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