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Resolver: (un)tracked borrows for CmRefCell made safe by unsafe speculative flag #160510

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Merged
rust-bors merged 1 commit into from
Aug 5, 2026
Merged

Resolver: (un)tracked borrows for CmRefCell made safe by unsafe speculative flag #160510

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2 changes: 1 addition & 1 deletion compiler/rustc_resolve/src/check_unused.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -559,7 +559,7 @@ impl Resolver<'_, '_> {
let mut check_redundant_imports = FxIndexSet::default();
for module in &self.local_modules {
for (_key, resolution) in self.resolutions(module.to_module()).iter() {
if let Some(decl) = resolution.borrow().best_decl()
if let Some(decl) = resolution.borrow(self).best_decl()
&& let DeclKind::Import { import, .. } = decl.kind
&& let ImportKind::Single { id, .. } = import.kind
{
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_resolve/src/diagnostics/impls.rs
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Expand Up @@ -1873,7 +1873,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
self.resolutions(parent_scope.module).iter().any(|(key, name_resolution)| {
if key.ns == TypeNS
&& key.ident == *ident
&& let Some(decl) = name_resolution.borrow().best_decl()
&& let Some(decl) = name_resolution.borrow(self).best_decl()
{
match decl.res() {
// No disambiguation needed if the identically named item we
Expand Down Expand Up @@ -3603,7 +3603,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
let mut res = false;
let m = r.expect_module(parent_module);
if m.is_local() {
for importer in m.glob_importers.borrow().iter() {
for importer in m.glob_importers.borrow(r).iter() {
if let Some(next_parent_module) = importer.parent_scope.module.opt_def_id()
{
if next_parent_module == module
Expand Down
4 changes: 2 additions & 2 deletions compiler/rustc_resolve/src/effective_visibilities.rs
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Expand Up @@ -126,7 +126,7 @@ impl<'a, 'ra, 'tcx> EffectiveVisibilitiesVisitor<'a, 'ra, 'tcx> {
fn set_bindings_effective_visibilities(&mut self, module_id: LocalDefId) {
let module = self.r.expect_module(module_id.to_def_id());
for (_, name_resolution) in self.r.resolutions(module).iter() {
let Some(decl) = name_resolution.borrow().best_decl() else {
let Some(decl) = name_resolution.borrow(self.r).best_decl() else {
continue;
};
self.update_decl_chain(decl, ParentId::Def(module_id));
Expand Down Expand Up @@ -310,7 +310,7 @@ impl<'a, 'ra, 'tcx> EffectiveVisibilitiesVisitor<'a, 'ra, 'tcx> {
if self.macro_reachable.insert((module_def_id, defining_mod)) {
let module = self.r.expect_module(module_def_id.to_def_id());
for (_, name_resolution) in self.r.resolutions(module).iter() {
let Some(decl) = name_resolution.borrow().best_decl() else {
let Some(decl) = name_resolution.borrow(self.r).best_decl() else {
continue;
};

Expand Down
25 changes: 15 additions & 10 deletions compiler/rustc_resolve/src/ident.rs
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Expand Up @@ -714,7 +714,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
}
Scope::MacroUsePrelude => match self.macro_use_prelude.get(&ident.name).cloned() {
Some(decl) => Ok(decl),
None => Err(Determinacy::determined(!self.graph_root.has_unexpanded_invocations())),
None => {
Err(Determinacy::determined(!self.graph_root.has_unexpanded_invocations(&self)))
}
},
Scope::BuiltinAttrs => match self.builtin_attr_decls.get(&ident.name) {
Some(decl) => Ok(*decl),
Expand All @@ -727,9 +729,9 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
finalize.is_some(),
) {
Some(decl) => Ok(decl),
None => {
Err(Determinacy::determined(!self.graph_root.has_unexpanded_invocations()))
}
None => Err(Determinacy::determined(
!self.graph_root.has_unexpanded_invocations(&self),
)),
}
}
Scope::ExternPreludeFlags => {
Expand Down Expand Up @@ -1158,7 +1160,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {

if let Some(finalize) = finalize {
// finalize implies that the module is fully expanded
assert!(!module.has_unexpanded_invocations());
assert!(!module.has_unexpanded_invocations(&self));
return self.get_mut().finalize_module_binding(
ident,
orig_ident_span,
Expand Down Expand Up @@ -1195,7 +1197,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
}

// Check if one of unexpanded macros can still define the name.
if module.has_unexpanded_invocations() {
if module.has_unexpanded_invocations(&self) {
return Err(ControlFlow::Continue(Undetermined));
}

Expand Down Expand Up @@ -1224,7 +1226,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {

if let Some(finalize) = finalize {
// finalize implies that the module is fully expanded
assert!(!module.has_unexpanded_invocations());
assert!(!module.has_unexpanded_invocations(&self));
return self.get_mut().finalize_module_binding(
ident,
orig_ident_span,
Expand Down Expand Up @@ -1268,7 +1270,10 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
// and prohibit access to macro-expanded `macro_export` macros instead (unless restricted
// shadowing is enabled, see `macro_expanded_macro_export_errors`).
if let Some(binding) = binding {
return if binding.determined() || ns == MacroNS || shadowing == Shadowing::Restricted {
return if binding.determined(&self)
|| ns == MacroNS
|| shadowing == Shadowing::Restricted
{
let accessible = self.is_accessible_from(binding.vis(), parent_scope.module);
if accessible { Ok(binding) } else { Err(ControlFlow::Break(Determined)) }
} else {
Expand All @@ -1283,13 +1288,13 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
// scopes we return `Undetermined` with `ControlFlow::Continue`.
// Check if one of unexpanded macros can still define the name,
// if it can then our "no resolution" result is not determined and can be invalidated.
if module.has_unexpanded_invocations() {
if module.has_unexpanded_invocations(&self) {
return Err(ControlFlow::Continue(Undetermined));
}

// Check if one of glob imports can still define the name,
// if it can then our "no resolution" result is not determined and can be invalidated.
for glob_import in module.globs.borrow().iter() {
for glob_import in module.globs.borrow(&self).iter() {
if ignore_import == Some(*glob_import) {
continue;
}
Expand Down
18 changes: 13 additions & 5 deletions compiler/rustc_resolve/src/imports.rs
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Expand Up @@ -781,14 +781,22 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {

let mut imports_to_resolve = mem::take(&mut self.indeterminate_imports);

self.assert_speculative = true;
// SAFETY: This is a "top-level" function used by the macro expansion code, unless some
// weird thing is done, all `tracked` borrows done in the previous call of
// `resolve_imports` are dropped when that call ended.
unsafe { self.speculative_flag.set(true) };
rustc_data_structures::sync::par_for_each_slice(
&mut imports_to_resolve,
|(import, resolution, indeterminate_count)| {
(*resolution, *indeterminate_count) = self.resolve_import(*import);
},
);
self.assert_speculative = false;
// SAFETY: All `untracked` borrows are dropped after the `par_for_each_slice` call,
// as they cannot escape since they are tied to the `CmRefCell` they borrowed from.
Comment thread
petrochenkov marked this conversation as resolved.
//
// Note: Some `CmRefCell`s are arena allocated and thus have the `'ra` lifetime,
// allowing these borrows to escape, but that does not and should not happen.
unsafe { self.speculative_flag.set(false) };

self.write_import_resolutions(&imports_to_resolve);

Expand Down Expand Up @@ -1003,7 +1011,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
pub(crate) fn lint_reexports(&mut self, exported_ambiguities: FxHashSet<Decl<'ra>>) {
for module in &self.local_modules {
for (key, resolution) in self.resolutions(module.to_module()).iter() {
let resolution = resolution.borrow();
let resolution = resolution.borrow(self);
let Some(binding) = resolution.best_decl() else { continue };

// Report "cannot reexport" errors for exotic cases involving macros 2.0
Expand Down Expand Up @@ -1490,7 +1498,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
return None;
} // `use _` is never valid

let resolution = resolution.borrow();
let resolution = resolution.borrow(self);
if let Some(name_binding) = resolution.best_decl() {
match name_binding.kind {
DeclKind::Import { source_decl, .. } => {
Expand Down Expand Up @@ -1800,7 +1808,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
.resolutions(module)
.iter()
.filter_map(|(key, resolution)| {
let res = resolution.borrow();
let res = resolution.borrow(self);
let decl = res.determined_decl()?;
let mut key = *key;
let scope = match key.ident.ctxt.update_unchecked(|ctxt| {
Expand Down
10 changes: 6 additions & 4 deletions compiler/rustc_resolve/src/late/diagnostics.rs
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Expand Up @@ -194,7 +194,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
if key.ident.name != assoc_name {
return None;
}
let resolution = resolution.borrow();
let resolution = resolution.borrow(self.r);
let binding = resolution.best_decl()?;
match binding.res() {
Res::Def(DefKind::AssocTy, def_id) => Some(def_id),
Expand Down Expand Up @@ -1165,7 +1165,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
let find_doc_alias_name = |r: &mut Resolver<'ra, '_>, m: Module<'ra>, item_name: Symbol| {
for resolution in r.resolutions(m).values() {
let Some(did) =
resolution.borrow().best_decl().and_then(|binding| binding.res().opt_def_id())
resolution.borrow(r).best_decl().and_then(|binding| binding.res().opt_def_id())
else {
continue;
};
Expand Down Expand Up @@ -1905,7 +1905,7 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
.resolutions(module)
.iter()
.filter_map(|(key, resolution)| {
let resolution = resolution.borrow();
let resolution = resolution.borrow(self.r);
resolution.best_decl().map(|binding| binding.res()).and_then(|res| {
if filter_fn(res) {
Some((key.ident.name, resolution.orig_ident_span, res))
Expand Down Expand Up @@ -2766,7 +2766,9 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> {
.r
.resolutions(*module)
.iter()
.filter_map(|(key, res)| res.borrow().best_decl().map(|binding| (key, binding.res())))
.filter_map(|(key, res)| {
res.borrow(self.r).best_decl().map(|binding| (key, binding.res()))
})
.filter(|(_, res)| match (kind, res) {
(AssocItemKind::Const(..), Res::Def(DefKind::AssocConst { .. }, _)) => true,
(AssocItemKind::Fn(_), Res::Def(DefKind::AssocFn, _)) => true,
Expand Down
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