1 #![allow(non_snake_case)]
3 use rustc::hir::{ExprKind, Node};
4 use crate::hir::def_id::DefId;
5 use rustc::hir::lowering::is_range_literal;
6 use rustc::ty::subst::SubstsRef;
7 use rustc::ty::{self, AdtKind, ParamEnv, Ty, TyCtxt};
8 use rustc::ty::layout::{self, IntegerExt, LayoutOf, VariantIdx, SizeSkeleton};
9 use rustc::{lint, util};
10 use rustc_index::vec::Idx;
11 use util::nodemap::FxHashSet;
12 use lint::{LateContext, LintContext, LintArray};
13 use lint::{LintPass, LateLintPass};
16 use std::{i8, i16, i32, i64, u8, u16, u32, u64, f32, f64};
18 use syntax::{ast, attr, source_map};
19 use syntax::errors::Applicability;
20 use syntax::symbol::sym;
21 use rustc_target::spec::abi::Abi;
26 use rustc::mir::interpret::{sign_extend, truncate};
33 "comparisons made useless by limits of the types involved"
39 "literal out of range for its type"
43 VARIANT_SIZE_DIFFERENCES,
45 "detects enums with widely varying variant sizes"
48 #[derive(Copy, Clone)]
49 pub struct TypeLimits {
50 /// Id of the last visited negated expression
51 negated_expr_id: hir::HirId,
54 impl_lint_pass!(TypeLimits => [UNUSED_COMPARISONS, OVERFLOWING_LITERALS]);
57 pub fn new() -> TypeLimits {
58 TypeLimits { negated_expr_id: hir::DUMMY_HIR_ID }
62 /// Attempts to special-case the overflowing literal lint when it occurs as a range endpoint.
63 /// Returns `true` iff the lint was overridden.
64 fn lint_overflowing_range_endpoint<'a, 'tcx>(
65 cx: &LateContext<'a, 'tcx>,
69 expr: &'tcx hir::Expr,
70 parent_expr: &'tcx hir::Expr,
71 ty: impl std::fmt::Debug,
73 // We only want to handle exclusive (`..`) ranges,
74 // which are represented as `ExprKind::Struct`.
75 if let ExprKind::Struct(_, eps, _) = &parent_expr.kind {
79 // We can suggest using an inclusive range
80 // (`..=`) instead only if it is the `end` that is
81 // overflowing and only by 1.
82 if eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max {
83 let mut err = cx.struct_span_lint(
86 &format!("range endpoint is out of range for `{:?}`", ty),
88 if let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) {
89 use ast::{LitKind, LitIntType};
90 // We need to preserve the literal's suffix,
91 // as it may determine typing information.
92 let suffix = match lit.node {
93 LitKind::Int(_, LitIntType::Signed(s)) => format!("{}", s),
94 LitKind::Int(_, LitIntType::Unsigned(s)) => format!("{}", s),
95 LitKind::Int(_, LitIntType::Unsuffixed) => "".to_owned(),
98 let suggestion = format!("{}..={}{}", start, lit_val - 1, suffix);
101 &"use an inclusive range instead",
103 Applicability::MachineApplicable,
114 // For `isize` & `usize`, be conservative with the warnings, so that the
115 // warnings are consistent between 32- and 64-bit platforms.
116 fn int_ty_range(int_ty: ast::IntTy) -> (i128, i128) {
118 ast::IntTy::Isize => (i64::min_value() as i128, i64::max_value() as i128),
119 ast::IntTy::I8 => (i8::min_value() as i64 as i128, i8::max_value() as i128),
120 ast::IntTy::I16 => (i16::min_value() as i64 as i128, i16::max_value() as i128),
121 ast::IntTy::I32 => (i32::min_value() as i64 as i128, i32::max_value() as i128),
122 ast::IntTy::I64 => (i64::min_value() as i128, i64::max_value() as i128),
123 ast::IntTy::I128 =>(i128::min_value() as i128, i128::max_value()),
127 fn uint_ty_range(uint_ty: ast::UintTy) -> (u128, u128) {
129 ast::UintTy::Usize => (u64::min_value() as u128, u64::max_value() as u128),
130 ast::UintTy::U8 => (u8::min_value() as u128, u8::max_value() as u128),
131 ast::UintTy::U16 => (u16::min_value() as u128, u16::max_value() as u128),
132 ast::UintTy::U32 => (u32::min_value() as u128, u32::max_value() as u128),
133 ast::UintTy::U64 => (u64::min_value() as u128, u64::max_value() as u128),
134 ast::UintTy::U128 => (u128::min_value(), u128::max_value()),
138 fn get_bin_hex_repr(cx: &LateContext<'_, '_>, lit: &hir::Lit) -> Option<String> {
139 let src = cx.sess().source_map().span_to_snippet(lit.span).ok()?;
140 let firstch = src.chars().next()?;
143 match src.chars().nth(1) {
144 Some('x') | Some('b') => return Some(src),
152 fn report_bin_hex_error(
153 cx: &LateContext<'_, '_>,
160 let size = layout::Integer::from_attr(&cx.tcx, ty).size();
161 let (t, actually) = match ty {
162 attr::IntType::SignedInt(t) => {
163 let actually = sign_extend(val, size) as i128;
164 (format!("{:?}", t), actually.to_string())
166 attr::IntType::UnsignedInt(t) => {
167 let actually = truncate(val, size);
168 (format!("{:?}", t), actually.to_string())
171 let mut err = cx.struct_span_lint(
172 OVERFLOWING_LITERALS,
174 &format!("literal out of range for {}", t),
177 "the literal `{}` (decimal `{}`) does not fit into \
178 an `{}` and will become `{}{}`",
179 repr_str, val, t, actually, t
181 if let Some(sugg_ty) =
182 get_type_suggestion(&cx.tables.node_type(expr.hir_id), val, negative)
184 if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') {
185 let (sans_suffix, _) = repr_str.split_at(pos);
188 &format!("consider using `{}` instead", sugg_ty),
189 format!("{}{}", sans_suffix, sugg_ty),
190 Applicability::MachineApplicable
193 err.help(&format!("consider using `{}` instead", sugg_ty));
200 // This function finds the next fitting type and generates a suggestion string.
201 // It searches for fitting types in the following way (`X < Y`):
202 // - `iX`: if literal fits in `uX` => `uX`, else => `iY`
206 // No suggestion for: `isize`, `usize`.
207 fn get_type_suggestion(t: Ty<'_>, val: u128, negative: bool) -> Option<String> {
208 use syntax::ast::IntTy::*;
209 use syntax::ast::UintTy::*;
210 macro_rules! find_fit {
211 ($ty:expr, $val:expr, $negative:expr,
212 $($type:ident => [$($utypes:expr),*] => [$($itypes:expr),*]),+) => {
214 let _neg = if negative { 1 } else { 0 };
217 $(if !negative && val <= uint_ty_range($utypes).1 {
218 return Some(format!("{:?}", $utypes))
220 $(if val <= int_ty_range($itypes).1 as u128 + _neg {
221 return Some(format!("{:?}", $itypes))
231 ty::Int(i) => find_fit!(i, val, negative,
232 I8 => [U8] => [I16, I32, I64, I128],
233 I16 => [U16] => [I32, I64, I128],
234 I32 => [U32] => [I64, I128],
235 I64 => [U64] => [I128],
236 I128 => [U128] => []),
237 ty::Uint(u) => find_fit!(u, val, negative,
238 U8 => [U8, U16, U32, U64, U128] => [],
239 U16 => [U16, U32, U64, U128] => [],
240 U32 => [U32, U64, U128] => [],
241 U64 => [U64, U128] => [],
242 U128 => [U128] => []),
247 fn lint_int_literal<'a, 'tcx>(
248 cx: &LateContext<'a, 'tcx>,
249 type_limits: &TypeLimits,
255 let int_type = if let ast::IntTy::Isize = t {
256 cx.sess().target.isize_ty
261 let (_, max) = int_ty_range(int_type);
262 let max = max as u128;
263 let negative = type_limits.negated_expr_id == e.hir_id;
265 // Detect literal value out of range [min, max] inclusive
266 // avoiding use of -min to prevent overflow/panic
267 if (negative && v > max + 1) || (!negative && v > max) {
268 if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
269 report_bin_hex_error(
272 attr::IntType::SignedInt(t),
280 let par_id = cx.tcx.hir().get_parent_node(e.hir_id);
281 if let Node::Expr(par_e) = cx.tcx.hir().get(par_id) {
282 if let hir::ExprKind::Struct(..) = par_e.kind {
283 if is_range_literal(cx.sess(), par_e)
284 && lint_overflowing_range_endpoint(cx, lit, v, max, e, par_e, t)
286 // The overflowing literal lint was overridden.
293 OVERFLOWING_LITERALS,
295 &format!("literal out of range for `{:?}`", t),
300 fn lint_uint_literal<'a, 'tcx>(
301 cx: &LateContext<'a, 'tcx>,
306 let uint_type = if let ast::UintTy::Usize = t {
307 cx.sess().target.usize_ty
311 let (min, max) = uint_ty_range(uint_type);
312 let lit_val: u128 = match lit.node {
313 // _v is u8, within range by definition
314 ast::LitKind::Byte(_v) => return,
315 ast::LitKind::Int(v, _) => v,
318 if lit_val < min || lit_val > max {
319 let parent_id = cx.tcx.hir().get_parent_node(e.hir_id);
320 if let Node::Expr(par_e) = cx.tcx.hir().get(parent_id) {
322 hir::ExprKind::Cast(..) => {
323 if let ty::Char = cx.tables.expr_ty(par_e).kind {
324 let mut err = cx.struct_span_lint(
325 OVERFLOWING_LITERALS,
327 "only `u8` can be cast into `char`",
331 &"use a `char` literal instead",
332 format!("'\\u{{{:X}}}'", lit_val),
333 Applicability::MachineApplicable,
339 hir::ExprKind::Struct(..)
340 if is_range_literal(cx.sess(), par_e) => {
341 if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, par_e, t) {
342 // The overflowing literal lint was overridden.
349 if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
350 report_bin_hex_error(cx, e, attr::IntType::UnsignedInt(t), repr_str, lit_val, false);
354 OVERFLOWING_LITERALS,
356 &format!("literal out of range for `{:?}`", t),
361 fn lint_literal<'a, 'tcx>(
362 cx: &LateContext<'a, 'tcx>,
363 type_limits: &TypeLimits,
367 match cx.tables.node_type(e.hir_id).kind {
370 ast::LitKind::Int(v, ast::LitIntType::Signed(_)) |
371 ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => {
372 lint_int_literal(cx, type_limits, e, lit, t, v)
378 lint_uint_literal(cx, e, lit, t)
381 let is_infinite = match lit.node {
382 ast::LitKind::Float(v, _) |
383 ast::LitKind::FloatUnsuffixed(v) => {
385 ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite),
386 ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite),
391 if is_infinite == Ok(true) {
392 cx.span_lint(OVERFLOWING_LITERALS,
394 &format!("literal out of range for `{:?}`", t));
401 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
402 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx hir::Expr) {
404 hir::ExprKind::Unary(hir::UnNeg, ref expr) => {
405 // propagate negation, if the negation itself isn't negated
406 if self.negated_expr_id != e.hir_id {
407 self.negated_expr_id = expr.hir_id;
410 hir::ExprKind::Binary(binop, ref l, ref r) => {
411 if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
412 cx.span_lint(UNUSED_COMPARISONS,
414 "comparison is useless due to type limits");
417 hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit),
421 fn is_valid<T: cmp::PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool {
423 hir::BinOpKind::Lt => v > min && v <= max,
424 hir::BinOpKind::Le => v >= min && v < max,
425 hir::BinOpKind::Gt => v >= min && v < max,
426 hir::BinOpKind::Ge => v > min && v <= max,
427 hir::BinOpKind::Eq | hir::BinOpKind::Ne => v >= min && v <= max,
432 fn rev_binop(binop: hir::BinOp) -> hir::BinOp {
433 source_map::respan(binop.span,
435 hir::BinOpKind::Lt => hir::BinOpKind::Gt,
436 hir::BinOpKind::Le => hir::BinOpKind::Ge,
437 hir::BinOpKind::Gt => hir::BinOpKind::Lt,
438 hir::BinOpKind::Ge => hir::BinOpKind::Le,
443 fn check_limits(cx: &LateContext<'_, '_>,
448 let (lit, expr, swap) = match (&l.kind, &r.kind) {
449 (&hir::ExprKind::Lit(_), _) => (l, r, true),
450 (_, &hir::ExprKind::Lit(_)) => (r, l, false),
453 // Normalize the binop so that the literal is always on the RHS in
455 let norm_binop = if swap { rev_binop(binop) } else { binop };
456 match cx.tables.node_type(expr.hir_id).kind {
458 let (min, max) = int_ty_range(int_ty);
459 let lit_val: i128 = match lit.kind {
460 hir::ExprKind::Lit(ref li) => {
462 ast::LitKind::Int(v, ast::LitIntType::Signed(_)) |
463 ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => v as i128,
469 is_valid(norm_binop, lit_val, min, max)
471 ty::Uint(uint_ty) => {
472 let (min, max) :(u128, u128) = uint_ty_range(uint_ty);
473 let lit_val: u128 = match lit.kind {
474 hir::ExprKind::Lit(ref li) => {
476 ast::LitKind::Int(v, _) => v,
482 is_valid(norm_binop, lit_val, min, max)
488 fn is_comparison(binop: hir::BinOp) -> bool {
495 hir::BinOpKind::Gt => true,
505 "proper use of libc types in foreign modules"
508 declare_lint_pass!(ImproperCTypes => [IMPROPER_CTYPES]);
510 struct ImproperCTypesVisitor<'a, 'tcx> {
511 cx: &'a LateContext<'a, 'tcx>,
514 enum FfiResult<'tcx> {
516 FfiPhantom(Ty<'tcx>),
519 reason: &'static str,
520 help: Option<&'static str>,
524 fn is_zst<'tcx>(tcx: TyCtxt<'tcx>, did: DefId, ty: Ty<'tcx>) -> bool {
525 tcx.layout_of(tcx.param_env(did).and(ty)).map(|layout| layout.is_zst()).unwrap_or(false)
528 fn ty_is_known_nonnull<'tcx>(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> bool {
530 ty::FnPtr(_) => true,
532 ty::Adt(field_def, substs) if field_def.repr.transparent() && !field_def.is_union() => {
533 for field in field_def.all_fields() {
534 let field_ty = tcx.normalize_erasing_regions(
535 ParamEnv::reveal_all(),
536 field.ty(tcx, substs),
538 if is_zst(tcx, field.did, field_ty) {
542 let attrs = tcx.get_attrs(field_def.did);
543 if attrs.iter().any(|a| a.check_name(sym::rustc_nonnull_optimization_guaranteed)) ||
544 ty_is_known_nonnull(tcx, field_ty) {
555 /// Check if this enum can be safely exported based on the
556 /// "nullable pointer optimization". Currently restricted
557 /// to function pointers, references, core::num::NonZero*,
558 /// core::ptr::NonNull, and #[repr(transparent)] newtypes.
559 /// FIXME: This duplicates code in codegen.
560 fn is_repr_nullable_ptr<'tcx>(
563 ty_def: &'tcx ty::AdtDef,
564 substs: SubstsRef<'tcx>,
566 if ty_def.variants.len() != 2 {
570 let get_variant_fields = |index| &ty_def.variants[VariantIdx::new(index)].fields;
571 let variant_fields = [get_variant_fields(0), get_variant_fields(1)];
572 let fields = if variant_fields[0].is_empty() {
574 } else if variant_fields[1].is_empty() {
580 if fields.len() != 1 {
584 let field_ty = fields[0].ty(tcx, substs);
585 if !ty_is_known_nonnull(tcx, field_ty) {
589 // At this point, the field's type is known to be nonnull and the parent enum is Option-like.
590 // If the computed size for the field and the enum are different, the nonnull optimization isn't
591 // being applied (and we've got a problem somewhere).
592 let compute_size_skeleton = |t| SizeSkeleton::compute(t, tcx, ParamEnv::reveal_all()).unwrap();
593 if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) {
594 bug!("improper_ctypes: Option nonnull optimization not applied?");
600 impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
601 /// Checks if the given type is "ffi-safe" (has a stable, well-defined
602 /// representation which can be exported to C code).
603 fn check_type_for_ffi(&self,
604 cache: &mut FxHashSet<Ty<'tcx>>,
605 ty: Ty<'tcx>) -> FfiResult<'tcx> {
608 let cx = self.cx.tcx;
610 // Protect against infinite recursion, for example
611 // `struct S(*mut S);`.
612 // FIXME: A recursion limit is necessary as well, for irregular
614 if !cache.insert(ty) {
619 ty::Adt(def, substs) => {
620 if def.is_phantom_data() {
621 return FfiPhantom(ty);
623 match def.adt_kind() {
625 if !def.repr.c() && !def.repr.transparent() {
628 reason: "this struct has unspecified layout",
629 help: Some("consider adding a `#[repr(C)]` or \
630 `#[repr(transparent)]` attribute to this struct"),
634 let is_non_exhaustive =
635 def.non_enum_variant().is_field_list_non_exhaustive();
636 if is_non_exhaustive && !def.did.is_local() {
639 reason: "this struct is non-exhaustive",
644 if def.non_enum_variant().fields.is_empty() {
647 reason: "this struct has no fields",
648 help: Some("consider adding a member to this struct"),
652 // We can't completely trust repr(C) and repr(transparent) markings;
653 // make sure the fields are actually safe.
654 let mut all_phantom = true;
655 for field in &def.non_enum_variant().fields {
656 let field_ty = cx.normalize_erasing_regions(
657 ParamEnv::reveal_all(),
658 field.ty(cx, substs),
660 // repr(transparent) types are allowed to have arbitrary ZSTs, not just
661 // PhantomData -- skip checking all ZST fields
662 if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
665 let r = self.check_type_for_ffi(cache, field_ty);
671 FfiUnsafe { .. } => {
677 if all_phantom { FfiPhantom(ty) } else { FfiSafe }
680 if !def.repr.c() && !def.repr.transparent() {
683 reason: "this union has unspecified layout",
684 help: Some("consider adding a `#[repr(C)]` or \
685 `#[repr(transparent)]` attribute to this union"),
689 if def.non_enum_variant().fields.is_empty() {
692 reason: "this union has no fields",
693 help: Some("consider adding a field to this union"),
697 let mut all_phantom = true;
698 for field in &def.non_enum_variant().fields {
699 let field_ty = cx.normalize_erasing_regions(
700 ParamEnv::reveal_all(),
701 field.ty(cx, substs),
703 // repr(transparent) types are allowed to have arbitrary ZSTs, not just
704 // PhantomData -- skip checking all ZST fields.
705 if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
708 let r = self.check_type_for_ffi(cache, field_ty);
714 FfiUnsafe { .. } => {
720 if all_phantom { FfiPhantom(ty) } else { FfiSafe }
723 if def.variants.is_empty() {
724 // Empty enums are okay... although sort of useless.
728 // Check for a repr() attribute to specify the size of the
730 if !def.repr.c() && !def.repr.transparent() && def.repr.int.is_none() {
731 // Special-case types like `Option<extern fn()>`.
732 if !is_repr_nullable_ptr(cx, ty, def, substs) {
735 reason: "enum has no representation hint",
736 help: Some("consider adding a `#[repr(C)]`, \
737 `#[repr(transparent)]`, or integer `#[repr(...)]` \
738 attribute to this enum"),
743 if def.is_variant_list_non_exhaustive() && !def.did.is_local() {
746 reason: "this enum is non-exhaustive",
751 // Check the contained variants.
752 for variant in &def.variants {
753 let is_non_exhaustive = variant.is_field_list_non_exhaustive();
754 if is_non_exhaustive && !variant.def_id.is_local() {
757 reason: "this enum has non-exhaustive variants",
762 for field in &variant.fields {
763 let field_ty = cx.normalize_erasing_regions(
764 ParamEnv::reveal_all(),
765 field.ty(cx, substs),
767 // repr(transparent) types are allowed to have arbitrary ZSTs, not
768 // just PhantomData -- skip checking all ZST fields.
769 if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
772 let r = self.check_type_for_ffi(cache, field_ty);
775 FfiUnsafe { .. } => {
781 reason: "this enum contains a PhantomData field",
793 ty::Char => FfiUnsafe {
795 reason: "the `char` type has no C equivalent",
796 help: Some("consider using `u32` or `libc::wchar_t` instead"),
799 ty::Int(ast::IntTy::I128) | ty::Uint(ast::UintTy::U128) => FfiUnsafe {
801 reason: "128-bit integers don't currently have a known stable ABI",
805 // Primitive types with a stable representation.
806 ty::Bool | ty::Int(..) | ty::Uint(..) | ty::Float(..) | ty::Never => FfiSafe,
808 ty::Slice(_) => FfiUnsafe {
810 reason: "slices have no C equivalent",
811 help: Some("consider using a raw pointer instead"),
814 ty::Dynamic(..) => FfiUnsafe {
816 reason: "trait objects have no C equivalent",
820 ty::Str => FfiUnsafe {
822 reason: "string slices have no C equivalent",
823 help: Some("consider using `*const u8` and a length instead"),
826 ty::Tuple(..) => FfiUnsafe {
828 reason: "tuples have unspecified layout",
829 help: Some("consider using a struct instead"),
832 ty::RawPtr(ty::TypeAndMut { ty, .. }) |
833 ty::Ref(_, ty, _) => self.check_type_for_ffi(cache, ty),
835 ty::Array(ty, _) => self.check_type_for_ffi(cache, ty),
839 Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic | Abi::RustCall => {
842 reason: "this function pointer has Rust-specific calling convention",
843 help: Some("consider using an `extern fn(...) -> ...` \
844 function pointer instead"),
850 let sig = cx.erase_late_bound_regions(&sig);
851 if !sig.output().is_unit() {
852 let r = self.check_type_for_ffi(cache, sig.output());
860 for arg in sig.inputs() {
861 let r = self.check_type_for_ffi(cache, arg);
872 ty::Foreign(..) => FfiSafe,
880 ty::GeneratorWitness(..) |
881 ty::Placeholder(..) |
882 ty::UnnormalizedProjection(..) |
885 ty::FnDef(..) => bug!("unexpected type in foreign function: {:?}", ty),
889 fn emit_ffi_unsafe_type_lint(
896 let mut diag = self.cx.struct_span_lint(
899 &format!("`extern` block uses type `{}`, which is not FFI-safe", ty),
901 diag.span_label(sp, "not FFI-safe");
902 if let Some(help) = help {
906 if let ty::Adt(def, _) = ty.kind {
907 if let Some(sp) = self.cx.tcx.hir().span_if_local(def.did) {
908 diag.span_note(sp, "type defined here");
914 fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
915 use crate::rustc::ty::TypeFoldable;
917 struct ProhibitOpaqueTypes<'tcx> {
918 ty: Option<Ty<'tcx>>,
921 impl<'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueTypes<'tcx> {
922 fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
923 if let ty::Opaque(..) = ty.kind {
927 ty.super_visit_with(self)
932 let mut visitor = ProhibitOpaqueTypes { ty: None };
933 ty.visit_with(&mut visitor);
934 if let Some(ty) = visitor.ty {
935 self.emit_ffi_unsafe_type_lint(
938 "opaque types have no C equivalent",
947 fn check_type_for_ffi_and_report_errors(&mut self, sp: Span, ty: Ty<'tcx>) {
948 // We have to check for opaque types before `normalize_erasing_regions`,
949 // which will replace opaque types with their underlying concrete type.
950 if self.check_for_opaque_ty(sp, ty) {
951 // We've already emitted an error due to an opaque type.
955 // it is only OK to use this function because extern fns cannot have
956 // any generic types right now:
957 let ty = self.cx.tcx.normalize_erasing_regions(ParamEnv::reveal_all(), ty);
959 match self.check_type_for_ffi(&mut FxHashSet::default(), ty) {
960 FfiResult::FfiSafe => {}
961 FfiResult::FfiPhantom(ty) => {
962 self.emit_ffi_unsafe_type_lint(ty, sp, "composed only of `PhantomData`", None);
964 FfiResult::FfiUnsafe { ty, reason, help } => {
965 self.emit_ffi_unsafe_type_lint(ty, sp, reason, help);
970 fn check_foreign_fn(&mut self, id: hir::HirId, decl: &hir::FnDecl) {
971 let def_id = self.cx.tcx.hir().local_def_id(id);
972 let sig = self.cx.tcx.fn_sig(def_id);
973 let sig = self.cx.tcx.erase_late_bound_regions(&sig);
975 for (input_ty, input_hir) in sig.inputs().iter().zip(&decl.inputs) {
976 self.check_type_for_ffi_and_report_errors(input_hir.span, input_ty);
979 if let hir::Return(ref ret_hir) = decl.output {
980 let ret_ty = sig.output();
981 if !ret_ty.is_unit() {
982 self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty);
987 fn check_foreign_static(&mut self, id: hir::HirId, span: Span) {
988 let def_id = self.cx.tcx.hir().local_def_id(id);
989 let ty = self.cx.tcx.type_of(def_id);
990 self.check_type_for_ffi_and_report_errors(span, ty);
994 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImproperCTypes {
995 fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::ForeignItem) {
996 let mut vis = ImproperCTypesVisitor { cx };
997 let abi = cx.tcx.hir().get_foreign_abi(it.hir_id);
998 if let Abi::Rust | Abi::RustCall | Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
999 // Don't worry about types in internal ABIs.
1002 hir::ForeignItemKind::Fn(ref decl, _, _) => {
1003 vis.check_foreign_fn(it.hir_id, decl);
1005 hir::ForeignItemKind::Static(ref ty, _) => {
1006 vis.check_foreign_static(it.hir_id, ty.span);
1008 hir::ForeignItemKind::Type => ()
1014 declare_lint_pass!(VariantSizeDifferences => [VARIANT_SIZE_DIFFERENCES]);
1016 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VariantSizeDifferences {
1017 fn check_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::Item) {
1018 if let hir::ItemKind::Enum(ref enum_definition, _) = it.kind {
1019 let item_def_id = cx.tcx.hir().local_def_id(it.hir_id);
1020 let t = cx.tcx.type_of(item_def_id);
1021 let ty = cx.tcx.erase_regions(&t);
1022 let layout = match cx.layout_of(ty) {
1023 Ok(layout) => layout,
1024 Err(ty::layout::LayoutError::Unknown(_)) => return,
1025 Err(err @ ty::layout::LayoutError::SizeOverflow(_)) => {
1026 bug!("failed to get layout for `{}`: {}", t, err);
1029 let (variants, tag) = match layout.variants {
1030 layout::Variants::Multiple {
1031 discr_kind: layout::DiscriminantKind::Tag,
1035 } => (variants, discr),
1039 let discr_size = tag.value.size(&cx.tcx).bytes();
1041 debug!("enum `{}` is {} bytes large with layout:\n{:#?}",
1042 t, layout.size.bytes(), layout);
1044 let (largest, slargest, largest_index) = enum_definition.variants
1047 .map(|(variant, variant_layout)| {
1048 // Subtract the size of the enum discriminant.
1049 let bytes = variant_layout.size.bytes().saturating_sub(discr_size);
1051 debug!("- variant `{}` is {} bytes large",
1057 .fold((0, 0, 0), |(l, s, li), (idx, size)| if size > l {
1059 } else if size > s {
1065 // We only warn if the largest variant is at least thrice as large as
1066 // the second-largest.
1067 if largest > slargest * 3 && slargest > 0 {
1068 cx.span_lint(VARIANT_SIZE_DIFFERENCES,
1069 enum_definition.variants[largest_index].span,
1070 &format!("enum variant is more than three times \
1071 larger ({} bytes) than the next largest",