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resolve: Refactor obtaining Module from its DefId
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The `Option<Module>` version is supported for the case where we don't know whether the `DefId` refers to a module or not.
Non-local traits and enums are also correctly found now.
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@petrochenkov
petrochenkov committed Sep 24, 2021
1 parent a802188 commit ab834e5
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Showing 6 changed files with 76 additions and 78 deletions.
132 changes: 66 additions & 66 deletions compiler/rustc_resolve/src/build_reduced_graph.rs
View file
Expand Up @@ -93,59 +93,76 @@ impl<'a> Resolver<'a> {
}

/// Walks up the tree of definitions starting at `def_id`,
/// stopping at the first `DefKind::Mod` encountered
fn nearest_parent_mod(&mut self, def_id: DefId) -> Module<'a> {
let def_key = self.cstore().def_key(def_id);

let mut parent_id = DefId {
krate: def_id.krate,
index: def_key.parent.expect("failed to get parent for module"),
};
// The immediate parent may not be a module
// (e.g. `const _: () = { #[path = "foo.rs"] mod foo; };`)
// Walk up the tree until we hit a module or the crate root.
while parent_id.index != CRATE_DEF_INDEX
&& self.cstore().def_kind(parent_id) != DefKind::Mod
{
let parent_def_key = self.cstore().def_key(parent_id);
parent_id.index = parent_def_key.parent.expect("failed to get parent for module");
/// stopping at the first encountered module.
/// Parent block modules for arbitrary def-ids are not recorded for the local crate,
/// and are not preserved in metadata for foreign crates, so block modules are never
/// returned by this function.
///
/// For the local crate ignoring block modules may be incorrect, so use this method with care.
///
/// For foreign crates block modules can be ignored without introducing observable differences,
/// moreover they has to be ignored right now because they are not kept in metadata.
/// Foreign parent modules are used for resolving names used by foreign macros with def-site
/// hygiene, therefore block module ignorability relies on macros with def-site hygiene and
/// block module parents being unreachable from other crates.
/// Reachable macros with block module parents exist due to `#[macro_export] macro_rules!`,
/// but they cannot use def-site hygiene, so the assumption holds
/// (<https://github.com/rust-lang/rust/pull/77984#issuecomment-712445508>).
fn get_nearest_non_block_module(&mut self, mut def_id: DefId) -> Module<'a> {
loop {
match self.get_module(def_id) {
Some(module) => return module,
None => {
def_id.index =
self.def_key(def_id).parent.expect("non-root `DefId` without parent")
}
}
}
self.get_module(parent_id)
}

pub fn get_module(&mut self, def_id: DefId) -> Module<'a> {
// Cache module resolution
if let Some(module) = self.module_map.get(&def_id) {
return *module;
pub fn expect_module(&mut self, def_id: DefId) -> Module<'a> {
self.get_module(def_id).expect("argument `DefId` is not a module")
}

/// If `def_id` refers to a module (in resolver's sense, i.e. a module item, crate root, enum,
/// or trait), then this function returns that module's resolver representation, otherwise it
/// returns `None`.
/// FIXME: `Module`s for local enums and traits are not currently found.
crate fn get_module(&mut self, def_id: DefId) -> Option<Module<'a>> {
if let module @ Some(..) = self.module_map.get(&def_id) {
return module.copied();
}

assert!(!def_id.is_local());
let (name, parent) = if def_id.index == CRATE_DEF_INDEX {
// This is the crate root
(self.cstore().crate_name(def_id.krate), None)
} else {
let def_key = self.cstore().def_key(def_id);
let name = def_key
.disambiguated_data
.data
.get_opt_name()
.expect("given a DefId that wasn't a module");

let parent = Some(self.nearest_parent_mod(def_id));
(name, parent)
};
if !def_id.is_local() {
let def_kind = self.cstore().def_kind(def_id);
match def_kind {
DefKind::Mod | DefKind::Enum | DefKind::Trait => {
let def_key = self.cstore().def_key(def_id);
let parent = def_key.parent.map(|index| {
self.get_nearest_non_block_module(DefId { index, krate: def_id.krate })
});
let name = if def_id.index == CRATE_DEF_INDEX {
self.cstore().crate_name(def_id.krate)
} else {
def_key.disambiguated_data.data.get_opt_name().expect("module without name")
};

// Allocate and return a new module with the information we found
let module = self.arenas.new_module(
parent,
ModuleKind::Def(DefKind::Mod, def_id, name),
self.cstore().module_expansion_untracked(def_id, &self.session),
self.cstore().get_span_untracked(def_id, &self.session),
// FIXME: Account for `#[no_implicit_prelude]` attributes.
parent.map_or(false, |module| module.no_implicit_prelude),
);
self.module_map.insert(def_id, module);
module
let module = self.arenas.new_module(
parent,
ModuleKind::Def(def_kind, def_id, name),
self.cstore().module_expansion_untracked(def_id, &self.session),
self.cstore().get_span_untracked(def_id, &self.session),
// FIXME: Account for `#[no_implicit_prelude]` attributes.
parent.map_or(false, |module| module.no_implicit_prelude),
);
self.module_map.insert(def_id, module);
Some(module)
}
_ => None,
}
} else {
None
}
}

crate fn expn_def_scope(&mut self, expn_id: ExpnId) -> Module<'a> {
Expand All @@ -162,24 +179,7 @@ impl<'a> Resolver<'a> {
if let Some(id) = def_id.as_local() {
self.local_macro_def_scopes[&id]
} else {
// This is not entirely correct - a `macro_rules!` macro may occur
// inside a 'block' module:
//
// ```rust
// const _: () = {
// #[macro_export]
// macro_rules! my_macro {
// () => {};
// }
// `
// We don't record this information for external crates, so
// the module we compute here will be the closest 'mod' item
// (not necesssarily the actual parent of the `macro_rules!`
// macro). `macro_rules!` macros can't use def-site hygiene,
// so this hopefully won't be a problem.
//
// See https://github.com/rust-lang/rust/pull/77984#issuecomment-712445508
self.nearest_parent_mod(def_id)
self.get_nearest_non_block_module(def_id)
}
}

Expand Down Expand Up @@ -708,7 +708,7 @@ impl<'a, 'b> BuildReducedGraphVisitor<'a, 'b> {
local_def_id,
);
self.r.extern_crate_map.insert(local_def_id, crate_id);
self.r.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX })
self.r.expect_module(crate_id.as_def_id())
};

let used = self.process_macro_use_imports(item, module);
Expand Down
3 changes: 1 addition & 2 deletions compiler/rustc_resolve/src/diagnostics.rs
View file
Expand Up @@ -915,8 +915,7 @@ impl<'a> Resolver<'a> {
continue;
}
if let Some(crate_id) = self.crate_loader.maybe_process_path_extern(ident.name) {
let crate_root =
self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
let crate_root = self.expect_module(crate_id.as_def_id());
suggestions.extend(self.lookup_import_candidates_from_module(
lookup_ident,
namespace,
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_resolve/src/late.rs
View file
Expand Up @@ -799,7 +799,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
}

fn with_scope<T>(&mut self, id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
if let Some(module) = self.r.module_map.get(&self.r.local_def_id(id).to_def_id()).copied() {
if let Some(module) = self.r.get_module(self.r.local_def_id(id).to_def_id()) {
// Move down in the graph.
let orig_module = replace(&mut self.parent_scope.module, module);
self.with_rib(ValueNS, ModuleRibKind(module), |this| {
Expand Down
13 changes: 6 additions & 7 deletions compiler/rustc_resolve/src/lib.rs
View file
Expand Up @@ -2167,9 +2167,8 @@ impl<'a> Resolver<'a> {
return self.graph_root;
}
};
let module =
self.get_module(module.def_id().map_or(LOCAL_CRATE, |def_id| def_id.krate).as_def_id());

let module = self
.expect_module(module.def_id().map_or(LOCAL_CRATE, |def_id| def_id.krate).as_def_id());
debug!(
"resolve_crate_root({:?}): got module {:?} ({:?}) (ident.span = {:?})",
ident,
Expand All @@ -2181,10 +2180,10 @@ impl<'a> Resolver<'a> {
}

fn resolve_self(&mut self, ctxt: &mut SyntaxContext, module: Module<'a>) -> Module<'a> {
let mut module = self.get_module(module.nearest_parent_mod());
let mut module = self.expect_module(module.nearest_parent_mod());
while module.span.ctxt().normalize_to_macros_2_0() != *ctxt {
let parent = module.parent.unwrap_or_else(|| self.expn_def_scope(ctxt.remove_mark()));
module = self.get_module(parent.nearest_parent_mod());
module = self.expect_module(parent.nearest_parent_mod());
}
module
}
Expand Down Expand Up @@ -3267,7 +3266,7 @@ impl<'a> Resolver<'a> {
} else {
self.crate_loader.maybe_process_path_extern(ident.name)?
};
let crate_root = self.get_module(DefId { krate: crate_id, index: CRATE_DEF_INDEX });
let crate_root = self.expect_module(crate_id.as_def_id());
Some(
(crate_root, ty::Visibility::Public, DUMMY_SP, LocalExpnId::ROOT)
.to_name_binding(self.arenas),
Expand Down Expand Up @@ -3308,7 +3307,7 @@ impl<'a> Resolver<'a> {
tokens: None,
}
};
let module = self.get_module(module_id);
let module = self.expect_module(module_id);
let parent_scope = &ParentScope::module(module, self);
let res = self.resolve_ast_path(&path, ns, parent_scope).map_err(|_| ())?;
Ok((path, res))
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_resolve/src/macros.rs
View file
Expand Up @@ -240,7 +240,7 @@ impl<'a> ResolverExpand for Resolver<'a> {
);

let parent_scope =
parent_module.map_or(self.empty_module, |def_id| self.get_module(def_id));
parent_module.map_or(self.empty_module, |def_id| self.expect_module(def_id));
self.ast_transform_scopes.insert(expn_id, parent_scope);

expn_id
Expand Down
2 changes: 1 addition & 1 deletion src/librustdoc/passes/collect_intra_doc_links.rs
View file
Expand Up @@ -759,7 +759,7 @@ fn traits_implemented_by(cx: &mut DocContext<'_>, type_: DefId, module: DefId) -
let mut resolver = cx.resolver.borrow_mut();
let in_scope_traits = cx.module_trait_cache.entry(module).or_insert_with(|| {
resolver.access(|resolver| {
let parent_scope = &ParentScope::module(resolver.get_module(module), resolver);
let parent_scope = &ParentScope::module(resolver.expect_module(module), resolver);
resolver
.traits_in_scope(None, parent_scope, SyntaxContext::root(), None)
.into_iter()
Expand Down

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