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use crate::{
fluent_generated as fluent,
lints::{
AtomicOrderingFence, AtomicOrderingLoad, AtomicOrderingStore, ImproperCTypes,
InvalidAtomicOrderingDiag, OnlyCastu8ToChar, OverflowingBinHex, OverflowingBinHexSign,
OverflowingBinHexSub, OverflowingInt, OverflowingIntHelp, OverflowingLiteral,
OverflowingUInt, RangeEndpointOutOfRange, UnusedComparisons, UseInclusiveRange,
VariantSizeDifferencesDiag,
},
};
use crate::{LateContext, LateLintPass, LintContext};
use rustc_ast as ast;
use rustc_attr as attr;
use rustc_data_structures::fx::FxHashSet;
use rustc_errors::DiagnosticMessage;
use rustc_hir as hir;
use rustc_hir::{is_range_literal, Expr, ExprKind, Node};
use rustc_middle::ty::layout::{IntegerExt, LayoutOf, SizeSkeleton};
use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::{
self, AdtKind, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt,
};
use rustc_span::def_id::LocalDefId;
use rustc_span::source_map;
use rustc_span::symbol::sym;
use rustc_span::{Span, Symbol};
use rustc_target::abi::{Abi, Size, WrappingRange};
use rustc_target::abi::{Integer, TagEncoding, Variants};
use rustc_target::spec::abi::Abi as SpecAbi;
use std::iter;
use std::ops::ControlFlow;
declare_lint! {
/// The `unused_comparisons` lint detects comparisons made useless by
/// limits of the types involved.
///
/// ### Example
///
/// ```rust
/// fn foo(x: u8) {
/// x >= 0;
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// A useless comparison may indicate a mistake, and should be fixed or
/// removed.
UNUSED_COMPARISONS,
Warn,
"comparisons made useless by limits of the types involved"
}
declare_lint! {
/// The `overflowing_literals` lint detects literal out of range for its
/// type.
///
/// ### Example
///
/// ```rust,compile_fail
/// let x: u8 = 1000;
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// It is usually a mistake to use a literal that overflows the type where
/// it is used. Either use a literal that is within range, or change the
/// type to be within the range of the literal.
OVERFLOWING_LITERALS,
Deny,
"literal out of range for its type"
}
declare_lint! {
/// The `variant_size_differences` lint detects enums with widely varying
/// variant sizes.
///
/// ### Example
///
/// ```rust,compile_fail
/// #![deny(variant_size_differences)]
/// enum En {
/// V0(u8),
/// VBig([u8; 1024]),
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// It can be a mistake to add a variant to an enum that is much larger
/// than the other variants, bloating the overall size required for all
/// variants. This can impact performance and memory usage. This is
/// triggered if one variant is more than 3 times larger than the
/// second-largest variant.
///
/// Consider placing the large variant's contents on the heap (for example
/// via [`Box`]) to keep the overall size of the enum itself down.
///
/// This lint is "allow" by default because it can be noisy, and may not be
/// an actual problem. Decisions about this should be guided with
/// profiling and benchmarking.
///
/// [`Box`]: https://doc.rust-lang.org/std/boxed/index.html
VARIANT_SIZE_DIFFERENCES,
Allow,
"detects enums with widely varying variant sizes"
}
#[derive(Copy, Clone)]
pub struct TypeLimits {
/// Id of the last visited negated expression
negated_expr_id: Option<hir::HirId>,
}
impl_lint_pass!(TypeLimits => [UNUSED_COMPARISONS, OVERFLOWING_LITERALS]);
impl TypeLimits {
pub fn new() -> TypeLimits {
TypeLimits { negated_expr_id: None }
}
}
/// Attempts to special-case the overflowing literal lint when it occurs as a range endpoint (`expr..MAX+1`).
/// Returns `true` iff the lint was emitted.
fn lint_overflowing_range_endpoint<'tcx>(
cx: &LateContext<'tcx>,
lit: &hir::Lit,
lit_val: u128,
max: u128,
expr: &'tcx hir::Expr<'tcx>,
ty: &str,
) -> bool {
// Look past casts to support cases like `0..256 as u8`
let (expr, lit_span) = if let Node::Expr(par_expr) = cx.tcx.hir().get(cx.tcx.hir().parent_id(expr.hir_id))
&& let ExprKind::Cast(_, _) = par_expr.kind {
(par_expr, expr.span)
} else {
(expr, expr.span)
};
// We only want to handle exclusive (`..`) ranges,
// which are represented as `ExprKind::Struct`.
let par_id = cx.tcx.hir().parent_id(expr.hir_id);
let Node::ExprField(field) = cx.tcx.hir().get(par_id) else { return false };
let Node::Expr(struct_expr) = cx.tcx.hir().get_parent(field.hir_id) else { return false };
if !is_range_literal(struct_expr) {
return false;
};
let ExprKind::Struct(_, eps, _) = &struct_expr.kind else { return false };
if eps.len() != 2 {
return false;
}
// We can suggest using an inclusive range
// (`..=`) instead only if it is the `end` that is
// overflowing and only by 1.
if !(eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max) {
return false;
};
use rustc_ast::{LitIntType, LitKind};
let suffix = match lit.node {
LitKind::Int(_, LitIntType::Signed(s)) => s.name_str(),
LitKind::Int(_, LitIntType::Unsigned(s)) => s.name_str(),
LitKind::Int(_, LitIntType::Unsuffixed) => "",
_ => bug!(),
};
let sub_sugg = if expr.span.lo() == lit_span.lo() {
let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) else { return false };
UseInclusiveRange::WithoutParen {
sugg: struct_expr.span.shrink_to_lo().to(lit_span.shrink_to_hi()),
start,
literal: lit_val - 1,
suffix,
}
} else {
UseInclusiveRange::WithParen {
eq_sugg: expr.span.shrink_to_lo(),
lit_sugg: lit_span,
literal: lit_val - 1,
suffix,
}
};
cx.emit_spanned_lint(
OVERFLOWING_LITERALS,
struct_expr.span,
RangeEndpointOutOfRange { ty, sub: sub_sugg },
);
// We've just emitted a lint, special cased for `(...)..MAX+1` ranges,
// return `true` so the callers don't also emit a lint
true
}
// For `isize` & `usize`, be conservative with the warnings, so that the
// warnings are consistent between 32- and 64-bit platforms.
fn int_ty_range(int_ty: ty::IntTy) -> (i128, i128) {
match int_ty {
ty::IntTy::Isize => (i64::MIN.into(), i64::MAX.into()),
ty::IntTy::I8 => (i8::MIN.into(), i8::MAX.into()),
ty::IntTy::I16 => (i16::MIN.into(), i16::MAX.into()),
ty::IntTy::I32 => (i32::MIN.into(), i32::MAX.into()),
ty::IntTy::I64 => (i64::MIN.into(), i64::MAX.into()),
ty::IntTy::I128 => (i128::MIN, i128::MAX),
}
}
fn uint_ty_range(uint_ty: ty::UintTy) -> (u128, u128) {
let max = match uint_ty {
ty::UintTy::Usize => u64::MAX.into(),
ty::UintTy::U8 => u8::MAX.into(),
ty::UintTy::U16 => u16::MAX.into(),
ty::UintTy::U32 => u32::MAX.into(),
ty::UintTy::U64 => u64::MAX.into(),
ty::UintTy::U128 => u128::MAX,
};
(0, max)
}
fn get_bin_hex_repr(cx: &LateContext<'_>, lit: &hir::Lit) -> Option<String> {
let src = cx.sess().source_map().span_to_snippet(lit.span).ok()?;
let firstch = src.chars().next()?;
if firstch == '0' {
match src.chars().nth(1) {
Some('x' | 'b') => return Some(src),
_ => return None,
}
}
None
}
fn report_bin_hex_error(
cx: &LateContext<'_>,
expr: &hir::Expr<'_>,
ty: attr::IntType,
size: Size,
repr_str: String,
val: u128,
negative: bool,
) {
let (t, actually) = match ty {
attr::IntType::SignedInt(t) => {
let actually = if negative {
-(size.sign_extend(val) as i128)
} else {
size.sign_extend(val) as i128
};
(t.name_str(), actually.to_string())
}
attr::IntType::UnsignedInt(t) => {
let actually = size.truncate(val);
(t.name_str(), actually.to_string())
}
};
let sign =
if negative { OverflowingBinHexSign::Negative } else { OverflowingBinHexSign::Positive };
let sub = get_type_suggestion(cx.typeck_results().node_type(expr.hir_id), val, negative).map(
|suggestion_ty| {
if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') {
let (sans_suffix, _) = repr_str.split_at(pos);
OverflowingBinHexSub::Suggestion { span: expr.span, suggestion_ty, sans_suffix }
} else {
OverflowingBinHexSub::Help { suggestion_ty }
}
},
);
cx.emit_spanned_lint(
OVERFLOWING_LITERALS,
expr.span,
OverflowingBinHex { ty: t, lit: repr_str.clone(), dec: val, actually, sign, sub },
)
}
// This function finds the next fitting type and generates a suggestion string.
// It searches for fitting types in the following way (`X < Y`):
// - `iX`: if literal fits in `uX` => `uX`, else => `iY`
// - `-iX` => `iY`
// - `uX` => `uY`
//
// No suggestion for: `isize`, `usize`.
fn get_type_suggestion(t: Ty<'_>, val: u128, negative: bool) -> Option<&'static str> {
use ty::IntTy::*;
use ty::UintTy::*;
macro_rules! find_fit {
($ty:expr, $val:expr, $negative:expr,
$($type:ident => [$($utypes:expr),*] => [$($itypes:expr),*]),+) => {
{
let _neg = if negative { 1 } else { 0 };
match $ty {
$($type => {
$(if !negative && val <= uint_ty_range($utypes).1 {
return Some($utypes.name_str())
})*
$(if val <= int_ty_range($itypes).1 as u128 + _neg {
return Some($itypes.name_str())
})*
None
},)+
_ => None
}
}
}
}
match t.kind() {
ty::Int(i) => find_fit!(i, val, negative,
I8 => [U8] => [I16, I32, I64, I128],
I16 => [U16] => [I32, I64, I128],
I32 => [U32] => [I64, I128],
I64 => [U64] => [I128],
I128 => [U128] => []),
ty::Uint(u) => find_fit!(u, val, negative,
U8 => [U8, U16, U32, U64, U128] => [],
U16 => [U16, U32, U64, U128] => [],
U32 => [U32, U64, U128] => [],
U64 => [U64, U128] => [],
U128 => [U128] => []),
_ => None,
}
}
fn lint_int_literal<'tcx>(
cx: &LateContext<'tcx>,
type_limits: &TypeLimits,
e: &'tcx hir::Expr<'tcx>,
lit: &hir::Lit,
t: ty::IntTy,
v: u128,
) {
let int_type = t.normalize(cx.sess().target.pointer_width);
let (min, max) = int_ty_range(int_type);
let max = max as u128;
let negative = type_limits.negated_expr_id == Some(e.hir_id);
// Detect literal value out of range [min, max] inclusive
// avoiding use of -min to prevent overflow/panic
if (negative && v > max + 1) || (!negative && v > max) {
if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
report_bin_hex_error(
cx,
e,
attr::IntType::SignedInt(ty::ast_int_ty(t)),
Integer::from_int_ty(cx, t).size(),
repr_str,
v,
negative,
);
return;
}
if lint_overflowing_range_endpoint(cx, lit, v, max, e, t.name_str()) {
// The overflowing literal lint was emitted by `lint_overflowing_range_endpoint`.
return;
}
let lit = cx
.sess()
.source_map()
.span_to_snippet(lit.span)
.expect("must get snippet from literal");
let help = get_type_suggestion(cx.typeck_results().node_type(e.hir_id), v, negative)
.map(|suggestion_ty| OverflowingIntHelp { suggestion_ty });
cx.emit_spanned_lint(
OVERFLOWING_LITERALS,
e.span,
OverflowingInt { ty: t.name_str(), lit, min, max, help },
);
}
}
fn lint_uint_literal<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx hir::Expr<'tcx>,
lit: &hir::Lit,
t: ty::UintTy,
) {
let uint_type = t.normalize(cx.sess().target.pointer_width);
let (min, max) = uint_ty_range(uint_type);
let lit_val: u128 = match lit.node {
// _v is u8, within range by definition
ast::LitKind::Byte(_v) => return,
ast::LitKind::Int(v, _) => v,
_ => bug!(),
};
if lit_val < min || lit_val > max {
let parent_id = cx.tcx.hir().parent_id(e.hir_id);
if let Node::Expr(par_e) = cx.tcx.hir().get(parent_id) {
match par_e.kind {
hir::ExprKind::Cast(..) => {
if let ty::Char = cx.typeck_results().expr_ty(par_e).kind() {
cx.emit_spanned_lint(
OVERFLOWING_LITERALS,
par_e.span,
OnlyCastu8ToChar { span: par_e.span, literal: lit_val },
);
return;
}
}
_ => {}
}
}
if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, t.name_str()) {
// The overflowing literal lint was emitted by `lint_overflowing_range_endpoint`.
return;
}
if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
report_bin_hex_error(
cx,
e,
attr::IntType::UnsignedInt(ty::ast_uint_ty(t)),
Integer::from_uint_ty(cx, t).size(),
repr_str,
lit_val,
false,
);
return;
}
cx.emit_spanned_lint(
OVERFLOWING_LITERALS,
e.span,
OverflowingUInt {
ty: t.name_str(),
lit: cx
.sess()
.source_map()
.span_to_snippet(lit.span)
.expect("must get snippet from literal"),
min,
max,
},
);
}
}
fn lint_literal<'tcx>(
cx: &LateContext<'tcx>,
type_limits: &TypeLimits,
e: &'tcx hir::Expr<'tcx>,
lit: &hir::Lit,
) {
match *cx.typeck_results().node_type(e.hir_id).kind() {
ty::Int(t) => {
match lit.node {
ast::LitKind::Int(v, ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed) => {
lint_int_literal(cx, type_limits, e, lit, t, v)
}
_ => bug!(),
};
}
ty::Uint(t) => lint_uint_literal(cx, e, lit, t),
ty::Float(t) => {
let is_infinite = match lit.node {
ast::LitKind::Float(v, _) => match t {
ty::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite),
ty::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite),
},
_ => bug!(),
};
if is_infinite == Ok(true) {
cx.emit_spanned_lint(
OVERFLOWING_LITERALS,
e.span,
OverflowingLiteral {
ty: t.name_str(),
lit: cx
.sess()
.source_map()
.span_to_snippet(lit.span)
.expect("must get snippet from literal"),
},
);
}
}
_ => {}
}
}
impl<'tcx> LateLintPass<'tcx> for TypeLimits {
fn check_expr(&mut self, cx: &LateContext<'tcx>, e: &'tcx hir::Expr<'tcx>) {
match e.kind {
hir::ExprKind::Unary(hir::UnOp::Neg, ref expr) => {
// propagate negation, if the negation itself isn't negated
if self.negated_expr_id != Some(e.hir_id) {
self.negated_expr_id = Some(expr.hir_id);
}
}
hir::ExprKind::Binary(binop, ref l, ref r) => {
if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
cx.emit_spanned_lint(UNUSED_COMPARISONS, e.span, UnusedComparisons);
}
}
hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit),
_ => {}
};
fn is_valid<T: PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool {
match binop.node {
hir::BinOpKind::Lt => v > min && v <= max,
hir::BinOpKind::Le => v >= min && v < max,
hir::BinOpKind::Gt => v >= min && v < max,
hir::BinOpKind::Ge => v > min && v <= max,
hir::BinOpKind::Eq | hir::BinOpKind::Ne => v >= min && v <= max,
_ => bug!(),
}
}
fn rev_binop(binop: hir::BinOp) -> hir::BinOp {
source_map::respan(
binop.span,
match binop.node {
hir::BinOpKind::Lt => hir::BinOpKind::Gt,
hir::BinOpKind::Le => hir::BinOpKind::Ge,
hir::BinOpKind::Gt => hir::BinOpKind::Lt,
hir::BinOpKind::Ge => hir::BinOpKind::Le,
_ => return binop,
},
)
}
fn check_limits(
cx: &LateContext<'_>,
binop: hir::BinOp,
l: &hir::Expr<'_>,
r: &hir::Expr<'_>,
) -> bool {
let (lit, expr, swap) = match (&l.kind, &r.kind) {
(&hir::ExprKind::Lit(_), _) => (l, r, true),
(_, &hir::ExprKind::Lit(_)) => (r, l, false),
_ => return true,
};
// Normalize the binop so that the literal is always on the RHS in
// the comparison
let norm_binop = if swap { rev_binop(binop) } else { binop };
match *cx.typeck_results().node_type(expr.hir_id).kind() {
ty::Int(int_ty) => {
let (min, max) = int_ty_range(int_ty);
let lit_val: i128 = match lit.kind {
hir::ExprKind::Lit(ref li) => match li.node {
ast::LitKind::Int(
v,
ast::LitIntType::Signed(_) | ast::LitIntType::Unsuffixed,
) => v as i128,
_ => return true,
},
_ => bug!(),
};
is_valid(norm_binop, lit_val, min, max)
}
ty::Uint(uint_ty) => {
let (min, max): (u128, u128) = uint_ty_range(uint_ty);
let lit_val: u128 = match lit.kind {
hir::ExprKind::Lit(ref li) => match li.node {
ast::LitKind::Int(v, _) => v,
_ => return true,
},
_ => bug!(),
};
is_valid(norm_binop, lit_val, min, max)
}
_ => true,
}
}
fn is_comparison(binop: hir::BinOp) -> bool {
matches!(
binop.node,
hir::BinOpKind::Eq
| hir::BinOpKind::Lt
| hir::BinOpKind::Le
| hir::BinOpKind::Ne
| hir::BinOpKind::Ge
| hir::BinOpKind::Gt
)
}
}
}
declare_lint! {
/// The `improper_ctypes` lint detects incorrect use of types in foreign
/// modules.
///
/// ### Example
///
/// ```rust
/// extern "C" {
/// static STATIC: String;
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// The compiler has several checks to verify that types used in `extern`
/// blocks are safe and follow certain rules to ensure proper
/// compatibility with the foreign interfaces. This lint is issued when it
/// detects a probable mistake in a definition. The lint usually should
/// provide a description of the issue, along with possibly a hint on how
/// to resolve it.
IMPROPER_CTYPES,
Warn,
"proper use of libc types in foreign modules"
}
declare_lint_pass!(ImproperCTypesDeclarations => [IMPROPER_CTYPES]);
declare_lint! {
/// The `improper_ctypes_definitions` lint detects incorrect use of
/// [`extern` function] definitions.
///
/// [`extern` function]: https://doc.rust-lang.org/reference/items/functions.html#extern-function-qualifier
///
/// ### Example
///
/// ```rust
/// # #![allow(unused)]
/// pub extern "C" fn str_type(p: &str) { }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// There are many parameter and return types that may be specified in an
/// `extern` function that are not compatible with the given ABI. This
/// lint is an alert that these types should not be used. The lint usually
/// should provide a description of the issue, along with possibly a hint
/// on how to resolve it.
IMPROPER_CTYPES_DEFINITIONS,
Warn,
"proper use of libc types in foreign item definitions"
}
declare_lint_pass!(ImproperCTypesDefinitions => [IMPROPER_CTYPES_DEFINITIONS]);
#[derive(Clone, Copy)]
pub(crate) enum CItemKind {
Declaration,
Definition,
}
struct ImproperCTypesVisitor<'a, 'tcx> {
cx: &'a LateContext<'tcx>,
mode: CItemKind,
}
enum FfiResult<'tcx> {
FfiSafe,
FfiPhantom(Ty<'tcx>),
FfiUnsafe { ty: Ty<'tcx>, reason: DiagnosticMessage, help: Option<DiagnosticMessage> },
}
pub(crate) fn nonnull_optimization_guaranteed<'tcx>(
tcx: TyCtxt<'tcx>,
def: ty::AdtDef<'tcx>,
) -> bool {
tcx.has_attr(def.did(), sym::rustc_nonnull_optimization_guaranteed)
}
/// `repr(transparent)` structs can have a single non-ZST field, this function returns that
/// field.
pub fn transparent_newtype_field<'a, 'tcx>(
tcx: TyCtxt<'tcx>,
variant: &'a ty::VariantDef,
) -> Option<&'a ty::FieldDef> {
let param_env = tcx.param_env(variant.def_id);
variant.fields.iter().find(|field| {
let field_ty = tcx.type_of(field.did).subst_identity();
let is_zst = tcx.layout_of(param_env.and(field_ty)).is_ok_and(|layout| layout.is_zst());
!is_zst
})
}
/// Is type known to be non-null?
fn ty_is_known_nonnull<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>, mode: CItemKind) -> bool {
let tcx = cx.tcx;
match ty.kind() {
ty::FnPtr(_) => true,
ty::Ref(..) => true,
ty::Adt(def, _) if def.is_box() && matches!(mode, CItemKind::Definition) => true,
ty::Adt(def, substs) if def.repr().transparent() && !def.is_union() => {
let marked_non_null = nonnull_optimization_guaranteed(tcx, *def);
if marked_non_null {
return true;
}
// `UnsafeCell` has its niche hidden.
if def.is_unsafe_cell() {
return false;
}
def.variants()
.iter()
.filter_map(|variant| transparent_newtype_field(cx.tcx, variant))
.any(|field| ty_is_known_nonnull(cx, field.ty(tcx, substs), mode))
}
_ => false,
}
}
/// Given a non-null scalar (or transparent) type `ty`, return the nullable version of that type.
/// If the type passed in was not scalar, returns None.
fn get_nullable_type<'tcx>(cx: &LateContext<'tcx>, ty: Ty<'tcx>) -> Option<Ty<'tcx>> {
let tcx = cx.tcx;
Some(match *ty.kind() {
ty::Adt(field_def, field_substs) => {
let inner_field_ty = {
let mut first_non_zst_ty = field_def
.variants()
.iter()
.filter_map(|v| transparent_newtype_field(cx.tcx, v));
debug_assert_eq!(
first_non_zst_ty.clone().count(),
1,
"Wrong number of fields for transparent type"
);
first_non_zst_ty
.next_back()
.expect("No non-zst fields in transparent type.")
.ty(tcx, field_substs)
};
return get_nullable_type(cx, inner_field_ty);
}
ty::Int(ty) => tcx.mk_mach_int(ty),
ty::Uint(ty) => tcx.mk_mach_uint(ty),
ty::RawPtr(ty_mut) => tcx.mk_ptr(ty_mut),
// As these types are always non-null, the nullable equivalent of
// Option<T> of these types are their raw pointer counterparts.
ty::Ref(_region, ty, mutbl) => tcx.mk_ptr(ty::TypeAndMut { ty, mutbl }),
ty::FnPtr(..) => {
// There is no nullable equivalent for Rust's function pointers -- you
// must use an Option<fn(..) -> _> to represent it.
ty
}
// We should only ever reach this case if ty_is_known_nonnull is extended
// to other types.
ref unhandled => {
debug!(
"get_nullable_type: Unhandled scalar kind: {:?} while checking {:?}",
unhandled, ty
);
return None;
}
})
}
/// Check if this enum can be safely exported based on the "nullable pointer optimization". If it
/// can, return the type that `ty` can be safely converted to, otherwise return `None`.
/// Currently restricted to function pointers, boxes, references, `core::num::NonZero*`,
/// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes.
/// FIXME: This duplicates code in codegen.
pub(crate) fn repr_nullable_ptr<'tcx>(
cx: &LateContext<'tcx>,
ty: Ty<'tcx>,
ckind: CItemKind,
) -> Option<Ty<'tcx>> {
debug!("is_repr_nullable_ptr(cx, ty = {:?})", ty);
if let ty::Adt(ty_def, substs) = ty.kind() {
let field_ty = match &ty_def.variants().raw[..] {
[var_one, var_two] => match (&var_one.fields.raw[..], &var_two.fields.raw[..]) {
([], [field]) | ([field], []) => field.ty(cx.tcx, substs),
_ => return None,
},
_ => return None,
};
if !ty_is_known_nonnull(cx, field_ty, ckind) {
return None;
}
// At this point, the field's type is known to be nonnull and the parent enum is Option-like.
// If the computed size for the field and the enum are different, the nonnull optimization isn't
// being applied (and we've got a problem somewhere).
let compute_size_skeleton = |t| SizeSkeleton::compute(t, cx.tcx, cx.param_env).unwrap();
if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) {
bug!("improper_ctypes: Option nonnull optimization not applied?");
}
// Return the nullable type this Option-like enum can be safely represented with.
let field_ty_abi = &cx.layout_of(field_ty).unwrap().abi;
if let Abi::Scalar(field_ty_scalar) = field_ty_abi {
match field_ty_scalar.valid_range(cx) {
WrappingRange { start: 0, end }
if end == field_ty_scalar.size(&cx.tcx).unsigned_int_max() - 1 =>
{
return Some(get_nullable_type(cx, field_ty).unwrap());
}
WrappingRange { start: 1, .. } => {
return Some(get_nullable_type(cx, field_ty).unwrap());
}
WrappingRange { start, end } => {
unreachable!("Unhandled start and end range: ({}, {})", start, end)
}
};
}
}
None
}
impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
/// Check if the type is array and emit an unsafe type lint.
fn check_for_array_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
if let ty::Array(..) = ty.kind() {
self.emit_ffi_unsafe_type_lint(
ty,
sp,
fluent::lint_improper_ctypes_array_reason,
Some(fluent::lint_improper_ctypes_array_help),
);
true
} else {
false
}
}
/// Checks if the given field's type is "ffi-safe".
fn check_field_type_for_ffi(
&self,
cache: &mut FxHashSet<Ty<'tcx>>,
field: &ty::FieldDef,
substs: SubstsRef<'tcx>,
) -> FfiResult<'tcx> {
let field_ty = field.ty(self.cx.tcx, substs);
if field_ty.has_opaque_types() {
self.check_type_for_ffi(cache, field_ty)
} else {
let field_ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, field_ty);
self.check_type_for_ffi(cache, field_ty)
}
}
/// Checks if the given `VariantDef`'s field types are "ffi-safe".
fn check_variant_for_ffi(
&self,
cache: &mut FxHashSet<Ty<'tcx>>,
ty: Ty<'tcx>,
def: ty::AdtDef<'tcx>,
variant: &ty::VariantDef,
substs: SubstsRef<'tcx>,
) -> FfiResult<'tcx> {
use FfiResult::*;
let transparent_safety = def.repr().transparent().then(|| {
// Can assume that at most one field is not a ZST, so only check
// that field's type for FFI-safety.
if let Some(field) = transparent_newtype_field(self.cx.tcx, variant) {
return self.check_field_type_for_ffi(cache, field, substs);
} else {
// All fields are ZSTs; this means that the type should behave
// like (), which is FFI-unsafe... except if all fields are PhantomData,
// which is tested for below
FfiUnsafe { ty, reason: fluent::lint_improper_ctypes_struct_zst, help: None }
}
});
// We can't completely trust repr(C) markings; make sure the fields are
// actually safe.
let mut all_phantom = !variant.fields.is_empty();
for field in &variant.fields {
match self.check_field_type_for_ffi(cache, &field, substs) {
FfiSafe => {
all_phantom = false;
}
FfiPhantom(..) if !def.repr().transparent() && def.is_enum() => {
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_enum_phantomdata,
help: None,
};
}
FfiPhantom(..) => {}
r => return transparent_safety.unwrap_or(r),
}
}
if all_phantom { FfiPhantom(ty) } else { transparent_safety.unwrap_or(FfiSafe) }
}
/// Checks if the given type is "ffi-safe" (has a stable, well-defined
/// representation which can be exported to C code).
fn check_type_for_ffi(&self, cache: &mut FxHashSet<Ty<'tcx>>, ty: Ty<'tcx>) -> FfiResult<'tcx> {
use FfiResult::*;
let tcx = self.cx.tcx;
// Protect against infinite recursion, for example
// `struct S(*mut S);`.
// FIXME: A recursion limit is necessary as well, for irregular
// recursive types.
if !cache.insert(ty) {
return FfiSafe;
}
match *ty.kind() {
ty::Adt(def, substs) => {
if def.is_box() && matches!(self.mode, CItemKind::Definition) {
if ty.boxed_ty().is_sized(tcx, self.cx.param_env) {
return FfiSafe;
} else {
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_box,
help: None,
};
}
}
if def.is_phantom_data() {
return FfiPhantom(ty);
}
match def.adt_kind() {
AdtKind::Struct | AdtKind::Union => {
if !def.repr().c() && !def.repr().transparent() {
return FfiUnsafe {
ty,
reason: if def.is_struct() {
fluent::lint_improper_ctypes_struct_layout_reason
} else {
fluent::lint_improper_ctypes_union_layout_reason
},
help: if def.is_struct() {
Some(fluent::lint_improper_ctypes_struct_layout_help)
} else {
Some(fluent::lint_improper_ctypes_union_layout_help)
},
};
}
let is_non_exhaustive =
def.non_enum_variant().is_field_list_non_exhaustive();
if is_non_exhaustive && !def.did().is_local() {
return FfiUnsafe {
ty,
reason: if def.is_struct() {
fluent::lint_improper_ctypes_struct_non_exhaustive
} else {
fluent::lint_improper_ctypes_union_non_exhaustive
},
help: None,
};
}
if def.non_enum_variant().fields.is_empty() {
return FfiUnsafe {
ty,
reason: if def.is_struct() {
fluent::lint_improper_ctypes_struct_fieldless_reason
} else {
fluent::lint_improper_ctypes_union_fieldless_reason
},
help: if def.is_struct() {
Some(fluent::lint_improper_ctypes_struct_fieldless_help)
} else {
Some(fluent::lint_improper_ctypes_union_fieldless_help)
},
};
}
self.check_variant_for_ffi(cache, ty, def, def.non_enum_variant(), substs)
}
AdtKind::Enum => {
if def.variants().is_empty() {
// Empty enums are okay... although sort of useless.
return FfiSafe;
}
// Check for a repr() attribute to specify the size of the
// discriminant.
if !def.repr().c() && !def.repr().transparent() && def.repr().int.is_none()
{
// Special-case types like `Option<extern fn()>`.
if repr_nullable_ptr(self.cx, ty, self.mode).is_none() {
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_enum_repr_reason,
help: Some(fluent::lint_improper_ctypes_enum_repr_help),
};
}
}
if def.is_variant_list_non_exhaustive() && !def.did().is_local() {
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_non_exhaustive,
help: None,
};
}
// Check the contained variants.
for variant in def.variants() {
let is_non_exhaustive = variant.is_field_list_non_exhaustive();
if is_non_exhaustive && !variant.def_id.is_local() {
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_non_exhaustive_variant,
help: None,
};
}
match self.check_variant_for_ffi(cache, ty, def, variant, substs) {
FfiSafe => (),
r => return r,
}
}
FfiSafe
}
}
}
ty::Char => FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_char_reason,
help: Some(fluent::lint_improper_ctypes_char_help),
},
ty::Int(ty::IntTy::I128) | ty::Uint(ty::UintTy::U128) => {
FfiUnsafe { ty, reason: fluent::lint_improper_ctypes_128bit, help: None }
}
// Primitive types with a stable representation.
ty::Bool | ty::Int(..) | ty::Uint(..) | ty::Float(..) | ty::Never => FfiSafe,
ty::Slice(_) => FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_slice_reason,
help: Some(fluent::lint_improper_ctypes_slice_help),
},
ty::Dynamic(..) => {
FfiUnsafe { ty, reason: fluent::lint_improper_ctypes_dyn, help: None }
}
ty::Str => FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_str_reason,
help: Some(fluent::lint_improper_ctypes_str_help),
},
ty::Tuple(..) => FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_tuple_reason,
help: Some(fluent::lint_improper_ctypes_tuple_help),
},
ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _)
if {
matches!(self.mode, CItemKind::Definition)
&& ty.is_sized(self.cx.tcx, self.cx.param_env)
} =>
{
FfiSafe
}
ty::RawPtr(ty::TypeAndMut { ty, .. })
if match ty.kind() {
ty::Tuple(tuple) => tuple.is_empty(),
_ => false,
} =>
{
FfiSafe
}
ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
self.check_type_for_ffi(cache, ty)
}
ty::Array(inner_ty, _) => self.check_type_for_ffi(cache, inner_ty),
ty::FnPtr(sig) => {
if self.is_internal_abi(sig.abi()) {
return FfiUnsafe {
ty,
reason: fluent::lint_improper_ctypes_fnptr_reason,
help: Some(fluent::lint_improper_ctypes_fnptr_help),
};
}
let sig = tcx.erase_late_bound_regions(sig);
if !sig.output().is_unit() {
let r = self.check_type_for_ffi(cache, sig.output());
match r {
FfiSafe => {}
_ => {
return r;
}
}
}
for arg in sig.inputs() {
let r = self.check_type_for_ffi(cache, *arg);
match r {
FfiSafe => {}
_ => {
return r;
}
}
}
FfiSafe
}
ty::Foreign(..) => FfiSafe,
// While opaque types are checked for earlier, if a projection in a struct field
// normalizes to an opaque type, then it will reach this branch.
ty::Alias(ty::Opaque, ..) => {
FfiUnsafe { ty, reason: fluent::lint_improper_ctypes_opaque, help: None }
}
// `extern "C" fn` functions can have type parameters, which may or may not be FFI-safe,
// so they are currently ignored for the purposes of this lint.
ty::Param(..) | ty::Alias(ty::Projection | ty::Inherent, ..)
if matches!(self.mode, CItemKind::Definition) =>
{
FfiSafe
}
ty::Param(..)
| ty::Alias(ty::Projection | ty::Inherent, ..)
| ty::Infer(..)
| ty::Bound(..)
| ty::Error(_)
| ty::Closure(..)
| ty::Generator(..)
| ty::GeneratorWitness(..)
| ty::GeneratorWitnessMIR(..)
| ty::Placeholder(..)
| ty::FnDef(..) => bug!("unexpected type in foreign function: {:?}", ty),
}
}
fn emit_ffi_unsafe_type_lint(
&mut self,
ty: Ty<'tcx>,
sp: Span,
note: DiagnosticMessage,
help: Option<DiagnosticMessage>,
) {
let lint = match self.mode {
CItemKind::Declaration => IMPROPER_CTYPES,
CItemKind::Definition => IMPROPER_CTYPES_DEFINITIONS,
};
let desc = match self.mode {
CItemKind::Declaration => "block",
CItemKind::Definition => "fn",
};
let span_note = if let ty::Adt(def, _) = ty.kind()
&& let Some(sp) = self.cx.tcx.hir().span_if_local(def.did()) {
Some(sp)
} else {
None
};
self.cx.emit_spanned_lint(
lint,
sp,
ImproperCTypes { ty, desc, label: sp, help, note, span_note },
);
}
fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
struct ProhibitOpaqueTypes;
impl<'tcx> ty::visit::TypeVisitor<TyCtxt<'tcx>> for ProhibitOpaqueTypes {
type BreakTy = Ty<'tcx>;
fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
if !ty.has_opaque_types() {
return ControlFlow::Continue(());
}
if let ty::Alias(ty::Opaque, ..) = ty.kind() {
ControlFlow::Break(ty)
} else {
ty.super_visit_with(self)
}
}
}
if let Some(ty) = self
.cx
.tcx
.normalize_erasing_regions(self.cx.param_env, ty)
.visit_with(&mut ProhibitOpaqueTypes)
.break_value()
{
self.emit_ffi_unsafe_type_lint(ty, sp, fluent::lint_improper_ctypes_opaque, None);
true
} else {
false
}
}
fn check_type_for_ffi_and_report_errors(
&mut self,
sp: Span,
ty: Ty<'tcx>,
is_static: bool,
is_return_type: bool,
) {
// We have to check for opaque types before `normalize_erasing_regions`,
// which will replace opaque types with their underlying concrete type.
if self.check_for_opaque_ty(sp, ty) {
// We've already emitted an error due to an opaque type.
return;
}
// it is only OK to use this function because extern fns cannot have
// any generic types right now:
let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty);
// C doesn't really support passing arrays by value - the only way to pass an array by value
// is through a struct. So, first test that the top level isn't an array, and then
// recursively check the types inside.
if !is_static && self.check_for_array_ty(sp, ty) {
return;
}
// Don't report FFI errors for unit return types. This check exists here, and not in
// `check_foreign_fn` (where it would make more sense) so that normalization has definitely
// happened.
if is_return_type && ty.is_unit() {
return;
}
match self.check_type_for_ffi(&mut FxHashSet::default(), ty) {
FfiResult::FfiSafe => {}
FfiResult::FfiPhantom(ty) => {
self.emit_ffi_unsafe_type_lint(
ty,
sp,
fluent::lint_improper_ctypes_only_phantomdata,
None,
);
}
// If `ty` is a `repr(transparent)` newtype, and the non-zero-sized type is a generic
// argument, which after substitution, is `()`, then this branch can be hit.
FfiResult::FfiUnsafe { ty, .. } if is_return_type && ty.is_unit() => {}
FfiResult::FfiUnsafe { ty, reason, help } => {
self.emit_ffi_unsafe_type_lint(ty, sp, reason, help);
}
}
}
fn check_foreign_fn(&mut self, def_id: LocalDefId, decl: &hir::FnDecl<'_>) {
let sig = self.cx.tcx.fn_sig(def_id).subst_identity();
let sig = self.cx.tcx.erase_late_bound_regions(sig);
for (input_ty, input_hir) in iter::zip(sig.inputs(), decl.inputs) {
self.check_type_for_ffi_and_report_errors(input_hir.span, *input_ty, false, false);
}
if let hir::FnRetTy::Return(ref ret_hir) = decl.output {
let ret_ty = sig.output();
self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty, false, true);
}
}
fn check_foreign_static(&mut self, id: hir::OwnerId, span: Span) {
let ty = self.cx.tcx.type_of(id).subst_identity();
self.check_type_for_ffi_and_report_errors(span, ty, true, false);
}
fn is_internal_abi(&self, abi: SpecAbi) -> bool {
matches!(
abi,
SpecAbi::Rust | SpecAbi::RustCall | SpecAbi::RustIntrinsic | SpecAbi::PlatformIntrinsic
)
}
}
impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDeclarations {
fn check_foreign_item(&mut self, cx: &LateContext<'_>, it: &hir::ForeignItem<'_>) {
let mut vis = ImproperCTypesVisitor { cx, mode: CItemKind::Declaration };
let abi = cx.tcx.hir().get_foreign_abi(it.hir_id());
if !vis.is_internal_abi(abi) {
match it.kind {
hir::ForeignItemKind::Fn(ref decl, _, _) => {
vis.check_foreign_fn(it.owner_id.def_id, decl);
}
hir::ForeignItemKind::Static(ref ty, _) => {
vis.check_foreign_static(it.owner_id, ty.span);
}
hir::ForeignItemKind::Type => (),
}
}
}
}
impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDefinitions {
fn check_fn(
&mut self,
cx: &LateContext<'tcx>,
kind: hir::intravisit::FnKind<'tcx>,
decl: &'tcx hir::FnDecl<'_>,
_: &'tcx hir::Body<'_>,
_: Span,
id: LocalDefId,
) {
use hir::intravisit::FnKind;
let abi = match kind {
FnKind::ItemFn(_, _, header, ..) => header.abi,
FnKind::Method(_, sig, ..) => sig.header.abi,
_ => return,
};
let mut vis = ImproperCTypesVisitor { cx, mode: CItemKind::Definition };
if !vis.is_internal_abi(abi) {
vis.check_foreign_fn(id, decl);
}
}
}
declare_lint_pass!(VariantSizeDifferences => [VARIANT_SIZE_DIFFERENCES]);
impl<'tcx> LateLintPass<'tcx> for VariantSizeDifferences {
fn check_item(&mut self, cx: &LateContext<'_>, it: &hir::Item<'_>) {
if let hir::ItemKind::Enum(ref enum_definition, _) = it.kind {
let t = cx.tcx.type_of(it.owner_id).subst_identity();
let ty = cx.tcx.erase_regions(t);
let Ok(layout) = cx.layout_of(ty) else { return };
let Variants::Multiple {
tag_encoding: TagEncoding::Direct, tag, ref variants, ..
} = &layout.variants else {
return
};
let tag_size = tag.size(&cx.tcx).bytes();
debug!(
"enum `{}` is {} bytes large with layout:\n{:#?}",
t,
layout.size.bytes(),
layout
);
let (largest, slargest, largest_index) = iter::zip(enum_definition.variants, variants)
.map(|(variant, variant_layout)| {
// Subtract the size of the enum tag.
let bytes = variant_layout.size.bytes().saturating_sub(tag_size);
debug!("- variant `{}` is {} bytes large", variant.ident, bytes);
bytes
})
.enumerate()
.fold((0, 0, 0), |(l, s, li), (idx, size)| {
if size > l {
(size, l, idx)
} else if size > s {
(l, size, li)
} else {
(l, s, li)
}
});
// We only warn if the largest variant is at least thrice as large as
// the second-largest.
if largest > slargest * 3 && slargest > 0 {
cx.emit_spanned_lint(
VARIANT_SIZE_DIFFERENCES,
enum_definition.variants[largest_index].span,
VariantSizeDifferencesDiag { largest },
);
}
}
}
}
declare_lint! {
/// The `invalid_atomic_ordering` lint detects passing an `Ordering`
/// to an atomic operation that does not support that ordering.
///
/// ### Example
///
/// ```rust,compile_fail
/// # use core::sync::atomic::{AtomicU8, Ordering};
/// let atom = AtomicU8::new(0);
/// let value = atom.load(Ordering::Release);
/// # let _ = value;
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// Some atomic operations are only supported for a subset of the
/// `atomic::Ordering` variants. Passing an unsupported variant will cause
/// an unconditional panic at runtime, which is detected by this lint.
///
/// This lint will trigger in the following cases: (where `AtomicType` is an
/// atomic type from `core::sync::atomic`, such as `AtomicBool`,
/// `AtomicPtr`, `AtomicUsize`, or any of the other integer atomics).
///
/// - Passing `Ordering::Acquire` or `Ordering::AcqRel` to
/// `AtomicType::store`.
///
/// - Passing `Ordering::Release` or `Ordering::AcqRel` to
/// `AtomicType::load`.
///
/// - Passing `Ordering::Relaxed` to `core::sync::atomic::fence` or
/// `core::sync::atomic::compiler_fence`.
///
/// - Passing `Ordering::Release` or `Ordering::AcqRel` as the failure
/// ordering for any of `AtomicType::compare_exchange`,
/// `AtomicType::compare_exchange_weak`, or `AtomicType::fetch_update`.
INVALID_ATOMIC_ORDERING,
Deny,
"usage of invalid atomic ordering in atomic operations and memory fences"
}
declare_lint_pass!(InvalidAtomicOrdering => [INVALID_ATOMIC_ORDERING]);
impl InvalidAtomicOrdering {
fn inherent_atomic_method_call<'hir>(
cx: &LateContext<'_>,
expr: &Expr<'hir>,
recognized_names: &[Symbol], // used for fast path calculation
) -> Option<(Symbol, &'hir [Expr<'hir>])> {
const ATOMIC_TYPES: &[Symbol] = &[
sym::AtomicBool,
sym::AtomicPtr,
sym::AtomicUsize,
sym::AtomicU8,
sym::AtomicU16,
sym::AtomicU32,
sym::AtomicU64,
sym::AtomicU128,
sym::AtomicIsize,
sym::AtomicI8,
sym::AtomicI16,
sym::AtomicI32,
sym::AtomicI64,
sym::AtomicI128,
];
if let ExprKind::MethodCall(ref method_path, _, args, _) = &expr.kind
&& recognized_names.contains(&method_path.ident.name)
&& let Some(m_def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id)
&& let Some(impl_did) = cx.tcx.impl_of_method(m_def_id)
&& let Some(adt) = cx.tcx.type_of(impl_did).subst_identity().ty_adt_def()
// skip extension traits, only lint functions from the standard library
&& cx.tcx.trait_id_of_impl(impl_did).is_none()
&& let parent = cx.tcx.parent(adt.did())
&& cx.tcx.is_diagnostic_item(sym::atomic_mod, parent)
&& ATOMIC_TYPES.contains(&cx.tcx.item_name(adt.did()))
{
return Some((method_path.ident.name, args));
}
None
}
fn match_ordering(cx: &LateContext<'_>, ord_arg: &Expr<'_>) -> Option<Symbol> {
let ExprKind::Path(ref ord_qpath) = ord_arg.kind else { return None };
let did = cx.qpath_res(ord_qpath, ord_arg.hir_id).opt_def_id()?;
let tcx = cx.tcx;
let atomic_ordering = tcx.get_diagnostic_item(sym::Ordering);
let name = tcx.item_name(did);
let parent = tcx.parent(did);
[sym::Relaxed, sym::Release, sym::Acquire, sym::AcqRel, sym::SeqCst].into_iter().find(
|&ordering| {
name == ordering
&& (Some(parent) == atomic_ordering
// needed in case this is a ctor, not a variant
|| tcx.opt_parent(parent) == atomic_ordering)
},
)
}
fn check_atomic_load_store(cx: &LateContext<'_>, expr: &Expr<'_>) {
if let Some((method, args)) = Self::inherent_atomic_method_call(cx, expr, &[sym::load, sym::store])
&& let Some((ordering_arg, invalid_ordering)) = match method {
sym::load => Some((&args[0], sym::Release)),
sym::store => Some((&args[1], sym::Acquire)),
_ => None,
}
&& let Some(ordering) = Self::match_ordering(cx, ordering_arg)
&& (ordering == invalid_ordering || ordering == sym::AcqRel)
{
if method == sym::load {
cx.emit_spanned_lint(INVALID_ATOMIC_ORDERING, ordering_arg.span, AtomicOrderingLoad);
} else {
cx.emit_spanned_lint(INVALID_ATOMIC_ORDERING, ordering_arg.span, AtomicOrderingStore);
};
}
}
fn check_memory_fence(cx: &LateContext<'_>, expr: &Expr<'_>) {
if let ExprKind::Call(ref func, ref args) = expr.kind
&& let ExprKind::Path(ref func_qpath) = func.kind
&& let Some(def_id) = cx.qpath_res(func_qpath, func.hir_id).opt_def_id()
&& matches!(cx.tcx.get_diagnostic_name(def_id), Some(sym::fence | sym::compiler_fence))
&& Self::match_ordering(cx, &args[0]) == Some(sym::Relaxed)
{
cx.emit_spanned_lint(INVALID_ATOMIC_ORDERING, args[0].span, AtomicOrderingFence);
}
}
fn check_atomic_compare_exchange(cx: &LateContext<'_>, expr: &Expr<'_>) {
let Some((method, args)) = Self::inherent_atomic_method_call(cx, expr, &[sym::fetch_update, sym::compare_exchange, sym::compare_exchange_weak])
else {return };
let fail_order_arg = match method {
sym::fetch_update => &args[1],
sym::compare_exchange | sym::compare_exchange_weak => &args[3],
_ => return,
};
let Some(fail_ordering) = Self::match_ordering(cx, fail_order_arg) else { return };
if matches!(fail_ordering, sym::Release | sym::AcqRel) {
cx.emit_spanned_lint(
INVALID_ATOMIC_ORDERING,
fail_order_arg.span,
InvalidAtomicOrderingDiag { method, fail_order_arg_span: fail_order_arg.span },
);
}
}
}
impl<'tcx> LateLintPass<'tcx> for InvalidAtomicOrdering {
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
Self::check_atomic_load_store(cx, expr);
Self::check_memory_fence(cx, expr);
Self::check_atomic_compare_exchange(cx, expr);
}
}