1 #![allow(non_snake_case)]
3 use crate::{LateContext, LateLintPass, LintContext};
4 use rustc::mir::interpret::{sign_extend, truncate};
5 use rustc::ty::layout::{self, IntegerExt, LayoutOf, SizeSkeleton, VariantIdx};
6 use rustc::ty::subst::SubstsRef;
7 use rustc::ty::{self, AdtKind, ParamEnv, Ty, TyCtxt};
8 use rustc_data_structures::fx::FxHashSet;
9 use rustc_errors::Applicability;
11 use rustc_hir::def_id::DefId;
12 use rustc_hir::{is_range_literal, ExprKind, Node};
13 use rustc_index::vec::Idx;
14 use rustc_span::source_map;
15 use rustc_span::symbol::sym;
17 use rustc_target::spec::abi::Abi;
18 use syntax::{ast, attr};
22 use std::{f32, f64, i16, i32, i64, i8, u16, u32, u64, u8};
27 "comparisons made useless by limits of the types involved"
33 "literal out of range for its type"
37 VARIANT_SIZE_DIFFERENCES,
39 "detects enums with widely varying variant sizes"
42 #[derive(Copy, Clone)]
43 pub struct TypeLimits {
44 /// Id of the last visited negated expression
45 negated_expr_id: hir::HirId,
48 impl_lint_pass!(TypeLimits => [UNUSED_COMPARISONS, OVERFLOWING_LITERALS]);
51 pub fn new() -> TypeLimits {
52 TypeLimits { negated_expr_id: hir::DUMMY_HIR_ID }
56 /// Attempts to special-case the overflowing literal lint when it occurs as a range endpoint.
57 /// Returns `true` iff the lint was overridden.
58 fn lint_overflowing_range_endpoint<'a, 'tcx>(
59 cx: &LateContext<'a, 'tcx>,
63 expr: &'tcx hir::Expr<'tcx>,
64 parent_expr: &'tcx hir::Expr<'tcx>,
67 // We only want to handle exclusive (`..`) ranges,
68 // which are represented as `ExprKind::Struct`.
69 if let ExprKind::Struct(_, eps, _) = &parent_expr.kind {
73 // We can suggest using an inclusive range
74 // (`..=`) instead only if it is the `end` that is
75 // overflowing and only by 1.
76 if eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max {
77 let mut err = cx.struct_span_lint(
80 &format!("range endpoint is out of range for `{}`", ty),
82 if let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) {
83 use ast::{LitIntType, LitKind};
84 // We need to preserve the literal's suffix,
85 // as it may determine typing information.
86 let suffix = match lit.node {
87 LitKind::Int(_, LitIntType::Signed(s)) => format!("{}", s.name_str()),
88 LitKind::Int(_, LitIntType::Unsigned(s)) => format!("{}", s.name_str()),
89 LitKind::Int(_, LitIntType::Unsuffixed) => "".to_owned(),
92 let suggestion = format!("{}..={}{}", start, lit_val - 1, suffix);
95 &"use an inclusive range instead",
97 Applicability::MachineApplicable,
108 // For `isize` & `usize`, be conservative with the warnings, so that the
109 // warnings are consistent between 32- and 64-bit platforms.
110 fn int_ty_range(int_ty: ast::IntTy) -> (i128, i128) {
112 ast::IntTy::Isize => (i64::min_value() as i128, i64::max_value() as i128),
113 ast::IntTy::I8 => (i8::min_value() as i64 as i128, i8::max_value() as i128),
114 ast::IntTy::I16 => (i16::min_value() as i64 as i128, i16::max_value() as i128),
115 ast::IntTy::I32 => (i32::min_value() as i64 as i128, i32::max_value() as i128),
116 ast::IntTy::I64 => (i64::min_value() as i128, i64::max_value() as i128),
117 ast::IntTy::I128 => (i128::min_value() as i128, i128::max_value()),
121 fn uint_ty_range(uint_ty: ast::UintTy) -> (u128, u128) {
123 ast::UintTy::Usize => (u64::min_value() as u128, u64::max_value() as u128),
124 ast::UintTy::U8 => (u8::min_value() as u128, u8::max_value() as u128),
125 ast::UintTy::U16 => (u16::min_value() as u128, u16::max_value() as u128),
126 ast::UintTy::U32 => (u32::min_value() as u128, u32::max_value() as u128),
127 ast::UintTy::U64 => (u64::min_value() as u128, u64::max_value() as u128),
128 ast::UintTy::U128 => (u128::min_value(), u128::max_value()),
132 fn get_bin_hex_repr(cx: &LateContext<'_, '_>, lit: &hir::Lit) -> Option<String> {
133 let src = cx.sess().source_map().span_to_snippet(lit.span).ok()?;
134 let firstch = src.chars().next()?;
137 match src.chars().nth(1) {
138 Some('x') | Some('b') => return Some(src),
146 fn report_bin_hex_error(
147 cx: &LateContext<'_, '_>,
148 expr: &hir::Expr<'_>,
154 let size = layout::Integer::from_attr(&cx.tcx, ty).size();
155 let (t, actually) = match ty {
156 attr::IntType::SignedInt(t) => {
157 let actually = sign_extend(val, size) as i128;
158 (t.name_str(), actually.to_string())
160 attr::IntType::UnsignedInt(t) => {
161 let actually = truncate(val, size);
162 (t.name_str(), actually.to_string())
165 let mut err = cx.struct_span_lint(
166 OVERFLOWING_LITERALS,
168 &format!("literal out of range for {}", t),
171 "the literal `{}` (decimal `{}`) does not fit into \
172 an `{}` and will become `{}{}`",
173 repr_str, val, t, actually, t
175 if let Some(sugg_ty) = get_type_suggestion(&cx.tables.node_type(expr.hir_id), val, negative) {
176 if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') {
177 let (sans_suffix, _) = repr_str.split_at(pos);
180 &format!("consider using `{}` instead", sugg_ty),
181 format!("{}{}", sans_suffix, sugg_ty),
182 Applicability::MachineApplicable,
185 err.help(&format!("consider using `{}` instead", sugg_ty));
192 // This function finds the next fitting type and generates a suggestion string.
193 // It searches for fitting types in the following way (`X < Y`):
194 // - `iX`: if literal fits in `uX` => `uX`, else => `iY`
198 // No suggestion for: `isize`, `usize`.
199 fn get_type_suggestion(t: Ty<'_>, val: u128, negative: bool) -> Option<&'static str> {
200 use syntax::ast::IntTy::*;
201 use syntax::ast::UintTy::*;
202 macro_rules! find_fit {
203 ($ty:expr, $val:expr, $negative:expr,
204 $($type:ident => [$($utypes:expr),*] => [$($itypes:expr),*]),+) => {
206 let _neg = if negative { 1 } else { 0 };
209 $(if !negative && val <= uint_ty_range($utypes).1 {
210 return Some($utypes.name_str())
212 $(if val <= int_ty_range($itypes).1 as u128 + _neg {
213 return Some($itypes.name_str())
223 ty::Int(i) => find_fit!(i, val, negative,
224 I8 => [U8] => [I16, I32, I64, I128],
225 I16 => [U16] => [I32, I64, I128],
226 I32 => [U32] => [I64, I128],
227 I64 => [U64] => [I128],
228 I128 => [U128] => []),
229 ty::Uint(u) => find_fit!(u, val, negative,
230 U8 => [U8, U16, U32, U64, U128] => [],
231 U16 => [U16, U32, U64, U128] => [],
232 U32 => [U32, U64, U128] => [],
233 U64 => [U64, U128] => [],
234 U128 => [U128] => []),
239 fn lint_int_literal<'a, 'tcx>(
240 cx: &LateContext<'a, 'tcx>,
241 type_limits: &TypeLimits,
242 e: &'tcx hir::Expr<'tcx>,
247 let int_type = t.normalize(cx.sess().target.ptr_width);
248 let (_, max) = int_ty_range(int_type);
249 let max = max as u128;
250 let negative = type_limits.negated_expr_id == e.hir_id;
252 // Detect literal value out of range [min, max] inclusive
253 // avoiding use of -min to prevent overflow/panic
254 if (negative && v > max + 1) || (!negative && v > max) {
255 if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
256 report_bin_hex_error(cx, e, attr::IntType::SignedInt(t), repr_str, v, negative);
260 let par_id = cx.tcx.hir().get_parent_node(e.hir_id);
261 if let Node::Expr(par_e) = cx.tcx.hir().get(par_id) {
262 if let hir::ExprKind::Struct(..) = par_e.kind {
263 if is_range_literal(cx.sess().source_map(), par_e)
264 && lint_overflowing_range_endpoint(cx, lit, v, max, e, par_e, t.name_str())
266 // The overflowing literal lint was overridden.
273 OVERFLOWING_LITERALS,
275 &format!("literal out of range for `{}`", t.name_str()),
280 fn lint_uint_literal<'a, 'tcx>(
281 cx: &LateContext<'a, 'tcx>,
282 e: &'tcx hir::Expr<'tcx>,
286 let uint_type = t.normalize(cx.sess().target.ptr_width);
287 let (min, max) = uint_ty_range(uint_type);
288 let lit_val: u128 = match lit.node {
289 // _v is u8, within range by definition
290 ast::LitKind::Byte(_v) => return,
291 ast::LitKind::Int(v, _) => v,
294 if lit_val < min || lit_val > max {
295 let parent_id = cx.tcx.hir().get_parent_node(e.hir_id);
296 if let Node::Expr(par_e) = cx.tcx.hir().get(parent_id) {
298 hir::ExprKind::Cast(..) => {
299 if let ty::Char = cx.tables.expr_ty(par_e).kind {
300 let mut err = cx.struct_span_lint(
301 OVERFLOWING_LITERALS,
303 "only `u8` can be cast into `char`",
307 &"use a `char` literal instead",
308 format!("'\\u{{{:X}}}'", lit_val),
309 Applicability::MachineApplicable,
315 hir::ExprKind::Struct(..) if is_range_literal(cx.sess().source_map(), par_e) => {
316 let t = t.name_str();
317 if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, par_e, t) {
318 // The overflowing literal lint was overridden.
325 if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
326 report_bin_hex_error(cx, e, attr::IntType::UnsignedInt(t), repr_str, lit_val, false);
330 OVERFLOWING_LITERALS,
332 &format!("literal out of range for `{}`", t.name_str()),
337 fn lint_literal<'a, 'tcx>(
338 cx: &LateContext<'a, 'tcx>,
339 type_limits: &TypeLimits,
340 e: &'tcx hir::Expr<'tcx>,
343 match cx.tables.node_type(e.hir_id).kind {
346 ast::LitKind::Int(v, ast::LitIntType::Signed(_))
347 | ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => {
348 lint_int_literal(cx, type_limits, e, lit, t, v)
353 ty::Uint(t) => lint_uint_literal(cx, e, lit, t),
355 let is_infinite = match lit.node {
356 ast::LitKind::Float(v, _) => match t {
357 ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite),
358 ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite),
362 if is_infinite == Ok(true) {
364 OVERFLOWING_LITERALS,
366 &format!("literal out of range for `{}`", t.name_str()),
374 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
375 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx hir::Expr<'tcx>) {
377 hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => {
378 // propagate negation, if the negation itself isn't negated
379 if self.negated_expr_id != e.hir_id {
380 self.negated_expr_id = expr.hir_id;
383 hir::ExprKind::Binary(binop, ref l, ref r) => {
384 if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
388 "comparison is useless due to type limits",
392 hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit),
396 fn is_valid<T: cmp::PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool {
398 hir::BinOpKind::Lt => v > min && v <= max,
399 hir::BinOpKind::Le => v >= min && v < max,
400 hir::BinOpKind::Gt => v >= min && v < max,
401 hir::BinOpKind::Ge => v > min && v <= max,
402 hir::BinOpKind::Eq | hir::BinOpKind::Ne => v >= min && v <= max,
407 fn rev_binop(binop: hir::BinOp) -> hir::BinOp {
411 hir::BinOpKind::Lt => hir::BinOpKind::Gt,
412 hir::BinOpKind::Le => hir::BinOpKind::Ge,
413 hir::BinOpKind::Gt => hir::BinOpKind::Lt,
414 hir::BinOpKind::Ge => hir::BinOpKind::Le,
421 cx: &LateContext<'_, '_>,
426 let (lit, expr, swap) = match (&l.kind, &r.kind) {
427 (&hir::ExprKind::Lit(_), _) => (l, r, true),
428 (_, &hir::ExprKind::Lit(_)) => (r, l, false),
431 // Normalize the binop so that the literal is always on the RHS in
433 let norm_binop = if swap { rev_binop(binop) } else { binop };
434 match cx.tables.node_type(expr.hir_id).kind {
436 let (min, max) = int_ty_range(int_ty);
437 let lit_val: i128 = match lit.kind {
438 hir::ExprKind::Lit(ref li) => match li.node {
439 ast::LitKind::Int(v, ast::LitIntType::Signed(_))
440 | ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => v as i128,
445 is_valid(norm_binop, lit_val, min, max)
447 ty::Uint(uint_ty) => {
448 let (min, max): (u128, u128) = uint_ty_range(uint_ty);
449 let lit_val: u128 = match lit.kind {
450 hir::ExprKind::Lit(ref li) => match li.node {
451 ast::LitKind::Int(v, _) => v,
456 is_valid(norm_binop, lit_val, min, max)
462 fn is_comparison(binop: hir::BinOp) -> bool {
469 | hir::BinOpKind::Gt => true,
479 "proper use of libc types in foreign modules"
482 declare_lint_pass!(ImproperCTypes => [IMPROPER_CTYPES]);
484 struct ImproperCTypesVisitor<'a, 'tcx> {
485 cx: &'a LateContext<'a, 'tcx>,
488 enum FfiResult<'tcx> {
490 FfiPhantom(Ty<'tcx>),
491 FfiUnsafe { ty: Ty<'tcx>, reason: &'static str, help: Option<&'static str> },
494 fn is_zst<'tcx>(tcx: TyCtxt<'tcx>, did: DefId, ty: Ty<'tcx>) -> bool {
495 tcx.layout_of(tcx.param_env(did).and(ty)).map(|layout| layout.is_zst()).unwrap_or(false)
498 fn ty_is_known_nonnull<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
500 ty::FnPtr(_) => true,
502 ty::Adt(field_def, substs) if field_def.repr.transparent() && !field_def.is_union() => {
503 for field in field_def.all_fields() {
505 tcx.normalize_erasing_regions(ParamEnv::reveal_all(), field.ty(tcx, substs));
506 if is_zst(tcx, field.did, field_ty) {
510 let attrs = tcx.get_attrs(field_def.did);
511 if attrs.iter().any(|a| a.check_name(sym::rustc_nonnull_optimization_guaranteed))
512 || ty_is_known_nonnull(tcx, field_ty)
524 /// Check if this enum can be safely exported based on the
525 /// "nullable pointer optimization". Currently restricted
526 /// to function pointers, references, core::num::NonZero*,
527 /// core::ptr::NonNull, and #[repr(transparent)] newtypes.
528 /// FIXME: This duplicates code in codegen.
529 fn is_repr_nullable_ptr<'tcx>(
532 ty_def: &'tcx ty::AdtDef,
533 substs: SubstsRef<'tcx>,
535 if ty_def.variants.len() != 2 {
539 let get_variant_fields = |index| &ty_def.variants[VariantIdx::new(index)].fields;
540 let variant_fields = [get_variant_fields(0), get_variant_fields(1)];
541 let fields = if variant_fields[0].is_empty() {
543 } else if variant_fields[1].is_empty() {
549 if fields.len() != 1 {
553 let field_ty = fields[0].ty(tcx, substs);
554 if !ty_is_known_nonnull(tcx, field_ty) {
558 // At this point, the field's type is known to be nonnull and the parent enum is Option-like.
559 // If the computed size for the field and the enum are different, the nonnull optimization isn't
560 // being applied (and we've got a problem somewhere).
561 let compute_size_skeleton = |t| SizeSkeleton::compute(t, tcx, ParamEnv::reveal_all()).unwrap();
562 if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) {
563 bug!("improper_ctypes: Option nonnull optimization not applied?");
569 impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
570 /// Check if the type is array and emit an unsafe type lint.
571 fn check_for_array_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
572 if let ty::Array(..) = ty.kind {
573 self.emit_ffi_unsafe_type_lint(
576 "passing raw arrays by value is not FFI-safe",
577 Some("consider passing a pointer to the array"),
585 /// Checks if the given type is "ffi-safe" (has a stable, well-defined
586 /// representation which can be exported to C code).
587 fn check_type_for_ffi(&self, cache: &mut FxHashSet<Ty<'tcx>>, ty: Ty<'tcx>) -> FfiResult<'tcx> {
590 let cx = self.cx.tcx;
592 // Protect against infinite recursion, for example
593 // `struct S(*mut S);`.
594 // FIXME: A recursion limit is necessary as well, for irregular
596 if !cache.insert(ty) {
601 ty::Adt(def, substs) => {
602 if def.is_phantom_data() {
603 return FfiPhantom(ty);
605 match def.adt_kind() {
607 if !def.repr.c() && !def.repr.transparent() {
610 reason: "this struct has unspecified layout",
612 "consider adding a `#[repr(C)]` or \
613 `#[repr(transparent)]` attribute to this struct",
618 let is_non_exhaustive =
619 def.non_enum_variant().is_field_list_non_exhaustive();
620 if is_non_exhaustive && !def.did.is_local() {
623 reason: "this struct is non-exhaustive",
628 if def.non_enum_variant().fields.is_empty() {
631 reason: "this struct has no fields",
632 help: Some("consider adding a member to this struct"),
636 // We can't completely trust repr(C) and repr(transparent) markings;
637 // make sure the fields are actually safe.
638 let mut all_phantom = true;
639 for field in &def.non_enum_variant().fields {
640 let field_ty = cx.normalize_erasing_regions(
641 ParamEnv::reveal_all(),
642 field.ty(cx, substs),
644 // repr(transparent) types are allowed to have arbitrary ZSTs, not just
645 // PhantomData -- skip checking all ZST fields
646 if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
649 let r = self.check_type_for_ffi(cache, field_ty);
655 FfiUnsafe { .. } => {
661 if all_phantom { FfiPhantom(ty) } else { FfiSafe }
664 if !def.repr.c() && !def.repr.transparent() {
667 reason: "this union has unspecified layout",
669 "consider adding a `#[repr(C)]` or \
670 `#[repr(transparent)]` attribute to this union",
675 if def.non_enum_variant().fields.is_empty() {
678 reason: "this union has no fields",
679 help: Some("consider adding a field to this union"),
683 let mut all_phantom = true;
684 for field in &def.non_enum_variant().fields {
685 let field_ty = cx.normalize_erasing_regions(
686 ParamEnv::reveal_all(),
687 field.ty(cx, substs),
689 // repr(transparent) types are allowed to have arbitrary ZSTs, not just
690 // PhantomData -- skip checking all ZST fields.
691 if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
694 let r = self.check_type_for_ffi(cache, field_ty);
700 FfiUnsafe { .. } => {
706 if all_phantom { FfiPhantom(ty) } else { FfiSafe }
709 if def.variants.is_empty() {
710 // Empty enums are okay... although sort of useless.
714 // Check for a repr() attribute to specify the size of the
716 if !def.repr.c() && !def.repr.transparent() && def.repr.int.is_none() {
717 // Special-case types like `Option<extern fn()>`.
718 if !is_repr_nullable_ptr(cx, ty, def, substs) {
721 reason: "enum has no representation hint",
723 "consider adding a `#[repr(C)]`, \
724 `#[repr(transparent)]`, or integer `#[repr(...)]` \
725 attribute to this enum",
731 if def.is_variant_list_non_exhaustive() && !def.did.is_local() {
734 reason: "this enum is non-exhaustive",
739 // Check the contained variants.
740 for variant in &def.variants {
741 let is_non_exhaustive = variant.is_field_list_non_exhaustive();
742 if is_non_exhaustive && !variant.def_id.is_local() {
745 reason: "this enum has non-exhaustive variants",
750 for field in &variant.fields {
751 let field_ty = cx.normalize_erasing_regions(
752 ParamEnv::reveal_all(),
753 field.ty(cx, substs),
755 // repr(transparent) types are allowed to have arbitrary ZSTs, not
756 // just PhantomData -- skip checking all ZST fields.
757 if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
760 let r = self.check_type_for_ffi(cache, field_ty);
763 FfiUnsafe { .. } => {
769 reason: "this enum contains a PhantomData field",
781 ty::Char => FfiUnsafe {
783 reason: "the `char` type has no C equivalent",
784 help: Some("consider using `u32` or `libc::wchar_t` instead"),
787 ty::Int(ast::IntTy::I128) | ty::Uint(ast::UintTy::U128) => FfiUnsafe {
789 reason: "128-bit integers don't currently have a known stable ABI",
793 // Primitive types with a stable representation.
794 ty::Bool | ty::Int(..) | ty::Uint(..) | ty::Float(..) | ty::Never => FfiSafe,
796 ty::Slice(_) => FfiUnsafe {
798 reason: "slices have no C equivalent",
799 help: Some("consider using a raw pointer instead"),
803 FfiUnsafe { ty, reason: "trait objects have no C equivalent", help: None }
806 ty::Str => FfiUnsafe {
808 reason: "string slices have no C equivalent",
809 help: Some("consider using `*const u8` and a length instead"),
812 ty::Tuple(..) => FfiUnsafe {
814 reason: "tuples have unspecified layout",
815 help: Some("consider using a struct instead"),
818 ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) => {
819 self.check_type_for_ffi(cache, ty)
822 ty::Array(inner_ty, _) => self.check_type_for_ffi(cache, inner_ty),
826 Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic | Abi::RustCall => {
829 reason: "this function pointer has Rust-specific calling convention",
831 "consider using an `extern fn(...) -> ...` \
832 function pointer instead",
839 let sig = cx.erase_late_bound_regions(&sig);
840 if !sig.output().is_unit() {
841 let r = self.check_type_for_ffi(cache, sig.output());
849 for arg in sig.inputs() {
850 let r = self.check_type_for_ffi(cache, arg);
861 ty::Foreign(..) => FfiSafe,
869 | ty::GeneratorWitness(..)
870 | ty::Placeholder(..)
871 | ty::UnnormalizedProjection(..)
874 | ty::FnDef(..) => bug!("unexpected type in foreign function: {:?}", ty),
878 fn emit_ffi_unsafe_type_lint(
885 let mut diag = self.cx.struct_span_lint(
888 &format!("`extern` block uses type `{}`, which is not FFI-safe", ty),
890 diag.span_label(sp, "not FFI-safe");
891 if let Some(help) = help {
895 if let ty::Adt(def, _) = ty.kind {
896 if let Some(sp) = self.cx.tcx.hir().span_if_local(def.did) {
897 diag.span_note(sp, "type defined here");
903 fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
904 use crate::rustc::ty::TypeFoldable;
906 struct ProhibitOpaqueTypes<'tcx> {
907 ty: Option<Ty<'tcx>>,
910 impl<'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueTypes<'tcx> {
911 fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
912 if let ty::Opaque(..) = ty.kind {
916 ty.super_visit_with(self)
921 let mut visitor = ProhibitOpaqueTypes { ty: None };
922 ty.visit_with(&mut visitor);
923 if let Some(ty) = visitor.ty {
924 self.emit_ffi_unsafe_type_lint(ty, sp, "opaque types have no C equivalent", None);
931 fn check_type_for_ffi_and_report_errors(&mut self, sp: Span, ty: Ty<'tcx>, is_static: bool) {
932 // We have to check for opaque types before `normalize_erasing_regions`,
933 // which will replace opaque types with their underlying concrete type.
934 if self.check_for_opaque_ty(sp, ty) {
935 // We've already emitted an error due to an opaque type.
939 // it is only OK to use this function because extern fns cannot have
940 // any generic types right now:
941 let ty = self.cx.tcx.normalize_erasing_regions(ParamEnv::reveal_all(), ty);
942 // C doesn't really support passing arrays by value.
943 // The only way to pass an array by value is through a struct.
944 // So we first test that the top level isn't an array,
945 // and then recursively check the types inside.
946 if !is_static && self.check_for_array_ty(sp, ty) {
950 match self.check_type_for_ffi(&mut FxHashSet::default(), ty) {
951 FfiResult::FfiSafe => {}
952 FfiResult::FfiPhantom(ty) => {
953 self.emit_ffi_unsafe_type_lint(ty, sp, "composed only of `PhantomData`", None);
955 FfiResult::FfiUnsafe { ty, reason, help } => {
956 self.emit_ffi_unsafe_type_lint(ty, sp, reason, help);
961 fn check_foreign_fn(&mut self, id: hir::HirId, decl: &hir::FnDecl<'_>) {
962 let def_id = self.cx.tcx.hir().local_def_id(id);
963 let sig = self.cx.tcx.fn_sig(def_id);
964 let sig = self.cx.tcx.erase_late_bound_regions(&sig);
966 for (input_ty, input_hir) in sig.inputs().iter().zip(decl.inputs) {
967 self.check_type_for_ffi_and_report_errors(input_hir.span, input_ty, false);
970 if let hir::FunctionRetTy::Return(ref ret_hir) = decl.output {
971 let ret_ty = sig.output();
972 if !ret_ty.is_unit() {
973 self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty, false);
978 fn check_foreign_static(&mut self, id: hir::HirId, span: Span) {
979 let def_id = self.cx.tcx.hir().local_def_id(id);
980 let ty = self.cx.tcx.type_of(def_id);
981 self.check_type_for_ffi_and_report_errors(span, ty, true);
985 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImproperCTypes {
986 fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::ForeignItem<'_>) {
987 let mut vis = ImproperCTypesVisitor { cx };
988 let abi = cx.tcx.hir().get_foreign_abi(it.hir_id);
989 if let Abi::Rust | Abi::RustCall | Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
990 // Don't worry about types in internal ABIs.
993 hir::ForeignItemKind::Fn(ref decl, _, _) => {
994 vis.check_foreign_fn(it.hir_id, decl);
996 hir::ForeignItemKind::Static(ref ty, _) => {
997 vis.check_foreign_static(it.hir_id, ty.span);
999 hir::ForeignItemKind::Type => (),
1005 declare_lint_pass!(VariantSizeDifferences => [VARIANT_SIZE_DIFFERENCES]);
1007 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VariantSizeDifferences {
1008 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item<'_>) {
1009 if let hir::ItemKind::Enum(ref enum_definition, _) = it.kind {
1010 let item_def_id = cx.tcx.hir().local_def_id(it.hir_id);
1011 let t = cx.tcx.type_of(item_def_id);
1012 let ty = cx.tcx.erase_regions(&t);
1013 let layout = match cx.layout_of(ty) {
1014 Ok(layout) => layout,
1015 Err(ty::layout::LayoutError::Unknown(_)) => return,
1016 Err(err @ ty::layout::LayoutError::SizeOverflow(_)) => {
1017 bug!("failed to get layout for `{}`: {}", t, err);
1020 let (variants, tag) = match layout.variants {
1021 layout::Variants::Multiple {
1022 discr_kind: layout::DiscriminantKind::Tag,
1026 } => (variants, discr),
1030 let discr_size = tag.value.size(&cx.tcx).bytes();
1033 "enum `{}` is {} bytes large with layout:\n{:#?}",
1035 layout.size.bytes(),
1039 let (largest, slargest, largest_index) = enum_definition
1043 .map(|(variant, variant_layout)| {
1044 // Subtract the size of the enum discriminant.
1045 let bytes = variant_layout.size.bytes().saturating_sub(discr_size);
1047 debug!("- variant `{}` is {} bytes large", variant.ident, bytes);
1051 .fold((0, 0, 0), |(l, s, li), (idx, size)| {
1054 } else if size > s {
1061 // We only warn if the largest variant is at least thrice as large as
1062 // the second-largest.
1063 if largest > slargest * 3 && slargest > 0 {
1065 VARIANT_SIZE_DIFFERENCES,
1066 enum_definition.variants[largest_index].span,
1068 "enum variant is more than three times \
1069 larger ({} bytes) than the next largest",