Completely remove LifetimeScopeForPath.

Author: cjgillot

compiler/rustc_middle/src/middle/resolve_lifetime.rs

@@ -16,19 +16,6 @@ pub enum Region {
     Free(DefId, /* lifetime decl */ DefId),
 }
 
-/// This is used in diagnostics to improve suggestions for missing generic arguments.
-/// It gives information on the type of lifetimes that are in scope for a particular `PathSegment`,
-/// so that we can e.g. suggest elided-lifetimes-in-paths of the form <'_, '_> e.g.
-#[derive(Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable, Debug, HashStable)]
-pub enum LifetimeScopeForPath {
-    /// Contains all lifetime names that are in scope and could possibly be used in generics
-    /// arguments of path.
-    NonElided,
-    /// Information that allows us to suggest args of the form `<'_>` in case
-    /// no generic arguments were provided for a path.
-    Elided,
-}
-
 /// A set containing, at most, one known element.
 /// If two distinct values are inserted into a set, then it
 /// becomes `Many`, which can be used to detect ambiguities.

compiler/rustc_middle/src/query/mod.rs

@@ -1599,11 +1599,6 @@ rustc_queries! {
         desc { "looking up late bound vars" }
     }
 
-    query lifetime_scope_map(_: LocalDefId) -> Option<FxHashMap<ItemLocalId, LifetimeScopeForPath>> {
-        storage(ArenaCacheSelector<'tcx>)
-        desc { "finds the lifetime scope for an HirId of a PathSegment" }
-    }
-
     query visibility(def_id: DefId) -> ty::Visibility {
         desc { |tcx| "computing visibility of `{}`", tcx.def_path_str(def_id) }
         separate_provide_extern

compiler/rustc_middle/src/ty/context.rs

@@ -6,7 +6,7 @@ use crate::hir::place::Place as HirPlace;
 use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::{struct_lint_level, LintDiagnosticBuilder, LintLevelSource};
 use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
-use crate::middle::resolve_lifetime::{self, LifetimeScopeForPath};
+use crate::middle::resolve_lifetime;
 use crate::middle::stability;
 use crate::mir::interpret::{self, Allocation, ConstAllocation, ConstValue, Scalar};
 use crate::mir::{
@@ -2821,10 +2821,6 @@ impl<'tcx> TyCtxt<'tcx> {
         )
     }
 
-    pub fn lifetime_scope(self, id: HirId) -> Option<&'tcx LifetimeScopeForPath> {
-        self.lifetime_scope_map(id.owner).as_ref().and_then(|map| map.get(&id.local_id))
-    }
-
     /// Whether the `def_id` counts as const fn in the current crate, considering all active
     /// feature gates
     pub fn is_const_fn(self, def_id: DefId) -> bool {

compiler/rustc_middle/src/ty/query.rs

@@ -6,9 +6,7 @@ use crate::middle::codegen_fn_attrs::CodegenFnAttrs;
 use crate::middle::exported_symbols::{ExportedSymbol, SymbolExportInfo};
 use crate::middle::lib_features::LibFeatures;
 use crate::middle::privacy::AccessLevels;
-use crate::middle::resolve_lifetime::{
-    LifetimeScopeForPath, ObjectLifetimeDefault, Region, ResolveLifetimes,
-};
+use crate::middle::resolve_lifetime::{ObjectLifetimeDefault, Region, ResolveLifetimes};
 use crate::middle::stability::{self, DeprecationEntry};
 use crate::mir;
 use crate::mir::interpret::GlobalId;

compiler/rustc_resolve/src/late/lifetimes.rs

@@ -8,12 +8,11 @@
 
 use crate::late::diagnostics::{ForLifetimeSpanType, MissingLifetimeSpot};
 use rustc_ast::walk_list;
-use rustc_data_structures::fx::{FxHashMap, FxHashSet, FxIndexMap, FxIndexSet};
+use rustc_data_structures::fx::{FxHashSet, FxIndexMap, FxIndexSet};
 use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{DefIdMap, LocalDefId};
-use rustc_hir::hir_id::ItemLocalId;
 use rustc_hir::intravisit::{self, Visitor};
 use rustc_hir::{GenericArg, GenericParam, LifetimeName, Node};
 use rustc_hir::{GenericParamKind, HirIdMap};
@@ -141,9 +140,6 @@ struct NamedRegionMap {
     // - trait refs
     // - bound types (like `T` in `for<'a> T<'a>: Foo`)
     late_bound_vars: HirIdMap<Vec<ty::BoundVariableKind>>,
-
-    // maps `PathSegment` `HirId`s to lifetime scopes.
-    scope_for_path: Option<FxHashMap<LocalDefId, FxHashMap<ItemLocalId, LifetimeScopeForPath>>>,
 }
 
 pub(crate) struct LifetimeContext<'a, 'tcx> {
@@ -353,10 +349,6 @@ pub fn provide(providers: &mut ty::query::Providers) {
             _ => None,
         },
         late_bound_vars_map: |tcx, id| resolve_lifetimes_for(tcx, id).late_bound_vars.get(&id),
-        lifetime_scope_map: |tcx, id| {
-            let item_id = item_for(tcx, id);
-            do_resolve(tcx, item_id, false, true).scope_for_path.unwrap().remove(&id)
-        },
 
         ..*providers
     };
@@ -397,29 +389,25 @@ fn resolve_lifetimes_trait_definition(
     tcx: TyCtxt<'_>,
     local_def_id: LocalDefId,
 ) -> ResolveLifetimes {
-    convert_named_region_map(do_resolve(tcx, local_def_id, true, false))
+    convert_named_region_map(do_resolve(tcx, local_def_id, true))
 }
 
 /// Computes the `ResolveLifetimes` map that contains data for an entire `Item`.
 /// You should not read the result of this query directly, but rather use
 /// `named_region_map`, `is_late_bound_map`, etc.
 #[tracing::instrument(level = "debug", skip(tcx))]
 fn resolve_lifetimes(tcx: TyCtxt<'_>, local_def_id: LocalDefId) -> ResolveLifetimes {
-    convert_named_region_map(do_resolve(tcx, local_def_id, false, false))
+    convert_named_region_map(do_resolve(tcx, local_def_id, false))
 }
 
 fn do_resolve(
     tcx: TyCtxt<'_>,
     local_def_id: LocalDefId,
     trait_definition_only: bool,
-    with_scope_for_path: bool,
 ) -> NamedRegionMap {
     let item = tcx.hir().expect_item(local_def_id);
-    let mut named_region_map = NamedRegionMap {
-        defs: Default::default(),
-        late_bound_vars: Default::default(),
-        scope_for_path: with_scope_for_path.then(|| Default::default()),
-    };
+    let mut named_region_map =
+        NamedRegionMap { defs: Default::default(), late_bound_vars: Default::default() };
     let mut visitor = LifetimeContext {
         tcx,
         map: &mut named_region_map,
@@ -515,24 +503,6 @@ fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::
     }
 }
 
-#[tracing::instrument(level = "debug")]
-fn get_lifetime_scopes_for_path(mut scope: &Scope<'_>) -> LifetimeScopeForPath {
-    loop {
-        match scope {
-            Scope::Elision { elide: Elide::Exact(_), .. } => return LifetimeScopeForPath::Elided,
-            Scope::Root => return LifetimeScopeForPath::NonElided,
-            Scope::Binder { s, .. }
-            | Scope::Body { s, .. }
-            | Scope::ObjectLifetimeDefault { s, .. }
-            | Scope::Supertrait { s, .. }
-            | Scope::TraitRefBoundary { s, .. }
-            | Scope::Elision { s, .. } => {
-                scope = s;
-            }
-        }
-    }
-}
-
 impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
     /// Returns the binders in scope and the type of `Binder` that should be created for a poly trait ref.
     fn poly_trait_ref_binder_info(&mut self) -> (Vec<ty::BoundVariableKind>, BinderScopeType) {
@@ -1172,51 +1142,13 @@ impl<'a, 'tcx> Visitor<'tcx> for LifetimeContext<'a, 'tcx> {
         }
     }
 
-    fn visit_assoc_type_binding(&mut self, type_binding: &'tcx hir::TypeBinding<'_>) {
-        let scope = self.scope;
-        if let Some(scope_for_path) = self.map.scope_for_path.as_mut() {
-            // We add lifetime scope information for `Ident`s in associated type bindings and use
-            // the `HirId` of the type binding as the key in `LifetimeMap`
-            let lifetime_scope = get_lifetime_scopes_for_path(scope);
-            let map = scope_for_path.entry(type_binding.hir_id.owner).or_default();
-            map.insert(type_binding.hir_id.local_id, lifetime_scope);
-        }
-        hir::intravisit::walk_assoc_type_binding(self, type_binding);
-    }
-
     fn visit_path(&mut self, path: &'tcx hir::Path<'tcx>, _: hir::HirId) {
         for (i, segment) in path.segments.iter().enumerate() {
             let depth = path.segments.len() - i - 1;
             if let Some(ref args) = segment.args {
                 self.visit_segment_args(path.res, depth, args);
             }
-
-            let scope = self.scope;
-            if let Some(scope_for_path) = self.map.scope_for_path.as_mut() {
-                // Add lifetime scope information to path segment. Note we cannot call `visit_path_segment`
-                // here because that call would yield to resolution problems due to `walk_path_segment`
-                // being called, which processes the path segments generic args, which we have already
-                // processed using `visit_segment_args`.
-                let lifetime_scope = get_lifetime_scopes_for_path(scope);
-                if let Some(hir_id) = segment.hir_id {
-                    let map = scope_for_path.entry(hir_id.owner).or_default();
-                    map.insert(hir_id.local_id, lifetime_scope);
-                }
-            }
-        }
-    }
-
-    fn visit_path_segment(&mut self, path_span: Span, path_segment: &'tcx hir::PathSegment<'tcx>) {
-        let scope = self.scope;
-        if let Some(scope_for_path) = self.map.scope_for_path.as_mut() {
-            let lifetime_scope = get_lifetime_scopes_for_path(scope);
-            if let Some(hir_id) = path_segment.hir_id {
-                let map = scope_for_path.entry(hir_id.owner).or_default();
-                map.insert(hir_id.local_id, lifetime_scope);
-            }
         }
-
-        intravisit::walk_path_segment(self, path_span, path_segment);
     }
 
     fn visit_fn_decl(&mut self, fd: &'tcx hir::FnDecl<'tcx>) {
@@ -2480,16 +2412,6 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
             }
         };
 
-        // If we specifically need the `scope_for_path` map, then we're in the
-        // diagnostic pass and we don't want to emit more errors.
-        if self.map.scope_for_path.is_some() {
-            self.tcx.sess.delay_span_bug(
-                rustc_span::DUMMY_SP,
-                "Encountered unexpected errors during diagnostics related part",
-            );
-            return;
-        }
-
         let mut spans: Vec<_> = lifetime_refs.iter().map(|lt| lt.span).collect();
         spans.sort();
         let mut spans_dedup = spans.clone();

compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs

@@ -5,7 +5,6 @@ use rustc_errors::{
 };
 use rustc_hir as hir;
 use rustc_middle::hir::map::fn_sig;
-use rustc_middle::middle::resolve_lifetime::LifetimeScopeForPath;
 use rustc_middle::ty::{self as ty, AssocItems, AssocKind, TyCtxt};
 use rustc_session::Session;
 use rustc_span::def_id::DefId;
@@ -299,13 +298,6 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
         debug!(?path_hir_id);
 
         if let Some(path_hir_id) = path_hir_id {
-            // We first try to get lifetime name suggestions from scope or elision information.
-            // If none is available we use the parameter definitions
-            if let Some(LifetimeScopeForPath::Elided) = self.tcx.lifetime_scope(path_hir_id) {
-                // Use suggestions of the form `<'_, '_>` in case lifetime can be elided
-                return ["'_"].repeat(num_params_to_take).join(",");
-            }
-
             let mut ret = Vec::new();
             for (id, node) in self.tcx.hir().parent_iter(path_hir_id) {
                 debug!(?id);