| use rustc_middle::mir::visit::{PlaceContext, Visitor}; |
| use rustc_middle::mir::*; |
| use rustc_middle::ty::{self, TyCtxt}; |
| use rustc_session::lint::builtin::UNALIGNED_REFERENCES; |
| |
| use crate::transform::MirPass; |
| use crate::util; |
| |
| pub struct CheckPackedRef; |
| |
| impl<'tcx> MirPass<'tcx> for CheckPackedRef { |
| fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) { |
| let param_env = tcx.param_env(body.source.def_id()); |
| let source_info = SourceInfo::outermost(body.span); |
| let mut checker = PackedRefChecker { body, tcx, param_env, source_info }; |
| checker.visit_body(&body); |
| } |
| } |
| |
| struct PackedRefChecker<'a, 'tcx> { |
| body: &'a Body<'tcx>, |
| tcx: TyCtxt<'tcx>, |
| param_env: ty::ParamEnv<'tcx>, |
| source_info: SourceInfo, |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for PackedRefChecker<'a, 'tcx> { |
| fn visit_terminator(&mut self, terminator: &Terminator<'tcx>, location: Location) { |
| // Make sure we know where in the MIR we are. |
| self.source_info = terminator.source_info; |
| self.super_terminator(terminator, location); |
| } |
| |
| fn visit_statement(&mut self, statement: &Statement<'tcx>, location: Location) { |
| // Make sure we know where in the MIR we are. |
| self.source_info = statement.source_info; |
| self.super_statement(statement, location); |
| } |
| |
| fn visit_place(&mut self, place: &Place<'tcx>, context: PlaceContext, _location: Location) { |
| if context.is_borrow() { |
| if util::is_disaligned(self.tcx, self.body, self.param_env, *place) { |
| let source_info = self.source_info; |
| let lint_root = self.body.source_scopes[source_info.scope] |
| .local_data |
| .as_ref() |
| .assert_crate_local() |
| .lint_root; |
| self.tcx.struct_span_lint_hir( |
| UNALIGNED_REFERENCES, |
| lint_root, |
| source_info.span, |
| |lint| { |
| lint.build("reference to packed field is unaligned") |
| .note( |
| "fields of packed structs are not properly aligned, and creating \ |
| a misaligned reference is undefined behavior (even if that \ |
| reference is never dereferenced)", |
| ) |
| .emit() |
| }, |
| ); |
| } |
| } |
| } |
| } |