1 // Copyright 2012-2015 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 #![allow(non_snake_case)]
13 use rustc::hir::def_id::DefId;
14 use rustc::ty::subst::Substs;
15 use rustc::ty::{self, AdtKind, Ty, TyCtxt};
16 use rustc::ty::layout::{self, LayoutOf};
17 use middle::const_val::ConstVal;
18 use rustc_const_eval::ConstContext;
19 use util::nodemap::FxHashSet;
20 use lint::{LateContext, LintContext, LintArray};
21 use lint::{LintPass, LateLintPass};
24 use std::{i8, i16, i32, i64, u8, u16, u32, u64, f32, f64};
37 "comparisons made useless by limits of the types involved"
43 "literal out of range for its type"
49 "shift exceeds the type's number of bits"
53 VARIANT_SIZE_DIFFERENCES,
55 "detects enums with widely varying variant sizes"
58 #[derive(Copy, Clone)]
59 pub struct TypeLimits {
60 /// Id of the last visited negated expression
61 negated_expr_id: ast::NodeId,
65 pub fn new() -> TypeLimits {
66 TypeLimits { negated_expr_id: ast::DUMMY_NODE_ID }
70 impl LintPass for TypeLimits {
71 fn get_lints(&self) -> LintArray {
72 lint_array!(UNUSED_COMPARISONS,
78 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
79 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx hir::Expr) {
81 hir::ExprUnary(hir::UnNeg, ref expr) => {
82 // propagate negation, if the negation itself isn't negated
83 if self.negated_expr_id != e.id {
84 self.negated_expr_id = expr.id;
87 hir::ExprBinary(binop, ref l, ref r) => {
88 if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
89 cx.span_lint(UNUSED_COMPARISONS,
91 "comparison is useless due to type limits");
94 if binop.node.is_shift() {
95 let opt_ty_bits = match cx.tables.node_id_to_type(l.hir_id).sty {
96 ty::TyInt(t) => Some(int_ty_bits(t, cx.sess().target.isize_ty)),
97 ty::TyUint(t) => Some(uint_ty_bits(t, cx.sess().target.usize_ty)),
101 if let Some(bits) = opt_ty_bits {
102 let exceeding = if let hir::ExprLit(ref lit) = r.node {
103 if let ast::LitKind::Int(shift, _) = lit.node {
109 // HACK(eddyb) This might be quite inefficient.
110 // This would be better left to MIR constant propagation,
111 // perhaps even at trans time (like is the case already
112 // when the value being shifted is *also* constant).
113 let parent_item = cx.tcx.hir.get_parent(e.id);
114 let parent_def_id = cx.tcx.hir.local_def_id(parent_item);
115 let substs = Substs::identity_for_item(cx.tcx, parent_def_id);
116 let const_cx = ConstContext::new(cx.tcx,
117 cx.param_env.and(substs),
119 match const_cx.eval(&r) {
120 Ok(&ty::Const { val: ConstVal::Integral(i), .. }) => {
130 cx.span_lint(EXCEEDING_BITSHIFTS,
132 "bitshift exceeds the type's number of bits");
137 hir::ExprLit(ref lit) => {
138 match cx.tables.node_id_to_type(e.hir_id).sty {
141 ast::LitKind::Int(v, ast::LitIntType::Signed(_)) |
142 ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => {
143 let int_type = if let ast::IntTy::Isize = t {
144 cx.sess().target.isize_ty
148 let (_, max) = int_ty_range(int_type);
149 let max = max as u128;
150 let negative = self.negated_expr_id == e.id;
152 // Detect literal value out of range [min, max] inclusive
153 // avoiding use of -min to prevent overflow/panic
154 if (negative && v > max + 1) ||
155 (!negative && v > max) {
156 cx.span_lint(OVERFLOWING_LITERALS,
158 &format!("literal out of range for {:?}", t));
166 let uint_type = if let ast::UintTy::Usize = t {
167 cx.sess().target.usize_ty
171 let (min, max) = uint_ty_range(uint_type);
172 let lit_val: u128 = match lit.node {
173 // _v is u8, within range by definition
174 ast::LitKind::Byte(_v) => return,
175 ast::LitKind::Int(v, _) => v,
178 if lit_val < min || lit_val > max {
179 cx.span_lint(OVERFLOWING_LITERALS,
181 &format!("literal out of range for {:?}", t));
185 let is_infinite = match lit.node {
186 ast::LitKind::Float(v, _) |
187 ast::LitKind::FloatUnsuffixed(v) => {
189 ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite),
190 ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite),
195 if is_infinite == Ok(true) {
196 cx.span_lint(OVERFLOWING_LITERALS,
198 &format!("literal out of range for {:?}", t));
207 fn is_valid<T: cmp::PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool {
209 hir::BiLt => v > min && v <= max,
210 hir::BiLe => v >= min && v < max,
211 hir::BiGt => v >= min && v < max,
212 hir::BiGe => v > min && v <= max,
213 hir::BiEq | hir::BiNe => v >= min && v <= max,
218 fn rev_binop(binop: hir::BinOp) -> hir::BinOp {
219 codemap::respan(binop.span,
221 hir::BiLt => hir::BiGt,
222 hir::BiLe => hir::BiGe,
223 hir::BiGt => hir::BiLt,
224 hir::BiGe => hir::BiLe,
229 // for isize & usize, be conservative with the warnings, so that the
230 // warnings are consistent between 32- and 64-bit platforms
231 fn int_ty_range(int_ty: ast::IntTy) -> (i128, i128) {
233 ast::IntTy::Isize => (i64::min_value() as i128, i64::max_value() as i128),
234 ast::IntTy::I8 => (i8::min_value() as i64 as i128, i8::max_value() as i128),
235 ast::IntTy::I16 => (i16::min_value() as i64 as i128, i16::max_value() as i128),
236 ast::IntTy::I32 => (i32::min_value() as i64 as i128, i32::max_value() as i128),
237 ast::IntTy::I64 => (i64::min_value() as i128, i64::max_value() as i128),
238 ast::IntTy::I128 =>(i128::min_value() as i128, i128::max_value()),
242 fn uint_ty_range(uint_ty: ast::UintTy) -> (u128, u128) {
244 ast::UintTy::Usize => (u64::min_value() as u128, u64::max_value() as u128),
245 ast::UintTy::U8 => (u8::min_value() as u128, u8::max_value() as u128),
246 ast::UintTy::U16 => (u16::min_value() as u128, u16::max_value() as u128),
247 ast::UintTy::U32 => (u32::min_value() as u128, u32::max_value() as u128),
248 ast::UintTy::U64 => (u64::min_value() as u128, u64::max_value() as u128),
249 ast::UintTy::U128 => (u128::min_value(), u128::max_value()),
253 fn int_ty_bits(int_ty: ast::IntTy, isize_ty: ast::IntTy) -> u64 {
255 ast::IntTy::Isize => int_ty_bits(isize_ty, isize_ty),
257 ast::IntTy::I16 => 16 as u64,
258 ast::IntTy::I32 => 32,
259 ast::IntTy::I64 => 64,
260 ast::IntTy::I128 => 128,
264 fn uint_ty_bits(uint_ty: ast::UintTy, usize_ty: ast::UintTy) -> u64 {
266 ast::UintTy::Usize => uint_ty_bits(usize_ty, usize_ty),
267 ast::UintTy::U8 => 8,
268 ast::UintTy::U16 => 16,
269 ast::UintTy::U32 => 32,
270 ast::UintTy::U64 => 64,
271 ast::UintTy::U128 => 128,
275 fn check_limits(cx: &LateContext,
280 let (lit, expr, swap) = match (&l.node, &r.node) {
281 (&hir::ExprLit(_), _) => (l, r, true),
282 (_, &hir::ExprLit(_)) => (r, l, false),
285 // Normalize the binop so that the literal is always on the RHS in
287 let norm_binop = if swap { rev_binop(binop) } else { binop };
288 match cx.tables.node_id_to_type(expr.hir_id).sty {
289 ty::TyInt(int_ty) => {
290 let (min, max) = int_ty_range(int_ty);
291 let lit_val: i128 = match lit.node {
292 hir::ExprLit(ref li) => {
294 ast::LitKind::Int(v, ast::LitIntType::Signed(_)) |
295 ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => v as i128,
301 is_valid(norm_binop, lit_val, min, max)
303 ty::TyUint(uint_ty) => {
304 let (min, max) :(u128, u128) = uint_ty_range(uint_ty);
305 let lit_val: u128 = match lit.node {
306 hir::ExprLit(ref li) => {
308 ast::LitKind::Int(v, _) => v,
314 is_valid(norm_binop, lit_val, min, max)
320 fn is_comparison(binop: hir::BinOp) -> bool {
322 hir::BiEq | hir::BiLt | hir::BiLe | hir::BiNe | hir::BiGe | hir::BiGt => true,
332 "proper use of libc types in foreign modules"
335 struct ImproperCTypesVisitor<'a, 'tcx: 'a> {
336 cx: &'a LateContext<'a, 'tcx>,
342 FfiUnsafe(&'static str),
343 FfiBadStruct(DefId, &'static str),
344 FfiBadUnion(DefId, &'static str),
345 FfiBadEnum(DefId, &'static str),
348 /// Check if this enum can be safely exported based on the
349 /// "nullable pointer optimization". Currently restricted
350 /// to function pointers and references, but could be
351 /// expanded to cover NonZero raw pointers and newtypes.
352 /// FIXME: This duplicates code in trans.
353 fn is_repr_nullable_ptr<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
354 def: &'tcx ty::AdtDef,
355 substs: &Substs<'tcx>)
357 if def.variants.len() == 2 {
360 if def.variants[0].fields.is_empty() {
362 } else if def.variants[1].fields.is_empty() {
368 if def.variants[data_idx].fields.len() == 1 {
369 match def.variants[data_idx].fields[0].ty(tcx, substs).sty {
383 fn is_ffi_safe(ty: attr::IntType) -> bool {
385 attr::SignedInt(ast::IntTy::I8) | attr::UnsignedInt(ast::UintTy::U8) |
386 attr::SignedInt(ast::IntTy::I16) | attr::UnsignedInt(ast::UintTy::U16) |
387 attr::SignedInt(ast::IntTy::I32) | attr::UnsignedInt(ast::UintTy::U32) |
388 attr::SignedInt(ast::IntTy::I64) | attr::UnsignedInt(ast::UintTy::U64) |
389 attr::SignedInt(ast::IntTy::I128) | attr::UnsignedInt(ast::UintTy::U128) => true,
390 attr::SignedInt(ast::IntTy::Isize) | attr::UnsignedInt(ast::UintTy::Usize) => false
394 impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
395 /// Check if the given type is "ffi-safe" (has a stable, well-defined
396 /// representation which can be exported to C code).
397 fn check_type_for_ffi(&self,
398 cache: &mut FxHashSet<Ty<'tcx>>,
399 ty: Ty<'tcx>) -> FfiResult {
400 use self::FfiResult::*;
402 let cx = self.cx.tcx;
404 // Protect against infinite recursion, for example
405 // `struct S(*mut S);`.
406 // FIXME: A recursion limit is necessary as well, for irregular
408 if !cache.insert(ty) {
413 ty::TyAdt(def, substs) => {
414 if def.is_phantom_data() {
417 match def.adt_kind() {
419 if !def.repr.c() && !def.repr.transparent() {
420 return FfiUnsafe("found struct without foreign-function-safe \
421 representation annotation in foreign module, \
422 consider adding a #[repr(C)] attribute to the type");
425 if def.non_enum_variant().fields.is_empty() {
426 return FfiUnsafe("found zero-size struct in foreign module, consider \
427 adding a member to this struct");
430 // We can't completely trust repr(C) and repr(transparent) markings;
431 // make sure the fields are actually safe.
432 let mut all_phantom = true;
433 for field in &def.non_enum_variant().fields {
434 let field_ty = cx.fully_normalize_associated_types_in(
435 &field.ty(cx, substs)
437 // repr(transparent) types are allowed to have arbitrary ZSTs, not just
438 // PhantomData -- skip checking all ZST fields
439 if def.repr.transparent() {
440 let is_zst = (cx, cx.param_env(field.did))
442 .map(|layout| layout.is_zst())
448 let r = self.check_type_for_ffi(cache, field_ty);
454 FfiBadStruct(..) | FfiBadUnion(..) | FfiBadEnum(..) => {
458 return FfiBadStruct(def.did, s);
463 if all_phantom { FfiPhantom } else { FfiSafe }
467 return FfiUnsafe("found union without foreign-function-safe \
468 representation annotation in foreign module, \
469 consider adding a #[repr(C)] attribute to the type");
472 if def.non_enum_variant().fields.is_empty() {
473 return FfiUnsafe("found zero-size union in foreign module, consider \
474 adding a member to this union");
477 let mut all_phantom = true;
478 for field in &def.non_enum_variant().fields {
479 let field_ty = cx.fully_normalize_associated_types_in(
480 &field.ty(cx, substs)
482 let r = self.check_type_for_ffi(cache, field_ty);
488 FfiBadStruct(..) | FfiBadUnion(..) | FfiBadEnum(..) => {
492 return FfiBadUnion(def.did, s);
497 if all_phantom { FfiPhantom } else { FfiSafe }
500 if def.variants.is_empty() {
501 // Empty enums are okay... although sort of useless.
505 // Check for a repr() attribute to specify the size of the
507 if !def.repr.c() && def.repr.int.is_none() {
508 // Special-case types like `Option<extern fn()>`.
509 if !is_repr_nullable_ptr(cx, def, substs) {
510 return FfiUnsafe("found enum without foreign-function-safe \
511 representation annotation in foreign \
512 module, consider adding a #[repr(...)] \
513 attribute to the type");
517 if let Some(int_ty) = def.repr.int {
518 if !is_ffi_safe(int_ty) {
519 // FIXME: This shouldn't be reachable: we should check
521 return FfiUnsafe("enum has unexpected #[repr(...)] attribute");
524 // Enum with an explicitly sized discriminant; either
525 // a C-style enum or a discriminated union.
527 // The layout of enum variants is implicitly repr(C).
528 // FIXME: Is that correct?
531 // Check the contained variants.
532 for variant in &def.variants {
533 for field in &variant.fields {
534 let arg = cx.fully_normalize_associated_types_in(
535 &field.ty(cx, substs)
537 let r = self.check_type_for_ffi(cache, arg);
540 FfiBadStruct(..) | FfiBadUnion(..) | FfiBadEnum(..) => {
544 return FfiBadEnum(def.did,
545 "Found phantom data in enum variant");
548 return FfiBadEnum(def.did, s);
559 FfiUnsafe("found Rust type `char` in foreign module, while \
560 `u32` or `libc::wchar_t` should be used")
563 ty::TyInt(ast::IntTy::I128) => {
564 FfiUnsafe("found Rust type `i128` in foreign module, but \
565 128-bit integers don't currently have a known \
569 ty::TyUint(ast::UintTy::U128) => {
570 FfiUnsafe("found Rust type `u128` in foreign module, but \
571 128-bit integers don't currently have a known \
575 // Primitive types with a stable representation.
576 ty::TyBool | ty::TyInt(..) | ty::TyUint(..) | ty::TyFloat(..) | ty::TyNever => FfiSafe,
579 FfiUnsafe("found Rust slice type in foreign module, \
580 consider using a raw pointer instead")
583 ty::TyDynamic(..) => {
584 FfiUnsafe("found Rust trait type in foreign module, \
585 consider using a raw pointer instead")
589 FfiUnsafe("found Rust type `str` in foreign module; \
590 consider using a `*const libc::c_char`")
594 FfiUnsafe("found Rust tuple type in foreign module; \
595 consider using a struct instead")
598 ty::TyRawPtr(ref m) |
599 ty::TyRef(_, ref m) => self.check_type_for_ffi(cache, m.ty),
601 ty::TyArray(ty, _) => self.check_type_for_ffi(cache, ty),
603 ty::TyFnPtr(sig) => {
605 Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic | Abi::RustCall => {
606 return FfiUnsafe("found function pointer with Rust calling convention in \
607 foreign module; consider using an `extern` function \
613 let sig = cx.erase_late_bound_regions(&sig);
614 if !sig.output().is_nil() {
615 let r = self.check_type_for_ffi(cache, sig.output());
623 for arg in sig.inputs() {
624 let r = self.check_type_for_ffi(cache, arg);
635 ty::TyForeign(..) => FfiSafe,
641 ty::TyGenerator(..) |
642 ty::TyGeneratorWitness(..) |
643 ty::TyProjection(..) |
645 ty::TyFnDef(..) => bug!("Unexpected type in foreign function"),
649 fn check_type_for_ffi_and_report_errors(&mut self, sp: Span, ty: Ty<'tcx>) {
650 // it is only OK to use this function because extern fns cannot have
651 // any generic types right now:
652 let ty = self.cx.tcx.fully_normalize_associated_types_in(&ty);
654 match self.check_type_for_ffi(&mut FxHashSet(), ty) {
655 FfiResult::FfiSafe => {}
656 FfiResult::FfiPhantom => {
657 self.cx.span_lint(IMPROPER_CTYPES,
659 &format!("found zero-sized type composed only \
660 of phantom-data in a foreign-function."));
662 FfiResult::FfiUnsafe(s) => {
663 self.cx.span_lint(IMPROPER_CTYPES, sp, s);
665 FfiResult::FfiBadStruct(_, s) => {
666 // FIXME: This diagnostic is difficult to read, and doesn't
667 // point at the relevant field.
668 self.cx.span_lint(IMPROPER_CTYPES,
670 &format!("found non-foreign-function-safe member in struct \
671 marked #[repr(C)]: {}",
674 FfiResult::FfiBadUnion(_, s) => {
675 // FIXME: This diagnostic is difficult to read, and doesn't
676 // point at the relevant field.
677 self.cx.span_lint(IMPROPER_CTYPES,
679 &format!("found non-foreign-function-safe member in union \
680 marked #[repr(C)]: {}",
683 FfiResult::FfiBadEnum(_, s) => {
684 // FIXME: This diagnostic is difficult to read, and doesn't
685 // point at the relevant variant.
686 self.cx.span_lint(IMPROPER_CTYPES,
688 &format!("found non-foreign-function-safe member in enum: {}",
694 fn check_foreign_fn(&mut self, id: ast::NodeId, decl: &hir::FnDecl) {
695 let def_id = self.cx.tcx.hir.local_def_id(id);
696 let sig = self.cx.tcx.fn_sig(def_id);
697 let sig = self.cx.tcx.erase_late_bound_regions(&sig);
699 for (input_ty, input_hir) in sig.inputs().iter().zip(&decl.inputs) {
700 self.check_type_for_ffi_and_report_errors(input_hir.span, input_ty);
703 if let hir::Return(ref ret_hir) = decl.output {
704 let ret_ty = sig.output();
705 if !ret_ty.is_nil() {
706 self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty);
711 fn check_foreign_static(&mut self, id: ast::NodeId, span: Span) {
712 let def_id = self.cx.tcx.hir.local_def_id(id);
713 let ty = self.cx.tcx.type_of(def_id);
714 self.check_type_for_ffi_and_report_errors(span, ty);
718 #[derive(Copy, Clone)]
719 pub struct ImproperCTypes;
721 impl LintPass for ImproperCTypes {
722 fn get_lints(&self) -> LintArray {
723 lint_array!(IMPROPER_CTYPES)
727 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImproperCTypes {
728 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
729 let mut vis = ImproperCTypesVisitor { cx: cx };
730 if let hir::ItemForeignMod(ref nmod) = it.node {
731 if nmod.abi != Abi::RustIntrinsic && nmod.abi != Abi::PlatformIntrinsic {
732 for ni in &nmod.items {
734 hir::ForeignItemFn(ref decl, _, _) => {
735 vis.check_foreign_fn(ni.id, decl);
737 hir::ForeignItemStatic(ref ty, _) => {
738 vis.check_foreign_static(ni.id, ty.span);
740 hir::ForeignItemType => ()
748 pub struct VariantSizeDifferences;
750 impl LintPass for VariantSizeDifferences {
751 fn get_lints(&self) -> LintArray {
752 lint_array!(VARIANT_SIZE_DIFFERENCES)
756 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for VariantSizeDifferences {
757 fn check_item(&mut self, cx: &LateContext, it: &hir::Item) {
758 if let hir::ItemEnum(ref enum_definition, ref gens) = it.node {
759 if gens.params.iter().all(|param| param.is_lifetime_param()) {
760 // sizes only make sense for non-generic types
761 let item_def_id = cx.tcx.hir.local_def_id(it.id);
762 let t = cx.tcx.type_of(item_def_id);
763 let ty = cx.tcx.erase_regions(&t);
764 let layout = cx.layout_of(ty).unwrap_or_else(|e| {
765 bug!("failed to get layout for `{}`: {}", t, e)
768 if let layout::Variants::Tagged { ref variants, ref discr, .. } = layout.variants {
769 let discr_size = discr.value.size(cx.tcx).bytes();
771 debug!("enum `{}` is {} bytes large with layout:\n{:#?}",
772 t, layout.size.bytes(), layout);
774 let (largest, slargest, largest_index) = enum_definition.variants
777 .map(|(variant, variant_layout)| {
778 // Subtract the size of the enum discriminant
779 let bytes = variant_layout.size.bytes()
780 .saturating_sub(discr_size);
782 debug!("- variant `{}` is {} bytes large", variant.node.name, bytes);
786 .fold((0, 0, 0), |(l, s, li), (idx, size)| if size > l {
794 // we only warn if the largest variant is at least thrice as large as
795 // the second-largest.
796 if largest > slargest * 3 && slargest > 0 {
797 cx.span_lint(VARIANT_SIZE_DIFFERENCES,
798 enum_definition.variants[largest_index].span,
799 &format!("enum variant is more than three times larger \
800 ({} bytes) than the next largest",