Why is this bad?** This is undefined behavior.
|
|
///
|
|
/// **Known problems:** Currently, we cannot know whether a type is a
|
|
/// collection, so we just lint the ones that come with `std`.
|
|
///
|
|
/// **Example:**
|
|
/// ```rust
|
|
/// // different size, therefore likely out-of-bounds memory access
|
|
/// // You absolutely do not want this in your code!
|
|
/// unsafe {
|
|
/// std::mem::transmute::<_, Vec<u32>>(vec![2_u16])
|
|
/// };
|
|
/// ```
|
|
///
|
|
/// You must always iterate, map and collect the values:
|
|
///
|
|
/// ```rust
|
|
/// vec![2_u16].into_iter().map(u32::from).collect::<Vec<_>>();
|
|
/// ```
|
|
pub UNSOUND_COLLECTION_TRANSMUTE,
|
|
correctness,
|
|
"transmute between collections of layout-incompatible types"
|
|
}
|
|
|
|
declare_lint_pass!(Transmute => [
|
|
CROSSPOINTER_TRANSMUTE,
|
|
TRANSMUTE_PTR_TO_REF,
|
|
TRANSMUTE_PTR_TO_PTR,
|
|
USELESS_TRANSMUTE,
|
|
WRONG_TRANSMUTE,
|
|
TRANSMUTE_INT_TO_CHAR,
|
|
TRANSMUTE_BYTES_TO_STR,
|
|
TRANSMUTE_INT_TO_BOOL,
|
|
TRANSMUTE_INT_TO_FLOAT,
|
|
TRANSMUTE_FLOAT_TO_INT,
|
|
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::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);
|
|
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 to_ty = cx.typeck_results().expr_ty(e);
|
|
|
|
match (&from_ty.kind(), &to_ty.kind()) {
|
|
_ if from_ty == to_ty => span_lint(
|
|
cx,
|
|
USELESS_TRANSMUTE,
|
|
e.span,
|
|
&format!("transmute from a type (`{}`) to itself", from_ty),
|
|
),
|
|
(ty::Ref(_, rty, rty_mutbl), ty::RawPtr(ptr_ty)) => span_lint_and_then(
|
|
cx,
|
|
USELESS_TRANSMUTE,
|
|
e.span,
|
|
"transmute from a reference to a pointer",
|
|
|diag| {
|
|
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
|
|
let rty_and_mut = ty::TypeAndMut {
|
|
ty: rty,
|
|
mutbl: *rty_mutbl,
|
|
};
|
|
|
|
let sugg = if *ptr_ty == rty_and_mut {
|
|
arg.as_ty(to_ty)
|
|
} else {
|
|
arg.as_ty(cx.tcx.mk_ptr(rty_and_mut)).as_ty(to_ty)
|
|
};
|
|
|
|
diag.span_suggestion(e.span, "try", sugg.to_string(), Applicability::Unspecified);
|
|
}
|
|
},
|
|
),
|
|
(ty::Int(_) | ty::Uint(_), ty::RawPtr(_)) => span_lint_and_then(
|
|
cx,
|
|
USELESS_TRANSMUTE,
|
|
e.span,
|
|
"transmute from an integer to a pointer",
|
|
|diag| {
|
|
if let Some(arg) = sugg::Sugg::hir_opt(cx, &args[0]) {
|
|
diag.span_suggestion(
|
|
e.span,
|
|
"try",
|
|
arg.as_ty(&to_ty.to_string()).to_string(),
|
|
Applicability::Unspecified,
|
|
);
|
|
}
|
|
},
|
|
),
|
|
(ty::Float(_) | ty::Char, ty::Ref(..) | ty::RawPtr(_)) => span_lint(
|
|
cx,
|
|
WRONG_TRANSMUTE,
|
|
e.span,
|
|
&format!("transmute from a `{}` to a pointer", from_ty),
|
|
),
|
|
(ty::RawPtr(from_ptr), _) if from_ptr.ty == to_ty => span_lint(
|
|
cx,
|
|
CROSSPOINTER_TRANSMUTE,
|
|
e.span,
|
|
&format!(
|
|
"transmute from a type (`{}`) to the type that it points to (`{}`)",
|
|
from_ty, to_ty
|
|
),
|
|
),
|
|
(_, ty::RawPtr(to_ptr)) if to_ptr.ty == from_ty => span_lint(
|
|
cx,
|
|
CROSSPOINTER_TRANSMUTE,
|
|
e.span,
|
|
&format!(
|
|
"transmute from a type (`{}`) to a pointer to that type (`{}`)",
|
|
from_ty, to_ty
|
|
),
|
|
),
|
|
(ty::RawPtr(from_pty), ty::Ref(_, to_ref_ty, mutbl)) => span_lint_and_then(
|
|
cx,
|
|
TRANSMUTE_PTR_TO_REF,
|
|
e.span,
|
|
&format!(
|
|
"transmute from a pointer type (`{}`) to a reference type \
|
|
(`{}`)",
|
|
from_ty, to_ty
|
|
),
|
|
|diag| {
|
|
let arg = sugg::Sugg::hir(cx, &args[0], "..");
|
|
let (deref, cast) = if *mutbl == Mutability::Mut {
|
|
("&mut *", "*mut")
|
|
} else {
|
|
("&*", "*const")
|
|
};
|
|
|
|
let arg = if from_pty.ty == *to_ref_ty {
|
|
arg
|
|
} else {
|
|
arg.as_ty(&format!("{} {}", cast, get_type_snippet(cx, qpath, to_ref_ty)))
|
|
};
|
|
|
|
diag.span_suggestion(
|
|
e.span,
|
|
"try",
|
|
sugg::make_unop(deref, arg).to_string(),
|
|
Applicability::Unspecified,
|
|
);
|
|
},
|
|
),
|
|
(ty::Int(ast::IntTy::I32) | ty::Uint(ast::UintTy::U32), &ty::Char) => {
|
|
span_lint_and_then(
|
|
cx,
|
|
TRANSMUTE_INT_TO_CHAR,
|
|
e.span,
|
|
&format!("transmute from a `{}` to a `char`", from_ty),
|
|
|diag| {
|
|
let arg = sugg::Sugg::hir(cx, &args[0], "..");
|
|
let arg = if let ty::Int(_) = from_ty.kind() {
|
|
arg.as_ty(ast::UintTy::U32.name_str())
|
|
} else {
|
|
arg
|
|
};
|
|
diag.span_suggestion(
|
|
e.span,
|
|
"consider using",
|
|
format!("std::char::from_u32({}).unwrap()", arg.to_string()),
|
|
Applicability::Unspecified,
|
|
);
|
|
},
|
|
)
|
|
},
|
|
(ty::Ref(_, ty_from, from_mutbl), ty::Ref(_, ty_to, to_mutbl)) => {
|
|
if_chain! {
|
|
if let (&ty::Slice(slice_ty), &ty::Str) = (&ty_from.kind(), &ty_to.kind());
|
|
if let ty::Uint(ast::UintTy::U8) = slice_ty.kind();
|
|
if from_mutbl == to_mutbl;
|
|
then {
|
|
let postfix = if *from_mutbl == Mutability::Mut {
|
|
"_mut"
|
|
} else {
|
|
""
|
|
};
|
|
|
|
span_lint_and_sugg(
|
|
cx,
|
|
TRANSMUTE_BYTES_TO_STR,
|
|
e.span,
|
|
&format!("transmute from a `{}` to a `{}`", from_ty, to_ty),
|
|
"consider using",
|
|
format!(
|
|
"std::str::from_utf8{}({}).unwrap()",
|
|
postfix,
|
|
snippet(cx, args[0].span, ".."),
|
|
),
|
|
Applicability::Unspecified,
|
|
);
|
|
} else {
|
|
if (cx.tcx.erase_regions(&from_ty) != cx.tcx.erase_regions(&to_ty))
|
|
&& !const_context {
|
|
span_lint_and_then(
|
|
cx,
|
|
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]) {
|
|
let ty_from_and_mut = ty::TypeAndMut {
|
|
ty: ty_from,
|
|
mutbl: *from_mutbl
|
|
};
|
|
let ty_to_and_mut = ty::TypeAndMut { ty: ty_to, mutbl: *to_mutbl };
|
|
let sugg_paren = arg
|
|
.as_ty(cx.tcx.mk_ptr(ty_from_and_mut))
|
|
.as_ty(cx.tcx.mk_ptr(ty_to_and_mut));
|
|
let sugg = if *to_mutbl == Mutability::Mut {
|
|
sugg_paren.mut_addr_deref()
|
|
} else {
|
|
sugg_paren.addr_deref()
|
|
};
|
|
diag.span_suggestion(
|
|
e.span,
|
|
"try",
|
|
sugg.to_string(),
|
|
Applicability::Unspecified,
|
|
);
|
|
},
|
|
)
|
|
}
|
|
}
|
|
}
|
|
},
|
|
(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(ast::IntTy::I8) | ty::Uint(ast::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::UnNeg, 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
|
|
};
|
|
|
|
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;
|
|
},
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Gets the snippet of `Bar` in `…::transmute<Foo, &Bar>`. If that snippet is
|
|
/// not available , use
|
|
/// the type's `ToString` implementation. In weird cases it could lead to types
|
|
/// with invalid `'_`
|
|
/// lifetime, but it should be rare.
|
|
fn get_type_snippet(cx: &LateContext<'_>, path: &QPath<'_>, to_ref_ty: Ty<'_>) -> String {
|
|
let seg = last_path_segment(path);
|
|
if_chain! {
|
|
if let Some(ref params) = seg.args;
|
|
if !params.parenthesized;
|
|
if let Some(to_ty) = params.args.iter().filter_map(|arg| match arg {
|
|
GenericArg::Type(ty) => Some(ty),
|
|
_ => None,
|
|
}).nth(1);
|
|
if let TyKind::Rptr(_, ref to_ty) = to_ty.kind;
|
|
then {
|
|
return snippet(cx, to_ty.ty.span, &to_ref_ty.to_string()).to_string();
|
|
}
|
|
}
|
|
|
|
to_ref_ty.to_string()
|
|
}
|
|
|
|
// check if the component types of the transmuted collection and the result have different ABI,
|
|
// size or alignment
|
|
fn is_layout_incompatible<'tcx>(cx: &LateContext<'tcx>, from: Ty<'tcx>, to: Ty<'tcx>) -> bool {
|
|
let empty_param_env = ty::ParamEnv::empty();
|
|
// check if `from` and `to` are normalizable to avoid ICE (#4968)
|
|
if !(is_normalizable(cx, empty_param_env, from) && is_normalizable(cx, empty_param_env, to)) {
|
|
return false;
|
|
}
|
|
let from_ty_layout = cx.tcx.layout_of(empty_param_env.and(from));
|
|
let to_ty_layout = cx.tcx.layout_of(empty_param_env.and(to));
|
|
if let (Ok(from_layout), Ok(to_layout)) = (from_ty_layout, to_ty_layout) {
|
|
from_layout.size != to_layout.size || from_layout.align != to_layout.align || from_layout.abi != to_layout.abi
|
|
} else {
|
|
// no idea about layout, so don't lint
|
|
false
|
|
}
|
|
}
|
|
|
|
/// Check if the type conversion can be expressed as a pointer cast, instead of
|
|
/// a transmute. In certain cases, including some invalid casts from array
|
|
/// references to pointers, this may cause additional errors to be emitted and/or
|
|
/// ICE error messages. This function will panic if that occurs.
|
|
fn can_be_expressed_as_pointer_cast<'tcx>(
|
|
cx: &LateContext<'tcx>,
|
|
e: &'tcx Expr<'_>,
|
|
from_ty: Ty<'tcx>,
|
|
to_ty: Ty<'tcx>,
|
|
) -> bool {
|
|
use CastKind::{AddrPtrCast, ArrayPtrCast, FnPtrAddrCast, FnPtrPtrCast, PtrAddrCast, PtrPtrCast};
|
|
matches!(
|
|
check_cast(cx, e, from_ty, to_ty),
|
|
Some(PtrPtrCast | PtrAddrCast | AddrPtrCast | ArrayPtrCast | FnPtrPtrCast | FnPtrAddrCast)
|
|
)
|
|
}
|
|
|
|
/// If a cast from `from_ty` to `to_ty` is valid, returns an Ok containing the kind of
|
|
/// the cast. In certain cases, including some invalid casts from array references
|
|
/// to pointers, this may cause additional errors to be emitted and/or ICE error
|
|
/// messages. This function will panic if that occurs.
|
|
fn check_cast<'tcx>(cx: &LateContext<'tcx>, e: &'tcx Expr<'_>, from_ty: Ty<'tcx>, to_ty: Ty<'tcx>) -> Option<CastKind> {
|
|
let hir_id = e.hir_id;
|
|
let local_def_id = hir_id.owner;
|
|
|
|
Inherited::build(cx.tcx, local_def_id).enter(|inherited| {
|
|
let fn_ctxt = FnCtxt::new(&inherited, cx.param_env, hir_id);
|
|
|
|
// If we already have errors, we can't be sure we can pointer cast.
|
|
assert!(
|
|
!fn_ctxt.errors_reported_since_creation(),
|
|
"Newly created FnCtxt contained errors"
|
|
);
|
|
|
|
if let Ok(check) = CastCheck::new(
|
|
&fn_ctxt, e, from_ty, to_ty,
|
|
// We won't show any error to the user, so we don't care what the span is here.
|
|
DUMMY_SP, DUMMY_SP,
|
|
) {
|
|
let res = check.do_check(&fn_ctxt);
|
|
|
|
// do_check's documentation says that it might return Ok and create
|
|
// errors in the fcx instead of returing Err in some cases. Those cases
|
|
// should be filtered out before getting here.
|
|
assert!(
|
|
!fn_ctxt.errors_reported_since_creation(),
|
|
"`fn_ctxt` contained errors after cast check!"
|
|
);
|
|
|
|
res.ok()
|
|
} else {
|
|
None
|
|
}
|
|
})
|
|
}
|