116 lines
4.5 KiB
Rust
116 lines
4.5 KiB
Rust
use rustc_hir::def_id::{DefId, LocalDefId};
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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::query::Providers;
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use rustc_middle::ty::{self, TyCtxt};
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use rustc_session::lint::builtin::UNALIGNED_REFERENCES;
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use rustc_span::symbol::sym;
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use crate::util;
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use crate::MirPass;
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pub(crate) fn provide(providers: &mut Providers) {
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*providers = Providers { unsafe_derive_on_repr_packed, ..*providers };
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}
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pub struct CheckPackedRef;
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impl<'tcx> MirPass<'tcx> for CheckPackedRef {
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fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut 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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fn unsafe_derive_on_repr_packed(tcx: TyCtxt<'_>, def_id: LocalDefId) {
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let lint_hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
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tcx.struct_span_lint_hir(UNALIGNED_REFERENCES, lint_hir_id, tcx.def_span(def_id), |lint| {
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// FIXME: when we make this a hard error, this should have its
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// own error code.
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let message = if tcx.generics_of(def_id).own_requires_monomorphization() {
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"`#[derive]` can't be used on a `#[repr(packed)]` struct with \
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type or const parameters (error E0133)"
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.to_string()
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} else {
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"`#[derive]` can't be used on a `#[repr(packed)]` struct that \
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does not derive Copy (error E0133)"
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.to_string()
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};
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lint.build(&message).emit()
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});
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}
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fn builtin_derive_def_id(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
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debug!("builtin_derive_def_id({:?})", def_id);
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if let Some(impl_def_id) = tcx.impl_of_method(def_id) {
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if tcx.has_attr(impl_def_id, sym::automatically_derived) {
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debug!("builtin_derive_def_id({:?}) - is {:?}", def_id, impl_def_id);
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Some(impl_def_id)
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} else {
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debug!("builtin_derive_def_id({:?}) - not automatically derived", def_id);
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None
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}
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} else {
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debug!("builtin_derive_def_id({:?}) - not a method", def_id);
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None
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}
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}
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impl<'a, 'tcx> Visitor<'tcx> for PackedRefChecker<'a, '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) = builtin_derive_def_id(self.tcx, def_id) {
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// If a method is defined in the local crate,
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// the impl containing that method should also be.
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self.tcx.ensure().unsafe_derive_on_repr_packed(impl_def_id.expect_local());
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} else {
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let source_info = self.source_info;
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let lint_root = self.body.source_scopes[source_info.scope]
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.local_data
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.as_ref()
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.assert_crate_local()
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.lint_root;
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self.tcx.struct_span_lint_hir(
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UNALIGNED_REFERENCES,
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lint_root,
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source_info.span,
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|lint| {
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lint.build("reference to packed field is unaligned")
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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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)
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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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}
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}
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