From cde0374d9301090c9b6b93bb033c07b04b55ab73 Mon Sep 17 00:00:00 2001 From: Vadim Petrochenkov Date: Thu, 31 Jul 2025 19:17:51 +0300 Subject: [PATCH 1/4] resolve: Clarify extern prelude insertion for `extern crate` items --- Cargo.lock | 1 + compiler/rustc_resolve/Cargo.toml | 1 + .../rustc_resolve/src/build_reduced_graph.rs | 42 +++++++++++-------- 3 files changed, 26 insertions(+), 18 deletions(-) diff --git a/Cargo.lock b/Cargo.lock index c1076f05ef129..e0f3a9d1ff1a5 100644 --- a/Cargo.lock +++ b/Cargo.lock @@ -4552,6 +4552,7 @@ name = "rustc_resolve" version = "0.0.0" dependencies = [ "bitflags", + "indexmap", "itertools", "pulldown-cmark", "rustc_arena", diff --git a/compiler/rustc_resolve/Cargo.toml b/compiler/rustc_resolve/Cargo.toml index 1238ce0125a1a..19854502cc308 100644 --- a/compiler/rustc_resolve/Cargo.toml +++ b/compiler/rustc_resolve/Cargo.toml @@ -6,6 +6,7 @@ edition = "2024" [dependencies] # tidy-alphabetical-start bitflags = "2.4.1" +indexmap = "2.4.0" itertools = "0.12" pulldown-cmark = { version = "0.11", features = ["html"], default-features = false } rustc_arena = { path = "../rustc_arena" } diff --git a/compiler/rustc_resolve/src/build_reduced_graph.rs b/compiler/rustc_resolve/src/build_reduced_graph.rs index 7912345ec56ac..a665dd9789902 100644 --- a/compiler/rustc_resolve/src/build_reduced_graph.rs +++ b/compiler/rustc_resolve/src/build_reduced_graph.rs @@ -968,7 +968,7 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> { } self.r.potentially_unused_imports.push(import); let imported_binding = self.r.import(binding, import); - if parent == self.r.graph_root { + if ident.name != kw::Underscore && parent == self.r.graph_root { let ident = ident.normalize_to_macros_2_0(); if let Some(entry) = self.r.extern_prelude.get(&ident) && expansion != LocalExpnId::ROOT @@ -984,23 +984,29 @@ impl<'a, 'ra, 'tcx> BuildReducedGraphVisitor<'a, 'ra, 'tcx> { // more details: https://github.com/rust-lang/rust/pull/111761 return; } - let entry = self.r.extern_prelude.entry(ident).or_insert(ExternPreludeEntry { - binding: Cell::new(None), - introduced_by_item: true, - }); - if orig_name.is_some() { - entry.introduced_by_item = true; - } - // Binding from `extern crate` item in source code can replace - // a binding from `--extern` on command line here. - if !entry.is_import() { - entry.binding.set(Some(imported_binding)); - } else if ident.name != kw::Underscore { - self.r.dcx().span_delayed_bug( - item.span, - format!("it had been define the external module '{ident}' multiple times"), - ); - } + + use indexmap::map::Entry; + match self.r.extern_prelude.entry(ident) { + Entry::Occupied(mut occupied) => { + let entry = occupied.get_mut(); + if let Some(old_binding) = entry.binding.get() + && old_binding.is_import() + { + let msg = format!("extern crate `{ident}` already in extern prelude"); + self.r.tcx.dcx().span_delayed_bug(item.span, msg); + } else { + // Binding from `extern crate` item in source code can replace + // a binding from `--extern` on command line here. + entry.binding.set(Some(imported_binding)); + entry.introduced_by_item = orig_name.is_some(); + } + entry + } + Entry::Vacant(vacant) => vacant.insert(ExternPreludeEntry { + binding: Cell::new(Some(imported_binding)), + introduced_by_item: true, + }), + }; } self.r.define_binding_local(parent, ident, TypeNS, imported_binding); } From 2f7a2fa00fd06f9a1dcd51891b11a255cbf9d32b Mon Sep 17 00:00:00 2001 From: Vadim Petrochenkov Date: Thu, 31 Jul 2025 19:33:12 +0300 Subject: [PATCH 2/4] resolve: Do not add erroneous names to extern prelude --- compiler/rustc_resolve/src/lib.rs | 21 +++++++++++++-------- 1 file changed, 13 insertions(+), 8 deletions(-) diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs index a70ae4fd57a09..17ca2ef7743d8 100644 --- a/compiler/rustc_resolve/src/lib.rs +++ b/compiler/rustc_resolve/src/lib.rs @@ -1487,13 +1487,23 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { let mut invocation_parents = FxHashMap::default(); invocation_parents.insert(LocalExpnId::ROOT, InvocationParent::ROOT); - let mut extern_prelude: FxIndexMap> = tcx + let mut extern_prelude: FxIndexMap<_, _> = tcx .sess .opts .externs .iter() - .filter(|(_, entry)| entry.add_prelude) - .map(|(name, _)| (Ident::from_str(name), Default::default())) + .filter_map(|(name, entry)| { + // Make sure `self`, `super`, `_` etc do not get into extern prelude. + // FIXME: reject `--extern self` and similar in option parsing instead. + if entry.add_prelude + && let name = Symbol::intern(name) + && name.can_be_raw() + { + Some((Ident::with_dummy_span(name), Default::default())) + } else { + None + } + }) .collect(); if !attr::contains_name(attrs, sym::no_core) { @@ -2168,11 +2178,6 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { } fn extern_prelude_get(&mut self, ident: Ident, finalize: bool) -> Option> { - if ident.is_path_segment_keyword() { - // Make sure `self`, `super` etc produce an error when passed to here. - return None; - } - let norm_ident = ident.normalize_to_macros_2_0(); let binding = self.extern_prelude.get(&norm_ident).cloned().and_then(|entry| { Some(if let Some(binding) = entry.binding.get() { From 73096965fbac485a83033516cf61645889700a71 Mon Sep 17 00:00:00 2001 From: Vadim Petrochenkov Date: Thu, 31 Jul 2025 19:51:51 +0300 Subject: [PATCH 3/4] resolve: Avoid double table lookup in `extern_prelude_get` Do not write dummy bindings to extern prelude. Use more precise `Used::Scope` while recording use and remove now redundant `introduced_by_item` check. --- compiler/rustc_resolve/src/lib.rs | 51 ++++++++++++++++++------------- 1 file changed, 29 insertions(+), 22 deletions(-) diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs index 17ca2ef7743d8..bdac1b4675a08 100644 --- a/compiler/rustc_resolve/src/lib.rs +++ b/compiler/rustc_resolve/src/lib.rs @@ -2178,35 +2178,42 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { } fn extern_prelude_get(&mut self, ident: Ident, finalize: bool) -> Option> { - let norm_ident = ident.normalize_to_macros_2_0(); - let binding = self.extern_prelude.get(&norm_ident).cloned().and_then(|entry| { - Some(if let Some(binding) = entry.binding.get() { + let mut record_use = None; + let entry = self.extern_prelude.get(&ident.normalize_to_macros_2_0()); + let binding = entry.and_then(|entry| match entry.binding.get() { + Some(binding) if binding.is_import() => { if finalize { - if !entry.is_import() { - self.cstore_mut().process_path_extern(self.tcx, ident.name, ident.span); - } else if entry.introduced_by_item { - self.record_use(ident, binding, Used::Other); - } + record_use = Some(binding); } - binding - } else { + Some(binding) + } + Some(binding) => { + if finalize { + self.cstore_mut().process_path_extern(self.tcx, ident.name, ident.span); + } + Some(binding) + } + None => { let crate_id = if finalize { - let Some(crate_id) = - self.cstore_mut().process_path_extern(self.tcx, ident.name, ident.span) - else { - return Some(self.dummy_binding); - }; - crate_id + self.cstore_mut().process_path_extern(self.tcx, ident.name, ident.span) } else { - self.cstore_mut().maybe_process_path_extern(self.tcx, ident.name)? + self.cstore_mut().maybe_process_path_extern(self.tcx, ident.name) }; - let res = Res::Def(DefKind::Mod, crate_id.as_def_id()); - self.arenas.new_pub_res_binding(res, DUMMY_SP, LocalExpnId::ROOT) - }) + match crate_id { + Some(crate_id) => { + let res = Res::Def(DefKind::Mod, crate_id.as_def_id()); + let binding = + self.arenas.new_pub_res_binding(res, DUMMY_SP, LocalExpnId::ROOT); + entry.binding.set(Some(binding)); + Some(binding) + } + None => finalize.then_some(self.dummy_binding), + } + } }); - if let Some(entry) = self.extern_prelude.get(&norm_ident) { - entry.binding.set(binding); + if let Some(binding) = record_use { + self.record_use(ident, binding, Used::Scope); } binding From e58e6f857f1335ef2436cb7bf3a4a55ddfc79387 Mon Sep 17 00:00:00 2001 From: Vadim Petrochenkov Date: Thu, 31 Jul 2025 20:33:33 +0300 Subject: [PATCH 4/4] resolve: Cleanup some uses of extern prelude in diagnostics --- compiler/rustc_resolve/src/diagnostics.rs | 4 ++-- compiler/rustc_resolve/src/late/diagnostics.rs | 17 ++++------------- 2 files changed, 6 insertions(+), 15 deletions(-) diff --git a/compiler/rustc_resolve/src/diagnostics.rs b/compiler/rustc_resolve/src/diagnostics.rs index 3af69b28780d0..c80f8106049a6 100644 --- a/compiler/rustc_resolve/src/diagnostics.rs +++ b/compiler/rustc_resolve/src/diagnostics.rs @@ -1098,7 +1098,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { } } Scope::ExternPrelude => { - suggestions.extend(this.extern_prelude.iter().filter_map(|(ident, _)| { + suggestions.extend(this.extern_prelude.keys().filter_map(|ident| { let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()); filter_fn(res).then_some(TypoSuggestion::typo_from_ident(*ident, res)) })); @@ -1411,7 +1411,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> { ); if lookup_ident.span.at_least_rust_2018() { - for ident in self.extern_prelude.clone().into_keys() { + for &ident in self.extern_prelude.keys() { if ident.span.from_expansion() { // Idents are adjusted to the root context before being // resolved in the extern prelude, so reporting this to the diff --git a/compiler/rustc_resolve/src/late/diagnostics.rs b/compiler/rustc_resolve/src/late/diagnostics.rs index 98e48664e6816..efafb2494c20b 100644 --- a/compiler/rustc_resolve/src/late/diagnostics.rs +++ b/compiler/rustc_resolve/src/late/diagnostics.rs @@ -2477,19 +2477,10 @@ impl<'ast, 'ra, 'tcx> LateResolutionVisitor<'_, 'ast, 'ra, 'tcx> { } else { // Items from the prelude if !module.no_implicit_prelude { - let extern_prelude = self.r.extern_prelude.clone(); - names.extend(extern_prelude.iter().flat_map(|(ident, _)| { - self.r - .cstore_mut() - .maybe_process_path_extern(self.r.tcx, ident.name) - .and_then(|crate_id| { - let crate_mod = - Res::Def(DefKind::Mod, crate_id.as_def_id()); - - filter_fn(crate_mod).then(|| { - TypoSuggestion::typo_from_ident(*ident, crate_mod) - }) - }) + names.extend(self.r.extern_prelude.keys().flat_map(|ident| { + let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id()); + filter_fn(res) + .then_some(TypoSuggestion::typo_from_ident(*ident, res)) })); if let Some(prelude) = self.r.prelude {