72 lines
2.8 KiB
Rust
72 lines
2.8 KiB
Rust
use rustc_errors::struct_span_err;
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use rustc_middle::mir::visit::{PlaceContext, Visitor};
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use rustc_middle::mir::*;
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use rustc_middle::ty::{self, TyCtxt};
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use crate::util;
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use crate::MirLint;
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pub struct CheckPackedRef;
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impl<'tcx> MirLint<'tcx> for CheckPackedRef {
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fn run_lint(&self, tcx: TyCtxt<'tcx>, body: &Body<'tcx>) {
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let param_env = tcx.param_env(body.source.def_id());
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let source_info = SourceInfo::outermost(body.span);
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let mut checker = PackedRefChecker { body, tcx, param_env, source_info };
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checker.visit_body(&body);
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}
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}
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struct PackedRefChecker<'a, 'tcx> {
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body: &'a Body<'tcx>,
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tcx: TyCtxt<'tcx>,
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param_env: ty::ParamEnv<'tcx>,
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source_info: SourceInfo,
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}
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impl<'tcx> Visitor<'tcx> for PackedRefChecker<'_, 'tcx> {
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fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) {
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// Make sure we know where in the MIR we are.
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self.source_info = terminator.source_info;
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self.super_terminator(terminator, location);
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}
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fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) {
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// Make sure we know where in the MIR we are.
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self.source_info = statement.source_info;
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self.super_statement(statement, location);
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}
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fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) {
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if context.is_borrow() {
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if util::is_disaligned(self.tcx, self.body, self.param_env, *place) {
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let def_id = self.body.source.instance.def_id();
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if let Some(impl_def_id) = self.tcx.impl_of_method(def_id)
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&& self.tcx.is_builtin_derive(impl_def_id)
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{
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// If we ever reach here it means that the generated derive
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// code is somehow doing an unaligned reference, which it
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// shouldn't do.
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unreachable!();
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} else {
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struct_span_err!(
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self.tcx.sess,
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self.source_info.span,
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E0793,
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"reference to packed field is unaligned"
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)
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.note(
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"fields of packed structs are not properly aligned, and creating \
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a misaligned reference is undefined behavior (even if that \
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reference is never dereferenced)",
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).help(
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"copy the field contents to a local variable, or replace the \
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reference with a raw pointer and use `read_unaligned`/`write_unaligned` \
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(loads and stores via `*p` must be properly aligned even when using raw pointers)"
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)
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.emit();
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}
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}
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}
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}
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}
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