Auto merge of #67742 - mark-i-m:describe-it, r=matthewjasper

Generalized article_and_description

r? @matthewjasper

The logic of finding the right word and article to print seems to be repeated elsewhere... this is an experimental method to unify this logic...

src/librustc/query/mod.rs

@@ -308,6 +308,9 @@ rustc_queries! {
         /// Returns `Some(mutability)` if the node pointed to by `def_id` is a static item.
         query static_mutability(_: DefId) -> Option<hir::Mutability> {}
 
+        /// Returns `Some(generator_kind)` if the node pointed to by `def_id` is a generator.
+        query generator_kind(_: DefId) -> Option<hir::GeneratorKind> {}
+
         /// Gets a map with the variance of every item; use `item_variance` instead.
         query crate_variances(_: CrateNum) -> &'tcx ty::CrateVariancesMap<'tcx> {
             desc { "computing the variances for items in this crate" }

src/librustc/ty/context.rs

@@ -5,7 +5,7 @@ use crate::dep_graph::DepGraph;
 use crate::dep_graph::{self, DepConstructor};
 use crate::hir::exports::Export;
 use crate::hir::map as hir_map;
-use crate::hir::map::DefPathHash;
+use crate::hir::map::{DefPathData, DefPathHash};
 use crate::ich::{NodeIdHashingMode, StableHashingContext};
 use crate::infer::canonical::{Canonical, CanonicalVarInfo, CanonicalVarInfos};
 use crate::lint::{struct_lint_level, LintSource};
@@ -209,7 +209,7 @@ fn validate_hir_id_for_typeck_tables(
             ty::tls::with(|tcx| {
                 bug!(
                     "node {} with HirId::owner {:?} cannot be placed in \
-                        TypeckTables with local_id_root {:?}",
+                     TypeckTables with local_id_root {:?}",
                     tcx.hir().node_to_string(hir_id),
                     DefId::local(hir_id.owner),
                     local_id_root
@@ -1512,6 +1512,24 @@ impl<'tcx> TyCtxt<'tcx> {
                 .subst(*self, self.mk_substs([self.lifetimes.re_static.into()].iter())),
         )
     }
+
+    /// Returns a displayable description and article for the given `def_id` (e.g. `("a", "struct")`).
+    pub fn article_and_description(&self, def_id: DefId) -> (&'static str, &'static str) {
+        match self.def_key(def_id).disambiguated_data.data {
+            DefPathData::TypeNs(..) | DefPathData::ValueNs(..) | DefPathData::MacroNs(..) => {
+                let kind = self.def_kind(def_id).unwrap();
+                (kind.article(), kind.descr(def_id))
+            }
+            DefPathData::ClosureExpr => match self.generator_kind(def_id) {
+                None => ("a", "closure"),
+                Some(rustc_hir::GeneratorKind::Async(..)) => ("an", "async closure"),
+                Some(rustc_hir::GeneratorKind::Gen) => ("a", "generator"),
+            },
+            DefPathData::LifetimeNs(..) => ("a", "lifetime"),
+            DefPathData::Impl => ("an", "implementation"),
+            _ => bug!("article_and_description called on def_id {:?}", def_id),
+        }
+    }
 }
 
 impl<'tcx> GlobalCtxt<'tcx> {

src/librustc_metadata/rmeta/decoder.rs

@@ -492,7 +492,7 @@ impl MetadataBlob {
     }
 }
 
-impl<'tcx> EntryKind<'tcx> {
+impl EntryKind {
     fn def_kind(&self) -> Option<DefKind> {
         Some(match *self {
             EntryKind::Const(..) => DefKind::Const,
@@ -606,11 +606,11 @@ impl<'a, 'tcx> CrateMetadata {
         self.root.proc_macro_data.and_then(|data| data.decode(self).find(|x| *x == id)).is_some()
     }
 
-    fn maybe_kind(&self, item_id: DefIndex) -> Option<EntryKind<'tcx>> {
+    fn maybe_kind(&self, item_id: DefIndex) -> Option<EntryKind> {
         self.root.per_def.kind.get(self, item_id).map(|k| k.decode(self))
     }
 
-    fn kind(&self, item_id: DefIndex) -> EntryKind<'tcx> {
+    fn kind(&self, item_id: DefIndex) -> EntryKind {
         assert!(!self.is_proc_macro(item_id));
         self.maybe_kind(item_id).unwrap_or_else(|| {
             bug!(
@@ -715,7 +715,7 @@ impl<'a, 'tcx> CrateMetadata {
     fn get_variant(
         &self,
         tcx: TyCtxt<'tcx>,
-        kind: &EntryKind<'_>,
+        kind: &EntryKind,
         index: DefIndex,
         parent_did: DefId,
     ) -> ty::VariantDef {
@@ -1382,6 +1382,13 @@ impl<'a, 'tcx> CrateMetadata {
         }
     }
 
+    fn generator_kind(&self, id: DefIndex) -> Option<hir::GeneratorKind> {
+        match self.kind(id) {
+            EntryKind::Generator(data) => Some(data),
+            _ => None,
+        }
+    }
+
     fn fn_sig(&self, id: DefIndex, tcx: TyCtxt<'tcx>) -> ty::PolyFnSig<'tcx> {
         self.root.per_def.fn_sig.get(self, id).unwrap().decode((self, tcx))
     }
@@ -1491,8 +1498,8 @@ impl<'a, 'tcx> CrateMetadata {
                     );
                     debug!(
                         "CrateMetaData::imported_source_files alloc \
-                        source_file {:?} original (start_pos {:?} end_pos {:?}) \
-                        translated (start_pos {:?} end_pos {:?})",
+                         source_file {:?} original (start_pos {:?} end_pos {:?}) \
+                         translated (start_pos {:?} end_pos {:?})",
                         local_version.name,
                         start_pos,
                         end_pos,

src/librustc_metadata/rmeta/decoder/cstore_impl.rs

@@ -134,6 +134,7 @@ provide! { <'tcx> tcx, def_id, other, cdata,
     asyncness => { cdata.asyncness(def_id.index) }
     is_foreign_item => { cdata.is_foreign_item(def_id.index) }
     static_mutability => { cdata.static_mutability(def_id.index) }
+    generator_kind => { cdata.generator_kind(def_id.index) }
     def_kind => { cdata.def_kind(def_id.index) }
     def_span => { cdata.get_span(def_id.index, &tcx.sess) }
     lookup_stability => {

src/librustc_metadata/rmeta/encoder.rs

@@ -306,7 +306,7 @@ impl<'tcx> EncodeContext<'tcx> {
                 assert!(
                     last_min_end <= lazy.position,
                     "make sure that the calls to `lazy*` \
-                    are in the same order as the metadata fields",
+                     are in the same order as the metadata fields",
                 );
                 lazy.position.get() - last_min_end.get()
             }
@@ -1248,12 +1248,7 @@ impl EncodeContext<'tcx> {
         self.encode_deprecation(def_id);
     }
 
-    fn encode_info_for_generic_param(
-        &mut self,
-        def_id: DefId,
-        kind: EntryKind<'tcx>,
-        encode_type: bool,
-    ) {
+    fn encode_info_for_generic_param(&mut self, def_id: DefId, kind: EntryKind, encode_type: bool) {
         record!(self.per_def.kind[def_id] <- kind);
         record!(self.per_def.visibility[def_id] <- ty::Visibility::Public);
         record!(self.per_def.span[def_id] <- self.tcx.def_span(def_id));
@@ -1271,12 +1266,9 @@ impl EncodeContext<'tcx> {
         let ty = self.tcx.typeck_tables_of(def_id).node_type(hir_id);
 
         record!(self.per_def.kind[def_id] <- match ty.kind {
-            ty::Generator(def_id, ..) => {
-                let layout = self.tcx.generator_layout(def_id);
-                let data = GeneratorData {
-                    layout: layout.clone(),
-                };
-                EntryKind::Generator(self.lazy(data))
+            ty::Generator(..) => {
+                let data = self.tcx.generator_kind(def_id).unwrap();
+                EntryKind::Generator(data)
             }
 
             ty::Closure(..) => EntryKind::Closure,

src/librustc_metadata/rmeta/mod.rs

@@ -252,7 +252,7 @@ macro_rules! define_per_def_tables {
 }
 
 define_per_def_tables! {
-    kind: Table<DefIndex, Lazy!(EntryKind<'tcx>)>,
+    kind: Table<DefIndex, Lazy<EntryKind>>,
     visibility: Table<DefIndex, Lazy<ty::Visibility>>,
     span: Table<DefIndex, Lazy<Span>>,
     attributes: Table<DefIndex, Lazy<[ast::Attribute]>>,
@@ -279,7 +279,7 @@ define_per_def_tables! {
 }
 
 #[derive(Copy, Clone, RustcEncodable, RustcDecodable)]
-enum EntryKind<'tcx> {
+enum EntryKind {
     Const(mir::ConstQualifs, Lazy<RenderedConst>),
     ImmStatic,
     MutStatic,
@@ -302,7 +302,7 @@ enum EntryKind<'tcx> {
     Mod(Lazy<ModData>),
     MacroDef(Lazy<MacroDef>),
     Closure,
-    Generator(Lazy!(GeneratorData<'tcx>)),
+    Generator(hir::GeneratorKind),
     Trait(Lazy<TraitData>),
     Impl(Lazy<ImplData>),
     Method(Lazy<MethodData>),

src/librustc_mir/borrow_check/diagnostics/conflict_errors.rs

@@ -1257,7 +1257,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
             }
             _ => bug!(
                 "report_escaping_closure_capture called with unexpected constraint \
-                       category: `{:?}`",
+                 category: `{:?}`",
                 category
             ),
         };
@@ -1275,17 +1275,7 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
     ) -> DiagnosticBuilder<'cx> {
         let tcx = self.infcx.tcx;
 
-        let escapes_from = if tcx.is_closure(self.mir_def_id) {
-            let tables = tcx.typeck_tables_of(self.mir_def_id);
-            let mir_hir_id = tcx.hir().def_index_to_hir_id(self.mir_def_id.index);
-            match tables.node_type(mir_hir_id).kind {
-                ty::Closure(..) => "closure",
-                ty::Generator(..) => "generator",
-                _ => bug!("Closure body doesn't have a closure or generator type"),
-            }
-        } else {
-            "function"
-        };
+        let (_, escapes_from) = tcx.article_and_description(self.mir_def_id);
 
         let mut err =
             borrowck_errors::borrowed_data_escapes_closure(tcx, escape_span, escapes_from);

src/librustc_mir/borrow_check/diagnostics/region_errors.rs

@@ -427,18 +427,17 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
             errci.outlived_fr,
         );
 
-        let escapes_from = match self.regioncx.universal_regions().defining_ty {
-            DefiningTy::Closure(..) => "closure",
-            DefiningTy::Generator(..) => "generator",
-            DefiningTy::FnDef(..) => "function",
-            DefiningTy::Const(..) => "const",
-        };
+        let (_, escapes_from) = self
+            .infcx
+            .tcx
+            .article_and_description(self.regioncx.universal_regions().defining_ty.def_id());
 
         // Revert to the normal error in these cases.
         // Assignments aren't "escapes" in function items.
         if (fr_name_and_span.is_none() && outlived_fr_name_and_span.is_none())
-            || (*category == ConstraintCategory::Assignment && escapes_from == "function")
-            || escapes_from == "const"
+            || (*category == ConstraintCategory::Assignment
+                && self.regioncx.universal_regions().defining_ty.is_fn_def())
+            || self.regioncx.universal_regions().defining_ty.is_const()
         {
             return self.report_general_error(&ErrorConstraintInfo {
                 fr_is_local: true,
@@ -504,8 +503,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         let mut diag =
             self.infcx.tcx.sess.struct_span_err(*span, "lifetime may not live long enough");
 
-        let mir_def_name =
-            if self.infcx.tcx.is_closure(self.mir_def_id) { "closure" } else { "function" };
+        let (_, mir_def_name) = self.infcx.tcx.article_and_description(self.mir_def_id);
 
         let fr_name = self.give_region_a_name(*fr).unwrap();
         fr_name.highlight_region_name(&mut diag);

src/librustc_mir/borrow_check/universal_regions.rs

@@ -131,6 +131,29 @@ impl<'tcx> DefiningTy<'tcx> {
             DefiningTy::FnDef(..) | DefiningTy::Const(..) => 0,
         }
     }
+
+    pub fn is_fn_def(&self) -> bool {
+        match *self {
+            DefiningTy::FnDef(..) => true,
+            _ => false,
+        }
+    }
+
+    pub fn is_const(&self) -> bool {
+        match *self {
+            DefiningTy::Const(..) => true,
+            _ => false,
+        }
+    }
+
+    pub fn def_id(&self) -> DefId {
+        match *self {
+            DefiningTy::Closure(def_id, ..)
+            | DefiningTy::Generator(def_id, ..)
+            | DefiningTy::FnDef(def_id, ..)
+            | DefiningTy::Const(def_id, ..) => def_id,
+        }
+    }
 }
 
 #[derive(Debug)]

src/librustc_typeck/collect.rs

@@ -76,6 +76,7 @@ pub fn provide(providers: &mut Providers<'_>) {
         impl_polarity,
         is_foreign_item,
         static_mutability,
+        generator_kind,
         codegen_fn_attrs,
         collect_mod_item_types,
         ..*providers
@@ -1006,7 +1007,7 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TraitDef {
             .struct_span_err(
                 item.span,
                 "the `#[rustc_paren_sugar]` attribute is a temporary means of controlling \
-             which traits can use parenthetical notation",
+                 which traits can use parenthetical notation",
             )
             .help("add `#![feature(unboxed_closures)]` to the crate attributes to use it")
             .emit();
@@ -2106,7 +2107,7 @@ fn compute_sig_of_foreign_fn_decl<'tcx>(
                         ast_ty.span,
                         &format!(
                             "use of SIMD type `{}` in FFI is highly experimental and \
-                            may result in invalid code",
+                             may result in invalid code",
                             tcx.hir().hir_to_pretty_string(ast_ty.hir_id)
                         ),
                     )
@@ -2145,6 +2146,17 @@ fn static_mutability(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::Mutability>
     }
 }
 
+fn generator_kind(tcx: TyCtxt<'_>, def_id: DefId) -> Option<hir::GeneratorKind> {
+    match tcx.hir().get_if_local(def_id) {
+        Some(Node::Expr(&rustc_hir::Expr {
+            kind: rustc_hir::ExprKind::Closure(_, _, body_id, _, _),
+            ..
+        })) => tcx.hir().body(body_id).generator_kind(),
+        Some(_) => None,
+        _ => bug!("generator_kind applied to non-local def-id {:?}", def_id),
+    }
+}
+
 fn from_target_feature(
     tcx: TyCtxt<'_>,
     id: DefId,

src/test/ui/async-await/issues/issue-62097.nll.stderr

@@ -16,13 +16,13 @@ help: to force the closure to take ownership of `self` (and any other referenced
 LL |         foo(move || self.bar()).await;
    |             ^^^^^^^
 
-error[E0521]: borrowed data escapes outside of function
+error[E0521]: borrowed data escapes outside of method
   --> $DIR/issue-62097.rs:13:9
    |
 LL |     pub async fn run_dummy_fn(&self) {
-   |                               ----- `self` is a reference that is only valid in the function body
+   |                               ----- `self` is a reference that is only valid in the method body
 LL |         foo(|| self.bar()).await;
-   |         ^^^^^^^^^^^^^^^^^^ `self` escapes the function body here
+   |         ^^^^^^^^^^^^^^^^^^ `self` escapes the method body here
 
 error: aborting due to 2 previous errors
 

src/test/ui/async-await/issues/issue-63388-1.nll.stderr

@@ -9,7 +9,7 @@ LL |       ) -> &dyn Foo
 LL | /     {
 LL | |         foo
 LL | |     }
-   | |_____^ function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'1`
+   | |_____^ method was supposed to return data with lifetime `'a` but it is returning data with lifetime `'1`
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-16683.nll.stderr

@@ -1,10 +1,10 @@
-error[E0521]: borrowed data escapes outside of function
+error[E0521]: borrowed data escapes outside of method
   --> $DIR/issue-16683.rs:4:9
    |
 LL |     fn b(&self) {
-   |          ----- `self` is a reference that is only valid in the function body
+   |          ----- `self` is a reference that is only valid in the method body
 LL |         self.a();
-   |         ^^^^^^^^ `self` escapes the function body here
+   |         ^^^^^^^^ `self` escapes the method body here
 
 error: aborting due to previous error
 

src/test/ui/issues/issue-17758.nll.stderr

@@ -1,10 +1,10 @@
-error[E0521]: borrowed data escapes outside of function
+error[E0521]: borrowed data escapes outside of method
   --> $DIR/issue-17758.rs:7:9
    |
 LL |     fn bar(&self) {
-   |            ----- `self` is a reference that is only valid in the function body
+   |            ----- `self` is a reference that is only valid in the method body
 LL |         self.foo();
-   |         ^^^^^^^^^^ `self` escapes the function body here
+   |         ^^^^^^^^^^ `self` escapes the method body here
 
 error: aborting due to previous error
 

src/test/ui/lifetimes/lifetime-errors/ex1-return-one-existing-name-if-else-using-impl.nll.stderr

@@ -7,7 +7,7 @@ LL |     fn foo<'a>(x: &i32, y: &'a i32) -> &'a i32 {
    |            lifetime `'a` defined here
 LL | 
 LL |         if x > y { x } else { y }
-   |                    ^ function was supposed to return data with lifetime `'a` but it is returning data with lifetime `'1`
+   |                    ^ method was supposed to return data with lifetime `'a` but it is returning data with lifetime `'1`
 
 error: aborting due to previous error
 

src/test/ui/lifetimes/lifetime-errors/ex1-return-one-existing-name-return-type-is-anon.nll.stderr

@@ -7,7 +7,7 @@ LL |   fn foo<'a>(&self, x: &'a i32) -> &i32 {
    |          lifetime `'a` defined here
 LL | 
 LL |     x
-   |     ^ function was supposed to return data with lifetime `'1` but it is returning data with lifetime `'a`
+   |     ^ method was supposed to return data with lifetime `'1` but it is returning data with lifetime `'a`
 
 error: aborting due to previous error