From fae18826eb1a440a5e9c3e496bab9f4daa0f0087 Mon Sep 17 00:00:00 2001 From: Noah Lev Date: Thu, 15 Aug 2024 14:36:10 -0700 Subject: [PATCH] Fix anon const def-creation when macros are involved Ever since #125915, some `ast::AnonConst`s turn into `hir::ConstArgKind::Path`s, which don't have associated `DefId`s. To deal with the fact that we don't have resolution information in `DefCollector`, we decided to implement a process where if the anon const *appeared* to be trivial (i.e., `N` or `{ N }`), we would avoid creating a def for it in `DefCollector`. If later, in AST lowering, we realized it turned out to be a unit struct literal, or we were lowering it to something that didn't use `hir::ConstArg`, we'd create its def there. However, let's say we have a macro `m!()` that expands to a reference to a free constant `FOO`. If we use `m!()` in the body of an anon const (e.g., `Foo<{ m!() }>`), then in def collection, it appears to be a nontrivial anon const and we create a def. But the macro expands to something that looks like a trivial const arg, but is not, so in AST lowering we "fix" the mistake we assumed def collection made and create a def for it. This causes a duplicate definition ICE. The long-term fix for this is to delay the creation of defs for all expression-like nodes until AST lowering (see #128844 for an incomplete attempt at this). This would avoid issues like this one that are caused by hacky workarounds. However, doing this uncovers a pre-existing bug with opaque types that is quite involved to fix (see #129023). In the meantime, this PR fixes the bug by delaying def creation for anon consts whose bodies are macro invocations until after we expand the macro and know what is inside it. This is accomplished by adding information to create the anon const's def to the data in `Resolver.invocation_parents`. --- compiler/rustc_ast/src/ast.rs | 20 ++-- compiler/rustc_resolve/src/def_collector.rs | 110 ++++++++++++++------ compiler/rustc_resolve/src/lib.rs | 28 ++++- compiler/rustc_resolve/src/macros.rs | 16 +-- 4 files changed, 122 insertions(+), 52 deletions(-) diff --git a/compiler/rustc_ast/src/ast.rs b/compiler/rustc_ast/src/ast.rs index 85d38a0e28b0f..1507cf1dba65c 100644 --- a/compiler/rustc_ast/src/ast.rs +++ b/compiler/rustc_ast/src/ast.rs @@ -1188,14 +1188,7 @@ impl Expr { /// /// Does not ensure that the path resolves to a const param, the caller should check this. pub fn is_potential_trivial_const_arg(&self) -> bool { - let this = if let ExprKind::Block(block, None) = &self.kind - && let [stmt] = block.stmts.as_slice() - && let StmtKind::Expr(expr) = &stmt.kind - { - expr - } else { - self - }; + let this = self.maybe_unwrap_block(); if let ExprKind::Path(None, path) = &this.kind && path.is_potential_trivial_const_arg() @@ -1206,6 +1199,17 @@ impl Expr { } } + pub fn maybe_unwrap_block(&self) -> &Expr { + if let ExprKind::Block(block, None) = &self.kind + && let [stmt] = block.stmts.as_slice() + && let StmtKind::Expr(expr) = &stmt.kind + { + expr + } else { + self + } + } + pub fn to_bound(&self) -> Option { match &self.kind { ExprKind::Path(None, path) => Some(GenericBound::Trait( diff --git a/compiler/rustc_resolve/src/def_collector.rs b/compiler/rustc_resolve/src/def_collector.rs index 0fedb998463a2..dc1aa0a42f8e1 100644 --- a/compiler/rustc_resolve/src/def_collector.rs +++ b/compiler/rustc_resolve/src/def_collector.rs @@ -12,15 +12,23 @@ use rustc_span::symbol::{kw, sym, Symbol}; use rustc_span::Span; use tracing::debug; -use crate::{ImplTraitContext, Resolver}; +use crate::{ImplTraitContext, InvocationParent, PendingAnonConstInfo, Resolver}; pub(crate) fn collect_definitions( resolver: &mut Resolver<'_, '_>, fragment: &AstFragment, expansion: LocalExpnId, ) { - let (parent_def, impl_trait_context, in_attr) = resolver.invocation_parents[&expansion]; - let mut visitor = DefCollector { resolver, parent_def, expansion, impl_trait_context, in_attr }; + let InvocationParent { parent_def, pending_anon_const_info, impl_trait_context, in_attr } = + resolver.invocation_parents[&expansion]; + let mut visitor = DefCollector { + resolver, + parent_def, + pending_anon_const_info, + expansion, + impl_trait_context, + in_attr, + }; fragment.visit_with(&mut visitor); } @@ -28,6 +36,13 @@ pub(crate) fn collect_definitions( struct DefCollector<'a, 'b, 'tcx> { resolver: &'a mut Resolver<'b, 'tcx>, parent_def: LocalDefId, + /// If we have an anon const that consists of a macro invocation, e.g. `Foo<{ m!() }>`, + /// we need to wait until we know what the macro expands to before we create the def for + /// the anon const. That's because we lower some anon consts into `hir::ConstArgKind::Path`, + /// which don't have defs. + /// + /// See `Self::visit_anon_const()`. + pending_anon_const_info: Option, impl_trait_context: ImplTraitContext, in_attr: bool, expansion: LocalExpnId, @@ -111,10 +126,16 @@ impl<'a, 'b, 'tcx> DefCollector<'a, 'b, 'tcx> { fn visit_macro_invoc(&mut self, id: NodeId) { let id = id.placeholder_to_expn_id(); - let old_parent = self - .resolver - .invocation_parents - .insert(id, (self.parent_def, self.impl_trait_context, self.in_attr)); + let pending_anon_const_info = self.pending_anon_const_info.take(); + let old_parent = self.resolver.invocation_parents.insert( + id, + InvocationParent { + parent_def: self.parent_def, + pending_anon_const_info, + impl_trait_context: self.impl_trait_context, + in_attr: self.in_attr, + }, + ); assert!(old_parent.is_none(), "parent `LocalDefId` is reset for an invocation"); } } @@ -326,46 +347,67 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> { } fn visit_anon_const(&mut self, constant: &'a AnonConst) { - if self.resolver.tcx.features().const_arg_path - && constant.value.is_potential_trivial_const_arg() - { + if self.resolver.tcx.features().const_arg_path { // HACK(min_generic_const_args): don't create defs for anon consts if we think they will // later be turned into ConstArgKind::Path's. because this is before resolve is done, we // may accidentally identify a construction of a unit struct as a param and not create a // def. we'll then create a def later in ast lowering in this case. the parent of nested // items will be messed up, but that's ok because there can't be any if we're just looking // for bare idents. - visit::walk_anon_const(self, constant) - } else { - let def = - self.create_def(constant.id, kw::Empty, DefKind::AnonConst, constant.value.span); - self.with_parent(def, |this| visit::walk_anon_const(this, constant)); + + if matches!(constant.value.maybe_unwrap_block().kind, ExprKind::MacCall(..)) { + // See self.pending_anon_const_info for explanation + self.pending_anon_const_info = + Some(PendingAnonConstInfo { id: constant.id, span: constant.value.span }); + return visit::walk_anon_const(self, constant); + } else if constant.value.is_potential_trivial_const_arg() { + return visit::walk_anon_const(self, constant); + } } + + let def = self.create_def(constant.id, kw::Empty, DefKind::AnonConst, constant.value.span); + self.with_parent(def, |this| visit::walk_anon_const(this, constant)); } fn visit_expr(&mut self, expr: &'a Expr) { - let parent_def = match expr.kind { - ExprKind::MacCall(..) => return self.visit_macro_invoc(expr.id), - ExprKind::Closure(..) | ExprKind::Gen(..) => { - self.create_def(expr.id, kw::Empty, DefKind::Closure, expr.span) - } - ExprKind::ConstBlock(ref constant) => { - for attr in &expr.attrs { - visit::walk_attribute(self, attr); - } - let def = self.create_def( - constant.id, - kw::Empty, - DefKind::InlineConst, - constant.value.span, - ); - self.with_parent(def, |this| visit::walk_anon_const(this, constant)); - return; + if matches!(expr.kind, ExprKind::MacCall(..)) { + return self.visit_macro_invoc(expr.id); + } + + let grandparent_def = if let Some(pending_anon) = self.pending_anon_const_info.take() { + // See self.pending_anon_const_info for explanation + if !expr.is_potential_trivial_const_arg() { + self.create_def(pending_anon.id, kw::Empty, DefKind::AnonConst, pending_anon.span) + } else { + self.parent_def } - _ => self.parent_def, + } else { + self.parent_def }; - self.with_parent(parent_def, |this| visit::walk_expr(this, expr)); + self.with_parent(grandparent_def, |this| { + let parent_def = match expr.kind { + ExprKind::Closure(..) | ExprKind::Gen(..) => { + this.create_def(expr.id, kw::Empty, DefKind::Closure, expr.span) + } + ExprKind::ConstBlock(ref constant) => { + for attr in &expr.attrs { + visit::walk_attribute(this, attr); + } + let def = this.create_def( + constant.id, + kw::Empty, + DefKind::InlineConst, + constant.value.span, + ); + this.with_parent(def, |this| visit::walk_anon_const(this, constant)); + return; + } + _ => this.parent_def, + }; + + this.with_parent(parent_def, |this| visit::walk_expr(this, expr)) + }) } fn visit_ty(&mut self, ty: &'a Ty) { diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs index 8ffd00d1b2e60..6ec72649ce32e 100644 --- a/compiler/rustc_resolve/src/lib.rs +++ b/compiler/rustc_resolve/src/lib.rs @@ -171,6 +171,29 @@ impl<'a> ParentScope<'a> { } } +#[derive(Copy, Debug, Clone)] +struct InvocationParent { + parent_def: LocalDefId, + pending_anon_const_info: Option, + impl_trait_context: ImplTraitContext, + in_attr: bool, +} + +impl InvocationParent { + const ROOT: Self = Self { + parent_def: CRATE_DEF_ID, + pending_anon_const_info: None, + impl_trait_context: ImplTraitContext::Existential, + in_attr: false, + }; +} + +#[derive(Copy, Debug, Clone)] +struct PendingAnonConstInfo { + id: NodeId, + span: Span, +} + #[derive(Copy, Debug, Clone)] enum ImplTraitContext { Existential, @@ -1144,7 +1167,7 @@ pub struct Resolver<'a, 'tcx> { /// When collecting definitions from an AST fragment produced by a macro invocation `ExpnId` /// we know what parent node that fragment should be attached to thanks to this table, /// and how the `impl Trait` fragments were introduced. - invocation_parents: FxHashMap, + invocation_parents: FxHashMap, /// Some way to know that we are in a *trait* impl in `visit_assoc_item`. /// FIXME: Replace with a more general AST map (together with some other fields). @@ -1381,8 +1404,7 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> { node_id_to_def_id.insert(CRATE_NODE_ID, crate_feed); let mut invocation_parents = FxHashMap::default(); - invocation_parents - .insert(LocalExpnId::ROOT, (CRATE_DEF_ID, ImplTraitContext::Existential, false)); + invocation_parents.insert(LocalExpnId::ROOT, InvocationParent::ROOT); let mut extern_prelude: FxHashMap> = tcx .sess diff --git a/compiler/rustc_resolve/src/macros.rs b/compiler/rustc_resolve/src/macros.rs index 7203fbe4a0c18..d6afd01f48748 100644 --- a/compiler/rustc_resolve/src/macros.rs +++ b/compiler/rustc_resolve/src/macros.rs @@ -42,9 +42,9 @@ use crate::errors::{ use crate::imports::Import; use crate::Namespace::*; use crate::{ - BindingKey, BuiltinMacroState, DeriveData, Determinacy, Finalize, MacroData, ModuleKind, - ModuleOrUniformRoot, NameBinding, NameBindingKind, ParentScope, PathResult, ResolutionError, - Resolver, ScopeSet, Segment, ToNameBinding, Used, + BindingKey, BuiltinMacroState, DeriveData, Determinacy, Finalize, InvocationParent, MacroData, + ModuleKind, ModuleOrUniformRoot, NameBinding, NameBindingKind, ParentScope, PathResult, + ResolutionError, Resolver, ScopeSet, Segment, ToNameBinding, Used, }; type Res = def::Res; @@ -183,7 +183,7 @@ impl<'a, 'tcx> ResolverExpand for Resolver<'a, 'tcx> { } fn invocation_parent(&self, id: LocalExpnId) -> LocalDefId { - self.invocation_parents[&id].0 + self.invocation_parents[&id].parent_def } fn resolve_dollar_crates(&mut self) { @@ -303,12 +303,12 @@ impl<'a, 'tcx> ResolverExpand for Resolver<'a, 'tcx> { .invocation_parents .get(&invoc_id) .or_else(|| self.invocation_parents.get(&eager_expansion_root)) - .filter(|&&(mod_def_id, _, in_attr)| { + .filter(|&&InvocationParent { parent_def: mod_def_id, in_attr, .. }| { in_attr && invoc.fragment_kind == AstFragmentKind::Expr && self.tcx.def_kind(mod_def_id) == DefKind::Mod }) - .map(|&(mod_def_id, ..)| mod_def_id); + .map(|&InvocationParent { parent_def: mod_def_id, .. }| mod_def_id); let (ext, res) = self.smart_resolve_macro_path( path, kind, @@ -951,7 +951,9 @@ impl<'a, 'tcx> Resolver<'a, 'tcx> { let node_id = self .invocation_parents .get(&parent_scope.expansion) - .map_or(ast::CRATE_NODE_ID, |id| self.def_id_to_node_id[id.0]); + .map_or(ast::CRATE_NODE_ID, |parent| { + self.def_id_to_node_id[parent.parent_def] + }); self.lint_buffer.buffer_lint( LEGACY_DERIVE_HELPERS, node_id,