1079 lines
40 KiB
Rust
1079 lines
40 KiB
Rust
#![allow(non_snake_case)]
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use crate::hir::def_id::DefId;
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use lint::{LateContext, LintArray, LintContext};
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use lint::{LateLintPass, LintPass};
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use rustc::lint;
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use rustc::mir::interpret::{sign_extend, truncate};
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use rustc::ty::layout::{self, IntegerExt, LayoutOf, SizeSkeleton, VariantIdx};
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use rustc::ty::subst::SubstsRef;
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use rustc::ty::{self, AdtKind, ParamEnv, Ty, TyCtxt};
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use rustc_data_structures::fx::FxHashSet;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_hir::{is_range_literal, ExprKind, Node};
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use rustc_index::vec::Idx;
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use rustc_span::source_map;
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use rustc_span::symbol::sym;
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use rustc_span::Span;
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use rustc_target::spec::abi::Abi;
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use syntax::{ast, attr};
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use log::debug;
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use std::cmp;
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use std::{f32, f64, i16, i32, i64, i8, u16, u32, u64, u8};
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declare_lint! {
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UNUSED_COMPARISONS,
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Warn,
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"comparisons made useless by limits of the types involved"
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}
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declare_lint! {
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OVERFLOWING_LITERALS,
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Deny,
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"literal out of range for its type"
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}
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declare_lint! {
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VARIANT_SIZE_DIFFERENCES,
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Allow,
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"detects enums with widely varying variant sizes"
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}
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#[derive(Copy, Clone)]
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pub struct TypeLimits {
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/// Id of the last visited negated expression
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negated_expr_id: hir::HirId,
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}
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impl_lint_pass!(TypeLimits => [UNUSED_COMPARISONS, OVERFLOWING_LITERALS]);
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impl TypeLimits {
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pub fn new() -> TypeLimits {
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TypeLimits { negated_expr_id: hir::DUMMY_HIR_ID }
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}
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}
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/// Attempts to special-case the overflowing literal lint when it occurs as a range endpoint.
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/// Returns `true` iff the lint was overridden.
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fn lint_overflowing_range_endpoint<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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lit: &hir::Lit,
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lit_val: u128,
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max: u128,
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expr: &'tcx hir::Expr<'tcx>,
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parent_expr: &'tcx hir::Expr<'tcx>,
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ty: &str,
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) -> bool {
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// We only want to handle exclusive (`..`) ranges,
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// which are represented as `ExprKind::Struct`.
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if let ExprKind::Struct(_, eps, _) = &parent_expr.kind {
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if eps.len() != 2 {
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return false;
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}
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// We can suggest using an inclusive range
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// (`..=`) instead only if it is the `end` that is
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// overflowing and only by 1.
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if eps[1].expr.hir_id == expr.hir_id && lit_val - 1 == max {
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let mut err = cx.struct_span_lint(
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OVERFLOWING_LITERALS,
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parent_expr.span,
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&format!("range endpoint is out of range for `{}`", ty),
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);
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if let Ok(start) = cx.sess().source_map().span_to_snippet(eps[0].span) {
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use ast::{LitIntType, LitKind};
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// We need to preserve the literal's suffix,
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// as it may determine typing information.
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let suffix = match lit.node {
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LitKind::Int(_, LitIntType::Signed(s)) => format!("{}", s.name_str()),
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LitKind::Int(_, LitIntType::Unsigned(s)) => format!("{}", s.name_str()),
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LitKind::Int(_, LitIntType::Unsuffixed) => "".to_owned(),
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_ => bug!(),
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};
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let suggestion = format!("{}..={}{}", start, lit_val - 1, suffix);
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err.span_suggestion(
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parent_expr.span,
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&"use an inclusive range instead",
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suggestion,
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Applicability::MachineApplicable,
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);
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err.emit();
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return true;
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}
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}
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}
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false
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}
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// For `isize` & `usize`, be conservative with the warnings, so that the
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// warnings are consistent between 32- and 64-bit platforms.
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fn int_ty_range(int_ty: ast::IntTy) -> (i128, i128) {
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match int_ty {
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ast::IntTy::Isize => (i64::min_value() as i128, i64::max_value() as i128),
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ast::IntTy::I8 => (i8::min_value() as i64 as i128, i8::max_value() as i128),
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ast::IntTy::I16 => (i16::min_value() as i64 as i128, i16::max_value() as i128),
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ast::IntTy::I32 => (i32::min_value() as i64 as i128, i32::max_value() as i128),
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ast::IntTy::I64 => (i64::min_value() as i128, i64::max_value() as i128),
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ast::IntTy::I128 => (i128::min_value() as i128, i128::max_value()),
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}
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}
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fn uint_ty_range(uint_ty: ast::UintTy) -> (u128, u128) {
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match uint_ty {
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ast::UintTy::Usize => (u64::min_value() as u128, u64::max_value() as u128),
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ast::UintTy::U8 => (u8::min_value() as u128, u8::max_value() as u128),
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ast::UintTy::U16 => (u16::min_value() as u128, u16::max_value() as u128),
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ast::UintTy::U32 => (u32::min_value() as u128, u32::max_value() as u128),
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ast::UintTy::U64 => (u64::min_value() as u128, u64::max_value() as u128),
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ast::UintTy::U128 => (u128::min_value(), u128::max_value()),
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}
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}
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fn get_bin_hex_repr(cx: &LateContext<'_, '_>, lit: &hir::Lit) -> Option<String> {
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let src = cx.sess().source_map().span_to_snippet(lit.span).ok()?;
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let firstch = src.chars().next()?;
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if firstch == '0' {
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match src.chars().nth(1) {
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Some('x') | Some('b') => return Some(src),
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_ => return None,
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}
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}
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None
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}
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fn report_bin_hex_error(
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cx: &LateContext<'_, '_>,
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expr: &hir::Expr<'_>,
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ty: attr::IntType,
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repr_str: String,
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val: u128,
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negative: bool,
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) {
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let size = layout::Integer::from_attr(&cx.tcx, ty).size();
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let (t, actually) = match ty {
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attr::IntType::SignedInt(t) => {
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let actually = sign_extend(val, size) as i128;
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(t.name_str(), actually.to_string())
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}
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attr::IntType::UnsignedInt(t) => {
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let actually = truncate(val, size);
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(t.name_str(), actually.to_string())
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}
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};
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let mut err = cx.struct_span_lint(
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OVERFLOWING_LITERALS,
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expr.span,
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&format!("literal out of range for {}", t),
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);
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err.note(&format!(
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"the literal `{}` (decimal `{}`) does not fit into \
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an `{}` and will become `{}{}`",
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repr_str, val, t, actually, t
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));
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if let Some(sugg_ty) = get_type_suggestion(&cx.tables.node_type(expr.hir_id), val, negative) {
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if let Some(pos) = repr_str.chars().position(|c| c == 'i' || c == 'u') {
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let (sans_suffix, _) = repr_str.split_at(pos);
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err.span_suggestion(
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expr.span,
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&format!("consider using `{}` instead", sugg_ty),
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format!("{}{}", sans_suffix, sugg_ty),
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Applicability::MachineApplicable,
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);
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} else {
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err.help(&format!("consider using `{}` instead", sugg_ty));
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}
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}
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err.emit();
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}
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// This function finds the next fitting type and generates a suggestion string.
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// It searches for fitting types in the following way (`X < Y`):
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// - `iX`: if literal fits in `uX` => `uX`, else => `iY`
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// - `-iX` => `iY`
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// - `uX` => `uY`
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//
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// No suggestion for: `isize`, `usize`.
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fn get_type_suggestion(t: Ty<'_>, val: u128, negative: bool) -> Option<&'static str> {
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use syntax::ast::IntTy::*;
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use syntax::ast::UintTy::*;
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macro_rules! find_fit {
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($ty:expr, $val:expr, $negative:expr,
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$($type:ident => [$($utypes:expr),*] => [$($itypes:expr),*]),+) => {
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{
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let _neg = if negative { 1 } else { 0 };
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match $ty {
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$($type => {
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$(if !negative && val <= uint_ty_range($utypes).1 {
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return Some($utypes.name_str())
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})*
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$(if val <= int_ty_range($itypes).1 as u128 + _neg {
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return Some($itypes.name_str())
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})*
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None
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},)+
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_ => None
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}
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}
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}
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}
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match t.kind {
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ty::Int(i) => find_fit!(i, val, negative,
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I8 => [U8] => [I16, I32, I64, I128],
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I16 => [U16] => [I32, I64, I128],
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I32 => [U32] => [I64, I128],
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I64 => [U64] => [I128],
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I128 => [U128] => []),
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ty::Uint(u) => find_fit!(u, val, negative,
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U8 => [U8, U16, U32, U64, U128] => [],
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U16 => [U16, U32, U64, U128] => [],
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U32 => [U32, U64, U128] => [],
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U64 => [U64, U128] => [],
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U128 => [U128] => []),
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_ => None,
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}
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}
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fn lint_int_literal<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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type_limits: &TypeLimits,
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e: &'tcx hir::Expr<'tcx>,
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lit: &hir::Lit,
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t: ast::IntTy,
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v: u128,
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) {
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let int_type = t.normalize(cx.sess().target.ptr_width);
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let (_, max) = int_ty_range(int_type);
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let max = max as u128;
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let negative = type_limits.negated_expr_id == e.hir_id;
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// Detect literal value out of range [min, max] inclusive
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// avoiding use of -min to prevent overflow/panic
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if (negative && v > max + 1) || (!negative && v > max) {
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if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
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report_bin_hex_error(cx, e, attr::IntType::SignedInt(t), repr_str, v, negative);
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return;
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}
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let par_id = cx.tcx.hir().get_parent_node(e.hir_id);
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if let Node::Expr(par_e) = cx.tcx.hir().get(par_id) {
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if let hir::ExprKind::Struct(..) = par_e.kind {
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if is_range_literal(cx.sess().source_map(), par_e)
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&& lint_overflowing_range_endpoint(cx, lit, v, max, e, par_e, t.name_str())
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{
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// The overflowing literal lint was overridden.
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return;
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}
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}
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}
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cx.span_lint(
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OVERFLOWING_LITERALS,
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e.span,
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&format!("literal out of range for `{}`", t.name_str()),
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);
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}
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}
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fn lint_uint_literal<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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e: &'tcx hir::Expr<'tcx>,
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lit: &hir::Lit,
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t: ast::UintTy,
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) {
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let uint_type = t.normalize(cx.sess().target.ptr_width);
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let (min, max) = uint_ty_range(uint_type);
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let lit_val: u128 = match lit.node {
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// _v is u8, within range by definition
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ast::LitKind::Byte(_v) => return,
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ast::LitKind::Int(v, _) => v,
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_ => bug!(),
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};
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if lit_val < min || lit_val > max {
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let parent_id = cx.tcx.hir().get_parent_node(e.hir_id);
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if let Node::Expr(par_e) = cx.tcx.hir().get(parent_id) {
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match par_e.kind {
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hir::ExprKind::Cast(..) => {
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if let ty::Char = cx.tables.expr_ty(par_e).kind {
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let mut err = cx.struct_span_lint(
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OVERFLOWING_LITERALS,
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par_e.span,
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"only `u8` can be cast into `char`",
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);
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err.span_suggestion(
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par_e.span,
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&"use a `char` literal instead",
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format!("'\\u{{{:X}}}'", lit_val),
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Applicability::MachineApplicable,
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);
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err.emit();
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return;
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}
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}
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hir::ExprKind::Struct(..) if is_range_literal(cx.sess().source_map(), par_e) => {
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let t = t.name_str();
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if lint_overflowing_range_endpoint(cx, lit, lit_val, max, e, par_e, t) {
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// The overflowing literal lint was overridden.
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return;
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}
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}
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_ => {}
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}
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}
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if let Some(repr_str) = get_bin_hex_repr(cx, lit) {
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report_bin_hex_error(cx, e, attr::IntType::UnsignedInt(t), repr_str, lit_val, false);
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return;
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}
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cx.span_lint(
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OVERFLOWING_LITERALS,
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e.span,
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&format!("literal out of range for `{}`", t.name_str()),
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);
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}
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}
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fn lint_literal<'a, 'tcx>(
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cx: &LateContext<'a, 'tcx>,
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type_limits: &TypeLimits,
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e: &'tcx hir::Expr<'tcx>,
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lit: &hir::Lit,
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) {
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match cx.tables.node_type(e.hir_id).kind {
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ty::Int(t) => {
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match lit.node {
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ast::LitKind::Int(v, ast::LitIntType::Signed(_))
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| ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => {
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lint_int_literal(cx, type_limits, e, lit, t, v)
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}
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_ => bug!(),
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};
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}
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ty::Uint(t) => lint_uint_literal(cx, e, lit, t),
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ty::Float(t) => {
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let is_infinite = match lit.node {
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ast::LitKind::Float(v, _) => match t {
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ast::FloatTy::F32 => v.as_str().parse().map(f32::is_infinite),
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ast::FloatTy::F64 => v.as_str().parse().map(f64::is_infinite),
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},
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_ => bug!(),
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};
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if is_infinite == Ok(true) {
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cx.span_lint(
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OVERFLOWING_LITERALS,
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e.span,
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&format!("literal out of range for `{}`", t.name_str()),
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);
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}
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}
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_ => {}
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}
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}
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|
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeLimits {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx hir::Expr<'tcx>) {
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match e.kind {
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hir::ExprKind::Unary(hir::UnOp::UnNeg, ref expr) => {
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// propagate negation, if the negation itself isn't negated
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if self.negated_expr_id != e.hir_id {
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self.negated_expr_id = expr.hir_id;
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}
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}
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hir::ExprKind::Binary(binop, ref l, ref r) => {
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if is_comparison(binop) && !check_limits(cx, binop, &l, &r) {
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cx.span_lint(
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UNUSED_COMPARISONS,
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e.span,
|
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"comparison is useless due to type limits",
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);
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}
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}
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hir::ExprKind::Lit(ref lit) => lint_literal(cx, self, e, lit),
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_ => {}
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};
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|
|
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fn is_valid<T: cmp::PartialOrd>(binop: hir::BinOp, v: T, min: T, max: T) -> bool {
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match binop.node {
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hir::BinOpKind::Lt => v > min && v <= max,
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hir::BinOpKind::Le => v >= min && v < max,
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hir::BinOpKind::Gt => v >= min && v < max,
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hir::BinOpKind::Ge => v > min && v <= max,
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hir::BinOpKind::Eq | hir::BinOpKind::Ne => v >= min && v <= max,
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_ => bug!(),
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}
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|
}
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|
|
|
fn rev_binop(binop: hir::BinOp) -> hir::BinOp {
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source_map::respan(
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binop.span,
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|
match binop.node {
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hir::BinOpKind::Lt => hir::BinOpKind::Gt,
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hir::BinOpKind::Le => hir::BinOpKind::Ge,
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hir::BinOpKind::Gt => hir::BinOpKind::Lt,
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hir::BinOpKind::Ge => hir::BinOpKind::Le,
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_ => return binop,
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},
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)
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}
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|
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fn check_limits(
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cx: &LateContext<'_, '_>,
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binop: hir::BinOp,
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l: &hir::Expr<'_>,
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r: &hir::Expr<'_>,
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) -> bool {
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let (lit, expr, swap) = match (&l.kind, &r.kind) {
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(&hir::ExprKind::Lit(_), _) => (l, r, true),
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(_, &hir::ExprKind::Lit(_)) => (r, l, false),
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_ => return true,
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};
|
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// Normalize the binop so that the literal is always on the RHS in
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// the comparison
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let norm_binop = if swap { rev_binop(binop) } else { binop };
|
|
match cx.tables.node_type(expr.hir_id).kind {
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|
ty::Int(int_ty) => {
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let (min, max) = int_ty_range(int_ty);
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let lit_val: i128 = match lit.kind {
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hir::ExprKind::Lit(ref li) => match li.node {
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ast::LitKind::Int(v, ast::LitIntType::Signed(_))
|
|
| ast::LitKind::Int(v, ast::LitIntType::Unsuffixed) => v as i128,
|
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_ => return true,
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},
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_ => bug!(),
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};
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is_valid(norm_binop, lit_val, min, max)
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}
|
|
ty::Uint(uint_ty) => {
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let (min, max): (u128, u128) = uint_ty_range(uint_ty);
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|
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!(ImproperCTypes => [IMPROPER_CTYPES]);
|
|
|
|
struct ImproperCTypesVisitor<'a, 'tcx> {
|
|
cx: &'a LateContext<'a, 'tcx>,
|
|
}
|
|
|
|
enum FfiResult<'tcx> {
|
|
FfiSafe,
|
|
FfiPhantom(Ty<'tcx>),
|
|
FfiUnsafe { ty: Ty<'tcx>, reason: &'static str, help: Option<&'static str> },
|
|
}
|
|
|
|
fn is_zst<'tcx>(tcx: TyCtxt<'tcx>, did: DefId, ty: Ty<'tcx>) -> bool {
|
|
tcx.layout_of(tcx.param_env(did).and(ty)).map(|layout| layout.is_zst()).unwrap_or(false)
|
|
}
|
|
|
|
fn ty_is_known_nonnull<'tcx>(tcx: TyCtxt<'tcx>, 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 =
|
|
tcx.normalize_erasing_regions(ParamEnv::reveal_all(), field.ty(tcx, substs));
|
|
if is_zst(tcx, field.did, field_ty) {
|
|
continue;
|
|
}
|
|
|
|
let attrs = tcx.get_attrs(field_def.did);
|
|
if attrs.iter().any(|a| a.check_name(sym::rustc_nonnull_optimization_guaranteed))
|
|
|| ty_is_known_nonnull(tcx, 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.
|
|
/// FIXME: This duplicates code in codegen.
|
|
fn is_repr_nullable_ptr<'tcx>(
|
|
tcx: TyCtxt<'tcx>,
|
|
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(tcx, substs);
|
|
if !ty_is_known_nonnull(tcx, 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 nonnull optimization isn't
|
|
// being applied (and we've got a problem somewhere).
|
|
let compute_size_skeleton = |t| SizeSkeleton::compute(t, tcx, ParamEnv::reveal_all()).unwrap();
|
|
if !compute_size_skeleton(ty).same_size(compute_size_skeleton(field_ty)) {
|
|
bug!("improper_ctypes: Option nonnull optimization not applied?");
|
|
}
|
|
|
|
true
|
|
}
|
|
|
|
impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
|
|
/// Check if the type is array and emit an unsafe type lint.
|
|
fn check_for_array_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
|
|
if let ty::Array(..) = ty.kind {
|
|
self.emit_ffi_unsafe_type_lint(
|
|
ty,
|
|
sp,
|
|
"passing raw arrays by value is not FFI-safe",
|
|
Some("consider passing a pointer to the array"),
|
|
);
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
/// 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 => {
|
|
if !def.repr.c() && !def.repr.transparent() {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this struct has unspecified layout",
|
|
help: Some(
|
|
"consider adding a `#[repr(C)]` or \
|
|
`#[repr(transparent)]` attribute to this struct",
|
|
),
|
|
};
|
|
}
|
|
|
|
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: "this struct is non-exhaustive",
|
|
help: None,
|
|
};
|
|
}
|
|
|
|
if def.non_enum_variant().fields.is_empty() {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this struct has no fields",
|
|
help: Some("consider adding a member to this struct"),
|
|
};
|
|
}
|
|
|
|
// We can't completely trust repr(C) and repr(transparent) markings;
|
|
// make sure the fields are actually safe.
|
|
let mut all_phantom = true;
|
|
for field in &def.non_enum_variant().fields {
|
|
let field_ty = cx.normalize_erasing_regions(
|
|
ParamEnv::reveal_all(),
|
|
field.ty(cx, substs),
|
|
);
|
|
// repr(transparent) types are allowed to have arbitrary ZSTs, not just
|
|
// PhantomData -- skip checking all ZST fields
|
|
if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
|
|
continue;
|
|
}
|
|
let r = self.check_type_for_ffi(cache, field_ty);
|
|
match r {
|
|
FfiSafe => {
|
|
all_phantom = false;
|
|
}
|
|
FfiPhantom(..) => {}
|
|
FfiUnsafe { .. } => {
|
|
return r;
|
|
}
|
|
}
|
|
}
|
|
|
|
if all_phantom { FfiPhantom(ty) } else { FfiSafe }
|
|
}
|
|
AdtKind::Union => {
|
|
if !def.repr.c() && !def.repr.transparent() {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this union has unspecified layout",
|
|
help: Some(
|
|
"consider adding a `#[repr(C)]` or \
|
|
`#[repr(transparent)]` attribute to this union",
|
|
),
|
|
};
|
|
}
|
|
|
|
if def.non_enum_variant().fields.is_empty() {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this union has no fields",
|
|
help: Some("consider adding a field to this union"),
|
|
};
|
|
}
|
|
|
|
let mut all_phantom = true;
|
|
for field in &def.non_enum_variant().fields {
|
|
let field_ty = cx.normalize_erasing_regions(
|
|
ParamEnv::reveal_all(),
|
|
field.ty(cx, substs),
|
|
);
|
|
// repr(transparent) types are allowed to have arbitrary ZSTs, not just
|
|
// PhantomData -- skip checking all ZST fields.
|
|
if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
|
|
continue;
|
|
}
|
|
let r = self.check_type_for_ffi(cache, field_ty);
|
|
match r {
|
|
FfiSafe => {
|
|
all_phantom = false;
|
|
}
|
|
FfiPhantom(..) => {}
|
|
FfiUnsafe { .. } => {
|
|
return r;
|
|
}
|
|
}
|
|
}
|
|
|
|
if all_phantom { FfiPhantom(ty) } else { FfiSafe }
|
|
}
|
|
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 !is_repr_nullable_ptr(cx, ty, def, substs) {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "enum has no representation hint",
|
|
help: Some(
|
|
"consider adding a `#[repr(C)]`, \
|
|
`#[repr(transparent)]`, or integer `#[repr(...)]` \
|
|
attribute to this enum",
|
|
),
|
|
};
|
|
}
|
|
}
|
|
|
|
if def.is_variant_list_non_exhaustive() && !def.did.is_local() {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this enum is non-exhaustive",
|
|
help: None,
|
|
};
|
|
}
|
|
|
|
// Check the contained variants.
|
|
for variant in &def.variants {
|
|
let is_non_exhaustive = variant.is_field_list_non_exhaustive();
|
|
if is_non_exhaustive && !variant.def_id.is_local() {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this enum has non-exhaustive variants",
|
|
help: None,
|
|
};
|
|
}
|
|
|
|
for field in &variant.fields {
|
|
let field_ty = cx.normalize_erasing_regions(
|
|
ParamEnv::reveal_all(),
|
|
field.ty(cx, substs),
|
|
);
|
|
// repr(transparent) types are allowed to have arbitrary ZSTs, not
|
|
// just PhantomData -- skip checking all ZST fields.
|
|
if def.repr.transparent() && is_zst(cx, field.did, field_ty) {
|
|
continue;
|
|
}
|
|
let r = self.check_type_for_ffi(cache, field_ty);
|
|
match r {
|
|
FfiSafe => {}
|
|
FfiUnsafe { .. } => {
|
|
return r;
|
|
}
|
|
FfiPhantom(..) => {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this enum contains a PhantomData field",
|
|
help: None,
|
|
};
|
|
}
|
|
}
|
|
}
|
|
}
|
|
FfiSafe
|
|
}
|
|
}
|
|
}
|
|
|
|
ty::Char => FfiUnsafe {
|
|
ty,
|
|
reason: "the `char` type has no C equivalent",
|
|
help: Some("consider using `u32` or `libc::wchar_t` instead"),
|
|
},
|
|
|
|
ty::Int(ast::IntTy::I128) | ty::Uint(ast::UintTy::U128) => FfiUnsafe {
|
|
ty,
|
|
reason: "128-bit integers don't currently have a known stable ABI",
|
|
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",
|
|
help: Some("consider using a raw pointer instead"),
|
|
},
|
|
|
|
ty::Dynamic(..) => {
|
|
FfiUnsafe { ty, reason: "trait objects have no C equivalent", help: None }
|
|
}
|
|
|
|
ty::Str => FfiUnsafe {
|
|
ty,
|
|
reason: "string slices have no C equivalent",
|
|
help: Some("consider using `*const u8` and a length instead"),
|
|
},
|
|
|
|
ty::Tuple(..) => FfiUnsafe {
|
|
ty,
|
|
reason: "tuples have unspecified layout",
|
|
help: Some("consider using a struct instead"),
|
|
},
|
|
|
|
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) => {
|
|
match sig.abi() {
|
|
Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic | Abi::RustCall => {
|
|
return FfiUnsafe {
|
|
ty,
|
|
reason: "this function pointer has Rust-specific calling convention",
|
|
help: Some(
|
|
"consider using an `extern fn(...) -> ...` \
|
|
function pointer instead",
|
|
),
|
|
};
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
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,
|
|
|
|
ty::Param(..)
|
|
| ty::Infer(..)
|
|
| ty::Bound(..)
|
|
| ty::Error
|
|
| ty::Closure(..)
|
|
| ty::Generator(..)
|
|
| ty::GeneratorWitness(..)
|
|
| ty::Placeholder(..)
|
|
| ty::UnnormalizedProjection(..)
|
|
| ty::Projection(..)
|
|
| ty::Opaque(..)
|
|
| 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 mut diag = self.cx.struct_span_lint(
|
|
IMPROPER_CTYPES,
|
|
sp,
|
|
&format!("`extern` block uses type `{}`, which is not FFI-safe", 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, "type defined here");
|
|
}
|
|
}
|
|
diag.emit();
|
|
}
|
|
|
|
fn check_for_opaque_ty(&mut self, sp: Span, ty: Ty<'tcx>) -> bool {
|
|
use crate::rustc::ty::TypeFoldable;
|
|
|
|
struct ProhibitOpaqueTypes<'tcx> {
|
|
ty: Option<Ty<'tcx>>,
|
|
};
|
|
|
|
impl<'tcx> ty::fold::TypeVisitor<'tcx> for ProhibitOpaqueTypes<'tcx> {
|
|
fn visit_ty(&mut self, ty: Ty<'tcx>) -> bool {
|
|
if let ty::Opaque(..) = ty.kind {
|
|
self.ty = Some(ty);
|
|
true
|
|
} else {
|
|
ty.super_visit_with(self)
|
|
}
|
|
}
|
|
}
|
|
|
|
let mut visitor = ProhibitOpaqueTypes { 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) {
|
|
// 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(ParamEnv::reveal_all(), ty);
|
|
// C doesn't really support passing arrays by value.
|
|
// The only way to pass an array by value is through a struct.
|
|
// So we 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;
|
|
}
|
|
|
|
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);
|
|
}
|
|
FfiResult::FfiUnsafe { ty, reason, help } => {
|
|
self.emit_ffi_unsafe_type_lint(ty, sp, reason, help);
|
|
}
|
|
}
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
if let hir::FunctionRetTy::Return(ref ret_hir) = decl.output {
|
|
let ret_ty = sig.output();
|
|
if !ret_ty.is_unit() {
|
|
self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty, false);
|
|
}
|
|
}
|
|
}
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImproperCTypes {
|
|
fn check_foreign_item(&mut self, cx: &LateContext<'_, '_>, it: &hir::ForeignItem<'_>) {
|
|
let mut vis = ImproperCTypesVisitor { cx };
|
|
let abi = cx.tcx.hir().get_foreign_abi(it.hir_id);
|
|
if let Abi::Rust | Abi::RustCall | Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
|
|
// Don't worry about types in internal ABIs.
|
|
} else {
|
|
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 => (),
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
declare_lint_pass!(VariantSizeDifferences => [VARIANT_SIZE_DIFFERENCES]);
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, '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(_)) => return,
|
|
Err(err @ ty::layout::LayoutError::SizeOverflow(_)) => {
|
|
bug!("failed to get layout for `{}`: {}", t, err);
|
|
}
|
|
};
|
|
let (variants, tag) = match layout.variants {
|
|
layout::Variants::Multiple {
|
|
discr_kind: layout::DiscriminantKind::Tag,
|
|
ref discr,
|
|
ref variants,
|
|
..
|
|
} => (variants, discr),
|
|
_ => return,
|
|
};
|
|
|
|
let discr_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 discriminant.
|
|
let bytes = variant_layout.size.bytes().saturating_sub(discr_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.span_lint(
|
|
VARIANT_SIZE_DIFFERENCES,
|
|
enum_definition.variants[largest_index].span,
|
|
&format!(
|
|
"enum variant is more than three times \
|
|
larger ({} bytes) than the next largest",
|
|
largest
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|