Auto merge of #60544 - petrochenkov:parder, r=eddyb

Rename `PathResolution` to `PartialRes`

Don't use `PartialRes` when `Res` is enough.
Rename `Res::kind_name` to `Res::descr` for consistency.
Remove `Res::Label`, paths can never resolve to labels.

Some further cleanup after https://github.com/rust-lang/rust/pull/60462
r? @EddyB

src/librustc/hir/def.rs

 use crate::hir::def_id::DefId;
-use crate::util::nodemap::{NodeMap, DefIdMap};
+use crate::util::nodemap::DefIdMap;
 use syntax::ast;
 use syntax::ext::base::MacroKind;
 use syntax::ast::NodeId;
@@ -142,7 +142,6 @@ pub enum Res<Id = hir::HirId> {
     Upvar(Id,           // `HirId` of closed over local
           usize,        // index in the `freevars` list of the closure
           ast::NodeId), // expr node that creates the closure
-    Label(ast::NodeId),
 
     // Macro namespace
     NonMacroAttr(NonMacroAttrKind), // e.g., `#[inline]` or `#[rustfmt::skip]`
@@ -151,7 +150,9 @@ pub enum Res<Id = hir::HirId> {
     Err,
 }
 
-/// The result of resolving a path before lowering to HIR.
+/// The result of resolving a path before lowering to HIR,
+/// with "module" segments resolved and associated item
+/// segments deferred to type checking.
 /// `base_res` is the resolution of the resolved part of the
 /// path, `unresolved_segments` is the number of unresolved
 /// segments.
@@ -166,19 +167,21 @@ pub enum Res<Id = hir::HirId> {
 ///       base_res        unresolved_segments = 2
 /// ```
 #[derive(Copy, Clone, Debug)]
-pub struct PathResolution {
+pub struct PartialRes {
     base_res: Res<NodeId>,
     unresolved_segments: usize,
 }
 
-impl PathResolution {
-    pub fn new(res: Res<NodeId>) -> Self {
-        PathResolution { base_res: res, unresolved_segments: 0 }
+impl PartialRes {
+    #[inline]
+    pub fn new(base_res: Res<NodeId>) -> Self {
+        PartialRes { base_res, unresolved_segments: 0 }
     }
 
-    pub fn with_unresolved_segments(res: Res<NodeId>, mut unresolved_segments: usize) -> Self {
-        if res == Res::Err { unresolved_segments = 0 }
-        PathResolution { base_res: res, unresolved_segments: unresolved_segments }
+    #[inline]
+    pub fn with_unresolved_segments(base_res: Res<NodeId>, mut unresolved_segments: usize) -> Self {
+        if base_res == Res::Err { unresolved_segments = 0 }
+        PartialRes { base_res, unresolved_segments }
     }
 
     #[inline]
@@ -269,17 +272,10 @@ pub fn present_items(self) -> impl Iterator<Item=T> {
     }
 }
 
-/// Definition mapping
-pub type ResMap = NodeMap<PathResolution>;
-
 /// This is the replacement export map. It maps a module to all of the exports
 /// within.
 pub type ExportMap<Id> = DefIdMap<Vec<Export<Id>>>;
 
-/// Map used to track the `use` statements within a scope, matching it with all the items in every
-/// namespace.
-pub type ImportMap = NodeMap<PerNS<Option<PathResolution>>>;
-
 #[derive(Copy, Clone, Debug, RustcEncodable, RustcDecodable, HashStable)]
 pub struct Export<Id> {
     /// The name of the target.
@@ -352,7 +348,6 @@ pub fn opt_def_id(&self) -> Option<DefId> {
 
             Res::Local(..) |
             Res::Upvar(..) |
-            Res::Label(..)  |
             Res::PrimTy(..) |
             Res::SelfTy(..) |
             Res::SelfCtor(..) |
@@ -373,14 +368,13 @@ pub fn mod_def_id(&self) -> Option<DefId> {
     }
 
     /// A human readable name for the res kind ("function", "module", etc.).
-    pub fn kind_name(&self) -> &'static str {
+    pub fn descr(&self) -> &'static str {
         match *self {
             Res::Def(kind, _) => kind.descr(),
             Res::SelfCtor(..) => "self constructor",
             Res::PrimTy(..) => "builtin type",
             Res::Local(..) => "local variable",
             Res::Upvar(..) => "closure capture",
-            Res::Label(..) => "label",
             Res::SelfTy(..) => "self type",
             Res::ToolMod => "tool module",
             Res::NonMacroAttr(attr_kind) => attr_kind.descr(),
@@ -408,7 +402,6 @@ pub fn map_id<R>(self, mut map: impl FnMut(Id) -> R) -> Res<R> {
                 index,
                 closure
             ),
-            Res::Label(id) => Res::Label(id),
             Res::SelfTy(a, b) => Res::SelfTy(a, b),
             Res::ToolMod => Res::ToolMod,
             Res::NonMacroAttr(attr_kind) => Res::NonMacroAttr(attr_kind),

src/librustc/hir/lowering.rs

@@ -37,7 +37,7 @@
 use crate::hir::HirVec;
 use crate::hir::map::{DefKey, DefPathData, Definitions};
 use crate::hir::def_id::{DefId, DefIndex, DefIndexAddressSpace, CRATE_DEF_INDEX};
-use crate::hir::def::{Res, DefKind, PathResolution, PerNS};
+use crate::hir::def::{Res, DefKind, PartialRes, PerNS};
 use crate::hir::{GenericArg, ConstArg};
 use crate::lint::builtin::{self, PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
                     ELIDED_LIFETIMES_IN_PATHS};
@@ -145,11 +145,14 @@ fn resolve_hir_path(
         is_value: bool,
     ) -> hir::Path;
 
-    /// Obtain the resolution for a `NodeId`.
-    fn get_resolution(&mut self, id: NodeId) -> Option<PathResolution>;
+    /// Obtain resolution for a `NodeId` with a single resolution.
+    fn get_partial_res(&mut self, id: NodeId) -> Option<PartialRes>;
 
-    /// Obtain the possible resolutions for the given `use` statement.
-    fn get_import(&mut self, id: NodeId) -> PerNS<Option<PathResolution>>;
+    /// Obtain per-namespace resolutions for `use` statement with the given `NoedId`.
+    fn get_import_res(&mut self, id: NodeId) -> PerNS<Option<Res<NodeId>>>;
+
+    /// Obtain resolution for a label with the given `NodeId`.
+    fn get_label_res(&mut self, id: NodeId) -> Option<NodeId>;
 
     /// We must keep the set of definitions up to date as we add nodes that weren't in the AST.
     /// This should only return `None` during testing.
@@ -821,7 +824,7 @@ fn lower_res(&mut self, res: Res<NodeId>) -> Res {
     }
 
     fn expect_full_res(&mut self, id: NodeId) -> Res<NodeId> {
-        self.resolver.get_resolution(id).map_or(Res::Err, |pr| {
+        self.resolver.get_partial_res(id).map_or(Res::Err, |pr| {
             if pr.unresolved_segments() != 0 {
                 bug!("path not fully resolved: {:?}", pr);
             }
@@ -830,12 +833,7 @@ fn expect_full_res(&mut self, id: NodeId) -> Res<NodeId> {
     }
 
     fn expect_full_res_from_use(&mut self, id: NodeId) -> impl Iterator<Item = Res<NodeId>> {
-        self.resolver.get_import(id).present_items().map(|pr| {
-            if pr.unresolved_segments() != 0 {
-                bug!("path not fully resolved: {:?}", pr);
-            }
-            pr.base_res()
-        })
+        self.resolver.get_import_res(id).present_items()
     }
 
     fn diagnostic(&self) -> &errors::Handler {
@@ -1251,7 +1249,7 @@ fn lower_label(&mut self, label: Option<Label>) -> Option<hir::Label> {
     fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
         let target_id = match destination {
             Some((id, _)) => {
-                if let Res::Label(loop_id) = self.expect_full_res(id) {
+                if let Some(loop_id) = self.resolver.get_label_res(id) {
                     Ok(self.lower_node_id(loop_id))
                 } else {
                     Err(hir::LoopIdError::UnresolvedLabel)
@@ -1842,13 +1840,13 @@ fn lower_qpath(
         let qself_position = qself.as_ref().map(|q| q.position);
         let qself = qself.as_ref().map(|q| self.lower_ty(&q.ty, itctx.reborrow()));
 
-        let resolution = self.resolver
-            .get_resolution(id)
-            .unwrap_or_else(|| PathResolution::new(Res::Err));
+        let partial_res = self.resolver
+            .get_partial_res(id)
+            .unwrap_or_else(|| PartialRes::new(Res::Err));
 
-        let proj_start = p.segments.len() - resolution.unresolved_segments();
+        let proj_start = p.segments.len() - partial_res.unresolved_segments();
         let path = P(hir::Path {
-            res: self.lower_res(resolution.base_res()),
+            res: self.lower_res(partial_res.base_res()),
             segments: p.segments[..proj_start]
                 .iter()
                 .enumerate()
@@ -1869,7 +1867,7 @@ fn lower_qpath(
                         krate: def_id.krate,
                         index: this.def_key(def_id).parent.expect("missing parent"),
                     };
-                    let type_def_id = match resolution.base_res() {
+                    let type_def_id = match partial_res.base_res() {
                         Res::Def(DefKind::AssociatedTy, def_id) if i + 2 == proj_start => {
                             Some(parent_def_id(self, def_id))
                         }
@@ -1886,7 +1884,7 @@ fn lower_qpath(
                         }
                         _ => None,
                     };
-                    let parenthesized_generic_args = match resolution.base_res() {
+                    let parenthesized_generic_args = match partial_res.base_res() {
                         // `a::b::Trait(Args)`
                         Res::Def(DefKind::Trait, _)
                             if i + 1 == proj_start => ParenthesizedGenericArgs::Ok,
@@ -1940,7 +1938,7 @@ fn lower_qpath(
 
         // Simple case, either no projections, or only fully-qualified.
         // E.g., `std::mem::size_of` or `<I as Iterator>::Item`.
-        if resolution.unresolved_segments() == 0 {
+        if partial_res.unresolved_segments() == 0 {
             return hir::QPath::Resolved(qself, path);
         }
 
@@ -2792,7 +2790,7 @@ fn lower_generics(
                                     && bound_pred.bound_generic_params.is_empty() =>
                             {
                                 if let Some(Res::Def(DefKind::TyParam, def_id)) = self.resolver
-                                    .get_resolution(bound_pred.bounded_ty.id)
+                                    .get_partial_res(bound_pred.bounded_ty.id)
                                     .map(|d| d.base_res())
                                 {
                                     if let Some(node_id) =
@@ -3946,7 +3944,7 @@ fn lower_pat(&mut self, p: &Pat) -> P<hir::Pat> {
         let node = match p.node {
             PatKind::Wild => hir::PatKind::Wild,
             PatKind::Ident(ref binding_mode, ident, ref sub) => {
-                match self.resolver.get_resolution(p.id).map(|d| d.base_res()) {
+                match self.resolver.get_partial_res(p.id).map(|d| d.base_res()) {
                     // `None` can occur in body-less function signatures
                     res @ None | res @ Some(Res::Local(_)) => {
                         let canonical_id = match res {

src/librustc/hir/mod.rs

@@ -2143,7 +2143,7 @@ pub enum UseKind {
 /// resolve maps each TraitRef's ref_id to its defining trait; that's all
 /// that the ref_id is for. Note that ref_id's value is not the NodeId of the
 /// trait being referred to but just a unique NodeId that serves as a key
-/// within the ResMap.
+/// within the resolution map.
 #[derive(Clone, RustcEncodable, RustcDecodable, Debug, HashStable)]
 pub struct TraitRef {
     pub path: Path,

src/librustc_mir/hair/pattern/check_match.rs

@@ -286,7 +286,7 @@ fn check_irrefutable(&self, pat: &'tcx Pat, origin: &str) {
                 PatKind::Path(hir::QPath::Resolved(None, ref path))
                         if path.segments.len() == 1 && path.segments[0].args.is_none() => {
                     format!("interpreted as {} {} pattern, not new variable",
-                            path.res.article(), path.res.kind_name())
+                            path.res.article(), path.res.descr())
                 }
                 _ => format!("pattern `{}` not covered", pattern_string),
             };

src/librustc_resolve/diagnostics.rs

@@ -41,7 +41,7 @@ pub(crate) fn smart_resolve_report_errors(
         let item_str = path.last().unwrap().ident;
         let code = source.error_code(res.is_some());
         let (base_msg, fallback_label, base_span) = if let Some(res) = res {
-            (format!("expected {}, found {} `{}`", expected, res.kind_name(), path_str),
+            (format!("expected {}, found {} `{}`", expected, res.descr(), path_str),
                 format!("not a {}", expected),
                 span)
         } else {

src/librustc_resolve/macros.rs

@@ -333,7 +333,7 @@ fn resolve_macro_to_res(
                     // Not only attributes, but anything in macro namespace can result in
                     // `Res::NonMacroAttr` definition (e.g., `inline!()`), so we must report
                     // an error for those cases.
-                    let msg = format!("expected a macro, found {}", res.kind_name());
+                    let msg = format!("expected a macro, found {}", res.descr());
                     self.session.span_err(path.span, &msg);
                     return Err(Determinacy::Determined);
                 }
@@ -913,7 +913,7 @@ pub fn finalize_current_module_macro_resolutions(&mut self) {
                         // (which is a best effort error recovery tool, basically), so we can't
                         // promise their resolution won't change later.
                         let msg = format!("inconsistent resolution for a macro: first {}, then {}",
-                                          initial_res.kind_name(), res.kind_name());
+                                          initial_res.descr(), res.descr());
                         this.session.span_err(span, &msg);
                     } else {
                         span_bug!(span, "inconsistent resolution for a macro");

src/librustc_resolve/resolve_imports.rs

@@ -21,7 +21,7 @@
     UNUSED_IMPORTS,
 };
 use rustc::hir::def_id::{CrateNum, DefId};
-use rustc::hir::def::{self, DefKind, PathResolution, Export};
+use rustc::hir::def::{self, DefKind, PartialRes, Export};
 use rustc::session::DiagnosticMessageId;
 use rustc::util::nodemap::FxHashSet;
 use rustc::{bug, span_bug};
@@ -1233,8 +1233,7 @@ fn finalize_import(
                     res = Res::Err;
                 }
             }
-            let import = this.import_map.entry(directive.id).or_default();
-            import[ns] = Some(PathResolution::new(res));
+            this.import_res_map.entry(directive.id).or_default()[ns] = Some(res);
         });
 
         self.check_for_redundant_imports(
@@ -1371,7 +1370,7 @@ fn resolve_glob_import(&mut self, directive: &'b ImportDirective<'b>) {
         }
 
         // Record the destination of this import
-        self.record_res(directive.id, PathResolution::new(module.res().unwrap()));
+        self.record_partial_res(directive.id, PartialRes::new(module.res().unwrap()));
     }
 
     // Miscellaneous post-processing, including recording re-exports,

src/librustc_save_analysis/lib.rs

@@ -796,7 +796,6 @@ fn fn_type(seg: &ast::PathSegment) -> bool {
             }
             Res::PrimTy(..) |
             Res::SelfTy(..) |
-            Res::Label(..) |
             Res::Def(HirDefKind::Macro(..), _) |
             Res::ToolMod |
             Res::NonMacroAttr(..) |

src/librustc_save_analysis/sig.rs

@@ -579,7 +579,7 @@ fn make(&self, offset: usize, id: Option<NodeId>, scx: &SaveContext<'_, '_>) ->
         let res = scx.get_path_res(id.ok_or("Missing id for Path")?);
 
         let (name, start, end) = match res {
-            Res::Label(..) | Res::PrimTy(..) | Res::SelfTy(..) | Res::Err => {
+            Res::PrimTy(..) | Res::SelfTy(..) | Res::Err => {
                 return Ok(Signature {
                     text: pprust::path_to_string(self),
                     defs: vec![],

src/librustc_typeck/check/_match.rs

@@ -884,7 +884,7 @@ fn check_pat_tuple_struct(
         };
         let report_unexpected_res = |res: Res| {
             let msg = format!("expected tuple struct/variant, found {} `{}`",
-                              res.kind_name(),
+                              res.descr(),
                               hir::print::to_string(tcx.hir(), |s| s.print_qpath(qpath, false)));
             struct_span_err!(tcx.sess, pat.span, E0164, "{}", msg)
                 .span_label(pat.span, "not a tuple variant or struct").emit();
@@ -947,7 +947,7 @@ fn check_pat_tuple_struct(
             let fields_ending = if variant.fields.len() == 1 { "" } else { "s" };
             struct_span_err!(tcx.sess, pat.span, E0023,
                              "this pattern has {} field{}, but the corresponding {} has {} field{}",
-                             subpats.len(), subpats_ending, res.kind_name(),
+                             subpats.len(), subpats_ending, res.descr(),
                              variant.fields.len(),  fields_ending)
                 .span_label(pat.span, format!("expected {} field{}, found {}",
                                               variant.fields.len(), fields_ending, subpats.len()))

src/librustc_typeck/check/mod.rs

@@ -1902,7 +1902,7 @@ fn report_unexpected_variant_res<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
                                                  qpath: &QPath) {
     span_err!(tcx.sess, span, E0533,
               "expected unit struct/variant or constant, found {} `{}`",
-              res.kind_name(),
+              res.descr(),
               hir::print::to_string(tcx.hir(), |s| s.print_qpath(qpath, false)));
 }
 

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -513,18 +513,18 @@ fn ambiguity_error(
             msg += &format!(
                 "both {} {} and {} {}",
                 first_def.article(),
-                first_def.kind_name(),
+                first_def.descr(),
                 second_def.article(),
-                second_def.kind_name(),
+                second_def.descr(),
             );
         }
         _ => {
             let mut candidates = candidates.iter().peekable();
             while let Some((res, _)) = candidates.next() {
                 if candidates.peek().is_some() {
-                    msg += &format!("{} {}, ", res.article(), res.kind_name());
+                    msg += &format!("{} {}, ", res.article(), res.descr());
                 } else {
-                    msg += &format!("and {} {}", res.article(), res.kind_name());
+                    msg += &format!("and {} {}", res.article(), res.descr());
                 }
             }
         }
@@ -575,7 +575,7 @@ fn ambiguity_error(
 
                 diag.span_suggestion(
                     sp,
-                    &format!("to link to the {}, {}", res.kind_name(), action),
+                    &format!("to link to the {}, {}", res.descr(), action),
                     suggestion,
                     Applicability::MaybeIncorrect,
                 );