| #![allow(non_snake_case)] |
| |
| use crate::{LateContext, LateLintPass, LintContext}; |
| use rustc_ast::ast; |
| use rustc_attr as attr; |
| use rustc_data_structures::fx::FxHashSet; |
| use rustc_errors::Applicability; |
| use rustc_hir as hir; |
| use rustc_hir::{is_range_literal, ExprKind, Node}; |
| use rustc_index::vec::Idx; |
| use rustc_middle::mir::interpret::{sign_extend, truncate}; |
| use rustc_middle::ty::layout::{IntegerExt, SizeSkeleton}; |
| use rustc_middle::ty::subst::SubstsRef; |
| use rustc_middle::ty::{self, AdtKind, Ty, TypeFoldable}; |
| use rustc_span::source_map; |
| use rustc_span::symbol::sym; |
| use rustc_span::{Span, DUMMY_SP}; |
| use rustc_target::abi::{Integer, LayoutOf, TagEncoding, VariantIdx, Variants}; |
| use rustc_target::spec::abi::Abi; |
| |
| use log::debug; |
| use std::cmp; |
| |
| declare_lint! { |
| UNUSED_COMPARISONS, |
| Warn, |
| "comparisons made useless by limits of the types involved" |
| } |
| |
| declare_lint! { |
| OVERFLOWING_LITERALS, |
| Deny, |
| "literal out of range for its type" |
| } |
| |
| declare_lint! { |
| 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. |
| /// Returns `true` iff the lint was overridden. |
| fn lint_overflowing_range_endpoint<'tcx>( |
| cx: &LateContext<'tcx>, |
| lit: &hir::Lit, |
| lit_val: u128, |
| max: u128, |
| expr: &'tcx hir::Expr<'tcx>, |
| parent_expr: &'tcx hir::Expr<'tcx>, |
| ty: &str, |
| ) -> bool { |
| // We only want to handle exclusive (`..`) ranges, |
| // which are represented as `ExprKind::Struct`. |
| let mut overwritten = false; |
| if let ExprKind::Struct(_, eps, _) = &parent_expr.kind { |
| 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 { |
| cx.struct_span_lint(OVERFLOWING_LITERALS, parent_expr.span, |lint| { |
| let mut err = lint.build(&format!("range endpoint is out of range for `{}`", ty)); |
| if let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) { |
| use ast::{LitIntType, LitKind}; |
| // We need to preserve the literal's suffix, |
| // as it may determine typing information. |
| let suffix = match lit.node { |
| LitKind::Int(_, LitIntType::Signed(s)) => s.name_str().to_string(), |
| LitKind::Int(_, LitIntType::Unsigned(s)) => s.name_str().to_string(), |
| LitKind::Int(_, LitIntType::Unsuffixed) => "".to_string(), |
| _ => bug!(), |
| }; |
| let suggestion = format!("{}..={}{}", start, lit_val - 1, suffix); |
| err.span_suggestion( |
| parent_expr.span, |
| &"use an inclusive range instead", |
| suggestion, |
| Applicability::MachineApplicable, |
| ); |
| err.emit(); |
| overwritten = true; |
| } |
| }); |
| } |
| } |
| overwritten |
| } |
| |
| // 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: ast::IntTy) -> (i128, i128) { |
| match int_ty { |
| ast::IntTy::Isize => (i64::MIN as i128, i64::MAX as i128), |
| ast::IntTy::I8 => (i8::MIN as i64 as i128, i8::MAX as i128), |
| ast::IntTy::I16 => (i16::MIN as i64 as i128, i16::MAX as i128), |
| ast::IntTy::I32 => (i32::MIN as i64 as i128, i32::MAX as i128), |
| ast::IntTy::I64 => (i64::MIN as i128, i64::MAX as i128), |
| ast::IntTy::I128 => (i128::MIN as i128, i128::MAX), |
| } |
| } |
| |
| fn uint_ty_range(uint_ty: ast::UintTy) -> (u128, u128) { |
| match uint_ty { |
| ast::UintTy::Usize => (u64::MIN as u128, u64::MAX as u128), |
| ast::UintTy::U8 => (u8::MIN as u128, u8::MAX as u128), |
| ast::UintTy::U16 => (u16::MIN as u128, u16::MAX as u128), |
| ast::UintTy::U32 => (u32::MIN as u128, u32::MAX as u128), |
| ast::UintTy::U64 => (u64::MIN as u128, u64::MAX as u128), |
| ast::UintTy::U128 => (u128::MIN, u128::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, |
| repr_str: String, |
| val: u128, |
| negative: bool, |
| ) { |
| let size = Integer::from_attr(&cx.tcx, ty).size(); |
| cx.struct_span_lint(OVERFLOWING_LITERALS, expr.span, |lint| { |
| let (t, actually) = match ty { |
| attr::IntType::SignedInt(t) => { |
| let actually = sign_extend(val, size) as i128; |
| (t.name_str(), actually.to_string()) |
| } |
| attr::IntType::UnsignedInt(t) => { |
| let actually = truncate(val, size); |
| (t.name_str(), actually.to_string()) |
| } |
| }; |
| let mut err = lint.build(&format!("literal out of range for {}", t)); |
| err.note(&format!( |
| "the literal `{}` (decimal `{}`) does not fit into \ |
| the type `{}` and will become `{}{}`", |
| repr_str, val, t, actually, t |
| )); |
| if let Some(sugg_ty) = |
| get_type_suggestion(&cx.tables().node_type(expr.hir_id), val, negative) |
| { |
| if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') { |
| let (sans_suffix, _) = repr_str.split_at(pos); |
| err.span_suggestion( |
| expr.span, |
| &format!("consider using `{}` instead", sugg_ty), |
| format!("{}{}", sans_suffix, sugg_ty), |
| Applicability::MachineApplicable, |
| ); |
| } else { |
| err.help(&format!("consider using `{}` instead", sugg_ty)); |
| } |
| } |
| err.emit(); |
| }); |
| } |
| |
| // 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 rustc_ast::ast::IntTy::*; |
| use rustc_ast::ast::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: ast::IntTy, |
| v: u128, |
| ) { |
| let int_type = t.normalize(cx.sess().target.ptr_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(t), repr_str, v, negative); |
| return; |
| } |
| |
| let par_id = cx.tcx.hir().get_parent_node(e.hir_id); |
| if let Node::Expr(par_e) = cx.tcx.hir().get(par_id) { |
| if let hir::ExprKind::Struct(..) = par_e.kind { |
| if is_range_literal(cx.sess().source_map(), par_e) |
| && lint_overflowing_range_endpoint(cx, lit, v, max, e, par_e, t.name_str()) |
| { |
| // The overflowing literal lint was overridden. |
| return; |
| } |
| } |
| } |
| |
| cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
| lint.build(&format!("literal out of range for `{}`", t.name_str())) |
| .note(&format!( |
| "the literal `{}` does not fit into the type `{}` whose range is `{}..={}`", |
| cx.sess() |
| .source_map() |
| .span_to_snippet(lit.span) |
| .expect("must get snippet from literal"), |
| t.name_str(), |
| min, |
| max, |
| )) |
| .emit(); |
| }); |
| } |
| } |
| |
| fn lint_uint_literal<'tcx>( |
| cx: &LateContext<'tcx>, |
| e: &'tcx hir::Expr<'tcx>, |
| lit: &hir::Lit, |
| t: ast::UintTy, |
| ) { |
| let uint_type = t.normalize(cx.sess().target.ptr_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().get_parent_node(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.tables().expr_ty(par_e).kind { |
| cx.struct_span_lint(OVERFLOWING_LITERALS, par_e.span, |lint| { |
| lint.build("only `u8` can be cast into `char`") |
| .span_suggestion( |
| par_e.span, |
| &"use a `char` literal instead", |
| format!("'\\u{{{:X}}}'", lit_val), |
| Applicability::MachineApplicable, |
| ) |
| .emit(); |
| }); |
| return; |
| } |
| } |
| hir::ExprKind::Struct(..) if is_range_literal(cx.sess().source_map(), par_e) => { |
| let t = t.name_str(); |
| if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, par_e, t) { |
| // The overflowing literal lint was overridden. |
| return; |
| } |
| } |
| _ => {} |
| } |
| } |
| if let Some(repr_str) = get_bin_hex_repr(cx, lit) { |
| report_bin_hex_error(cx, e, attr::IntType::UnsignedInt(t), repr_str, lit_val, false); |
| return; |
| } |
| cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
| lint.build(&format!("literal out of range for `{}`", t.name_str())) |
| .note(&format!( |
| "the literal `{}` does not fit into the type `{}` whose range is `{}..={}`", |
| cx.sess() |
| .source_map() |
| .span_to_snippet(lit.span) |
| .expect("must get snippet from literal"), |
| t.name_str(), |
| min, |
| max, |
| )) |
| .emit() |
| }); |
| } |
| } |
| |
| fn lint_literal<'tcx>( |
| cx: &LateContext<'tcx>, |
| type_limits: &TypeLimits, |
| e: &'tcx hir::Expr<'tcx>, |
| lit: &hir::Lit, |
| ) { |
| match cx.tables().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 { |
| ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite), |
| ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite), |
| }, |
| _ => bug!(), |
| }; |
| if is_infinite == Ok(true) { |
| cx.struct_span_lint(OVERFLOWING_LITERALS, e.span, |lint| { |
| lint.build(&format!("literal out of range for `{}`", t.name_str())) |
| .note(&format!( |
| "the literal `{}` does not fit into the type `{}` and will be converted to `std::{}::INFINITY`", |
| cx.sess() |
| .source_map() |
| .span_to_snippet(lit.span) |
| .expect("must get snippet from literal"), |
| t.name_str(), |
| t.name_str(), |
| )) |
| .emit(); |
| }); |
| } |
| } |
| _ => {} |
| } |
| } |
| |
| 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::UnNeg, 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.struct_span_lint(UNUSED_COMPARISONS, e.span, |lint| { |
| lint.build("comparison is useless due to type limits").emit() |
| }); |
| } |
| } |
| hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit), |
| _ => {} |
| }; |
| |
| fn is_valid<T: cmp::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.tables().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 { |
| match binop.node { |
| hir::BinOpKind::Eq |
| | hir::BinOpKind::Lt |
| | hir::BinOpKind::Le |
| | hir::BinOpKind::Ne |
| | hir::BinOpKind::Ge |
| | hir::BinOpKind::Gt => true, |
| _ => false, |
| } |
| } |
| } |
| } |
| |
| declare_lint! { |
| IMPROPER_CTYPES, |
| Warn, |
| "proper use of libc types in foreign modules" |
| } |
| |
| declare_lint_pass!(ImproperCTypesDeclarations => [IMPROPER_CTYPES]); |
| |
| declare_lint! { |
| IMPROPER_CTYPES_DEFINITIONS, |
| Warn, |
| "proper use of libc types in foreign item definitions" |
| } |
| |
| declare_lint_pass!(ImproperCTypesDefinitions => [IMPROPER_CTYPES_DEFINITIONS]); |
| |
| enum ImproperCTypesMode { |
| Declarations, |
| Definitions, |
| } |
| |
| struct ImproperCTypesVisitor<'a, 'tcx> { |
| cx: &'a LateContext<'tcx>, |
| mode: ImproperCTypesMode, |
| } |
| |
| enum FfiResult<'tcx> { |
| FfiSafe, |
| FfiPhantom(Ty<'tcx>), |
| FfiUnsafe { ty: Ty<'tcx>, reason: String, help: Option<String> }, |
| } |
| |
| impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> { |
| /// Is type known to be non-null? |
| fn ty_is_known_nonnull(&self, ty: Ty<'tcx>) -> bool { |
| match ty.kind { |
| ty::FnPtr(_) => true, |
| ty::Ref(..) => true, |
| ty::Adt(field_def, substs) if field_def.repr.transparent() && !field_def.is_union() => { |
| for field in field_def.all_fields() { |
| let field_ty = self.cx.tcx.normalize_erasing_regions( |
| self.cx.param_env, |
| field.ty(self.cx.tcx, substs), |
| ); |
| if field_ty.is_zst(self.cx.tcx, field.did) { |
| continue; |
| } |
| |
| let attrs = self.cx.tcx.get_attrs(field_def.did); |
| if attrs |
| .iter() |
| .any(|a| a.check_name(sym::rustc_nonnull_optimization_guaranteed)) |
| || self.ty_is_known_nonnull(field_ty) |
| { |
| return true; |
| } |
| } |
| |
| false |
| } |
| _ => false, |
| } |
| } |
| |
| /// Check if this enum can be safely exported based on the "nullable pointer optimization". |
| /// Currently restricted to function pointers, references, `core::num::NonZero*`, |
| /// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes. |
| fn is_repr_nullable_ptr( |
| &self, |
| ty: Ty<'tcx>, |
| ty_def: &'tcx ty::AdtDef, |
| substs: SubstsRef<'tcx>, |
| ) -> bool { |
| if ty_def.variants.len() != 2 { |
| return false; |
| } |
| |
| let get_variant_fields = |index| &ty_def.variants[VariantIdx::new(index)].fields; |
| let variant_fields = [get_variant_fields(0), get_variant_fields(1)]; |
| let fields = if variant_fields[0].is_empty() { |
| &variant_fields[1] |
| } else if variant_fields[1].is_empty() { |
| &variant_fields[0] |
| } else { |
| return false; |
| }; |
| |
| if fields.len() != 1 { |
| return false; |
| } |
| |
| let field_ty = fields[0].ty(self.cx.tcx, substs); |
| if !self.ty_is_known_nonnull(field_ty) { |
| return false; |
| } |
| |
| // 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 non-null |
| // optimization isn't being applied (and we've got a problem somewhere). |
| let compute_size_skeleton = |
| |t| SizeSkeleton::compute(t, self.cx.tcx, self.cx.param_env).unwrap(); |
| if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) { |
| bug!("improper_ctypes: Option nonnull optimization not applied?"); |
| } |
| |
| true |
| } |
| |
| /// 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, |
| "passing raw arrays by value is not FFI-safe", |
| Some("consider passing a pointer to the array"), |
| ); |
| 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, |
| variant: &ty::VariantDef, |
| substs: SubstsRef<'tcx>, |
| ) -> FfiResult<'tcx> { |
| use FfiResult::*; |
| |
| if def.repr.transparent() { |
| // Can assume that only one field is not a ZST, so only check |
| // that field's type for FFI-safety. |
| if let Some(field) = variant.transparent_newtype_field(self.cx.tcx) { |
| self.check_field_type_for_ffi(cache, field, substs) |
| } else { |
| bug!("malformed transparent type"); |
| } |
| } else { |
| // 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.is_enum() => { |
| return FfiUnsafe { |
| ty, |
| reason: "this enum contains a PhantomData field".into(), |
| help: None, |
| }; |
| } |
| FfiPhantom(..) => {} |
| r => return r, |
| } |
| } |
| |
| if all_phantom { FfiPhantom(ty) } else { 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 cx = 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_phantom_data() { |
| return FfiPhantom(ty); |
| } |
| match def.adt_kind() { |
| AdtKind::Struct | AdtKind::Union => { |
| let kind = if def.is_struct() { "struct" } else { "union" }; |
| |
| if !def.repr.c() && !def.repr.transparent() { |
| return FfiUnsafe { |
| ty, |
| reason: format!("this {} has unspecified layout", kind), |
| help: Some(format!( |
| "consider adding a `#[repr(C)]` or \ |
| `#[repr(transparent)]` attribute to this {}", |
| kind |
| )), |
| }; |
| } |
| |
| 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: format!("this {} is non-exhaustive", kind), |
| help: None, |
| }; |
| } |
| |
| if def.non_enum_variant().fields.is_empty() { |
| return FfiUnsafe { |
| ty, |
| reason: format!("this {} has no fields", kind), |
| help: Some(format!("consider adding a member to this {}", kind)), |
| }; |
| } |
| |
| 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 !self.is_repr_nullable_ptr(ty, def, substs) { |
| return FfiUnsafe { |
| ty, |
| reason: "enum has no representation hint".into(), |
| help: Some( |
| "consider adding a `#[repr(C)]`, \ |
| `#[repr(transparent)]`, or integer `#[repr(...)]` \ |
| attribute to this enum" |
| .into(), |
| ), |
| }; |
| } |
| } |
| |
| if def.is_variant_list_non_exhaustive() && !def.did.is_local() { |
| return FfiUnsafe { |
| ty, |
| reason: "this enum is non-exhaustive".into(), |
| 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: "this enum has non-exhaustive variants".into(), |
| help: None, |
| }; |
| } |
| |
| match self.check_variant_for_ffi(cache, ty, def, variant, substs) { |
| FfiSafe => (), |
| r => return r, |
| } |
| } |
| |
| FfiSafe |
| } |
| } |
| } |
| |
| ty::Char => FfiUnsafe { |
| ty, |
| reason: "the `char` type has no C equivalent".into(), |
| help: Some("consider using `u32` or `libc::wchar_t` instead".into()), |
| }, |
| |
| ty::Int(ast::IntTy::I128) | ty::Uint(ast::UintTy::U128) => FfiUnsafe { |
| ty, |
| reason: "128-bit integers don't currently have a known stable ABI".into(), |
| help: None, |
| }, |
| |
| // Primitive types with a stable representation. |
| ty::Bool | ty::Int(..) | ty::Uint(..) | ty::Float(..) | ty::Never => FfiSafe, |
| |
| ty::Slice(_) => FfiUnsafe { |
| ty, |
| reason: "slices have no C equivalent".into(), |
| help: Some("consider using a raw pointer instead".into()), |
| }, |
| |
| ty::Dynamic(..) => { |
| FfiUnsafe { ty, reason: "trait objects have no C equivalent".into(), help: None } |
| } |
| |
| ty::Str => FfiUnsafe { |
| ty, |
| reason: "string slices have no C equivalent".into(), |
| help: Some("consider using `*const u8` and a length instead".into()), |
| }, |
| |
| ty::Tuple(..) => FfiUnsafe { |
| ty, |
| reason: "tuples have unspecified layout".into(), |
| help: Some("consider using a struct instead".into()), |
| }, |
| |
| ty::RawPtr(ty::TypeAndMut { ty, .. }) | ty::Ref(_, ty, _) |
| if { |
| matches!(self.mode, ImproperCTypesMode::Definitions) |
| && ty.is_sized(self.cx.tcx.at(DUMMY_SP), self.cx.param_env) |
| } => |
| { |
| 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: "this function pointer has Rust-specific calling convention".into(), |
| help: Some( |
| "consider using an `extern fn(...) -> ...` \ |
| function pointer instead" |
| .into(), |
| ), |
| }; |
| } |
| |
| let sig = cx.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::Opaque(..) => { |
| FfiUnsafe { ty, reason: "opaque types have no C equivalent".into(), 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::Projection(..) |
| if matches!(self.mode, ImproperCTypesMode::Definitions) => |
| { |
| FfiSafe |
| } |
| |
| ty::Param(..) |
| | ty::Projection(..) |
| | ty::Infer(..) |
| | ty::Bound(..) |
| | ty::Error(_) |
| | ty::Closure(..) |
| | ty::Generator(..) |
| | ty::GeneratorWitness(..) |
| | 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: &str, |
| help: Option<&str>, |
| ) { |
| let lint = match self.mode { |
| ImproperCTypesMode::Declarations => IMPROPER_CTYPES, |
| ImproperCTypesMode::Definitions => IMPROPER_CTYPES_DEFINITIONS, |
| }; |
| |
| self.cx.struct_span_lint(lint, sp, |lint| { |
| let item_description = match self.mode { |
| ImproperCTypesMode::Declarations => "block", |
| ImproperCTypesMode::Definitions => "fn", |
| }; |
| let mut diag = lint.build(&format!( |
| "`extern` {} uses type `{}`, which is not FFI-safe", |
| item_description, ty |
| )); |
| diag.span_label(sp, "not FFI-safe"); |
| if let Some(help) = help { |
| diag.help(help); |
| } |
| diag.note(note); |
| if let ty::Adt(def, _) = ty.kind { |
| if let Some(sp) = self.cx.tcx.hir().span_if_local(def.did) { |
| diag.span_note(sp, "the type is defined here"); |
| } |
| } |
| diag.emit(); |
| }); |
| } |
| |
| fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool { |
| struct ProhibitOpaqueTypes<'a, 'tcx> { |
| cx: &'a LateContext<'tcx>, |
| ty: Option<Ty<'tcx>>, |
| }; |
| |
| impl<'a, 'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueTypes<'a, 'tcx> { |
| fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool { |
| match ty.kind { |
| ty::Opaque(..) => { |
| self.ty = Some(ty); |
| true |
| } |
| // Consider opaque types within projections FFI-safe if they do not normalize |
| // to more opaque types. |
| ty::Projection(..) => { |
| let ty = self.cx.tcx.normalize_erasing_regions(self.cx.param_env, ty); |
| |
| // If `ty` is a opaque type directly then `super_visit_with` won't invoke |
| // this function again. |
| if ty.has_opaque_types() { self.visit_ty(ty) } else { false } |
| } |
| _ => ty.super_visit_with(self), |
| } |
| } |
| } |
| |
| let mut visitor = ProhibitOpaqueTypes { cx: self.cx, ty: None }; |
| ty.visit_with(&mut visitor); |
| if let Some(ty) = visitor.ty { |
| self.emit_ffi_unsafe_type_lint(ty, sp, "opaque types have no C equivalent", 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, "composed only of `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() => return, |
| FfiResult::FfiUnsafe { ty, reason, help } => { |
| self.emit_ffi_unsafe_type_lint(ty, sp, &reason, help.as_deref()); |
| } |
| } |
| } |
| |
| fn check_foreign_fn(&mut self, id: hir::HirId, decl: &hir::FnDecl<'_>) { |
| let def_id = self.cx.tcx.hir().local_def_id(id); |
| let sig = self.cx.tcx.fn_sig(def_id); |
| let sig = self.cx.tcx.erase_late_bound_regions(&sig); |
| |
| for (input_ty, input_hir) in sig.inputs().iter().zip(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::HirId, span: Span) { |
| let def_id = self.cx.tcx.hir().local_def_id(id); |
| let ty = self.cx.tcx.type_of(def_id); |
| self.check_type_for_ffi_and_report_errors(span, ty, true, false); |
| } |
| |
| fn is_internal_abi(&self, abi: Abi) -> bool { |
| if let Abi::Rust | Abi::RustCall | Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi { |
| true |
| } else { |
| false |
| } |
| } |
| } |
| |
| impl<'tcx> LateLintPass<'tcx> for ImproperCTypesDeclarations { |
| fn check_foreign_item(&mut self, cx: &LateContext<'_>, it: &hir::ForeignItem<'_>) { |
| let mut vis = ImproperCTypesVisitor { cx, mode: ImproperCTypesMode::Declarations }; |
| 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.hir_id, decl); |
| } |
| hir::ForeignItemKind::Static(ref ty, _) => { |
| vis.check_foreign_static(it.hir_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, |
| hir_id: hir::HirId, |
| ) { |
| 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: ImproperCTypesMode::Definitions }; |
| if !vis.is_internal_abi(abi) { |
| vis.check_foreign_fn(hir_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 item_def_id = cx.tcx.hir().local_def_id(it.hir_id); |
| let t = cx.tcx.type_of(item_def_id); |
| let ty = cx.tcx.erase_regions(&t); |
| let layout = match cx.layout_of(ty) { |
| Ok(layout) => layout, |
| Err( |
| ty::layout::LayoutError::Unknown(_) | ty::layout::LayoutError::SizeOverflow(_), |
| ) => return, |
| }; |
| let (variants, tag) = match layout.variants { |
| Variants::Multiple { |
| tag_encoding: TagEncoding::Direct, |
| ref tag, |
| ref variants, |
| .. |
| } => (variants, tag), |
| _ => return, |
| }; |
| |
| let tag_size = tag.value.size(&cx.tcx).bytes(); |
| |
| debug!( |
| "enum `{}` is {} bytes large with layout:\n{:#?}", |
| t, |
| layout.size.bytes(), |
| layout |
| ); |
| |
| let (largest, slargest, largest_index) = enum_definition |
| .variants |
| .iter() |
| .zip(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.struct_span_lint( |
| VARIANT_SIZE_DIFFERENCES, |
| enum_definition.variants[largest_index].span, |
| |lint| { |
| lint.build(&format!( |
| "enum variant is more than three times \ |
| larger ({} bytes) than the next largest", |
| largest |
| )) |
| .emit() |
| }, |
| ); |
| } |
| } |
| } |
| } |
