Rollup merge of #139662 - nnethercote:tweak-DefPathData, r=compiler-errors

Tweak `DefPathData`

Some improvements in and around `DefPathData`, following on from #137977.

r? `@spastorino`

compiler/rustc_hir/src/def.rs

@@ -267,11 +267,16 @@ impl DefKind {
             | DefKind::ForeignTy
             | DefKind::TraitAlias
             | DefKind::TyParam
-            | DefKind::ExternCrate => DefPathData::TypeNs(Some(name.unwrap())),
+            | DefKind::ExternCrate => DefPathData::TypeNs(name.unwrap()),
 
-            // An associated type names will be missing for an RPITIT. It will
+            // An associated type name will be missing for an RPITIT.
-            // later be given a name with `synthetic` in it, if necessary.
+            DefKind::AssocTy => {
-            DefKind::AssocTy => DefPathData::TypeNs(name),
+                if let Some(name) = name {
+                    DefPathData::TypeNs(name)
+                } else {
+                    DefPathData::AnonAssocTy
+                }
+            }
 
             // It's not exactly an anon const, but wrt DefPathData, there
             // is no difference.

compiler/rustc_hir/src/definitions.rs

@@ -271,9 +271,8 @@ pub enum DefPathData {
     Use,
     /// A global asm item.
     GlobalAsm,
-    /// Something in the type namespace. Will be empty for RPITIT associated
+    /// Something in the type namespace.
-    /// types, which are given a synthetic name later, if necessary.
+    TypeNs(Symbol),
-    TypeNs(Option<Symbol>),
     /// Something in the value namespace.
     ValueNs(Symbol),
     /// Something in the macro namespace.
@@ -291,6 +290,8 @@ pub enum DefPathData {
     /// An existential `impl Trait` type node.
     /// Argument position `impl Trait` have a `TypeNs` with their pretty-printed name.
     OpaqueTy,
+    /// An anonymous associated type from an RPITIT.
+    AnonAssocTy,
     /// A synthetic body for a coroutine's by-move body.
     SyntheticCoroutineBody,
 }
@@ -413,9 +414,7 @@ impl DefPathData {
     pub fn get_opt_name(&self) -> Option<Symbol> {
         use self::DefPathData::*;
         match *self {
-            TypeNs(name) => name,
+            TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
-
-            ValueNs(name) | MacroNs(name) | LifetimeNs(name) => Some(name),
 
             Impl
             | ForeignMod
@@ -426,6 +425,7 @@ impl DefPathData {
             | Ctor
             | AnonConst
             | OpaqueTy
+            | AnonAssocTy
             | SyntheticCoroutineBody => None,
         }
     }
@@ -433,14 +433,9 @@ impl DefPathData {
     pub fn name(&self) -> DefPathDataName {
         use self::DefPathData::*;
         match *self {
-            TypeNs(name) => {
+            TypeNs(name) | ValueNs(name) | MacroNs(name) | LifetimeNs(name) => {
-                if let Some(name) = name {
                 DefPathDataName::Named(name)
-                } else {
-                    DefPathDataName::Anon { namespace: sym::synthetic }
             }
-            }
-            ValueNs(name) | MacroNs(name) | LifetimeNs(name) => DefPathDataName::Named(name),
             // Note that this does not show up in user print-outs.
             CrateRoot => DefPathDataName::Anon { namespace: kw::Crate },
             Impl => DefPathDataName::Anon { namespace: kw::Impl },
@@ -451,6 +446,7 @@ impl DefPathData {
             Ctor => DefPathDataName::Anon { namespace: sym::constructor },
             AnonConst => DefPathDataName::Anon { namespace: sym::constant },
             OpaqueTy => DefPathDataName::Anon { namespace: sym::opaque },
+            AnonAssocTy => DefPathDataName::Anon { namespace: sym::anon_assoc },
             SyntheticCoroutineBody => DefPathDataName::Anon { namespace: sym::synthetic },
         }
     }

compiler/rustc_middle/src/ty/print/pretty.rs

@@ -620,7 +620,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             // the children of the visible parent (as was done when computing
             // `visible_parent_map`), looking for the specific child we currently have and then
             // have access to the re-exported name.
-            DefPathData::TypeNs(Some(ref mut name)) if Some(visible_parent) != actual_parent => {
+            DefPathData::TypeNs(ref mut name) if Some(visible_parent) != actual_parent => {
                 // Item might be re-exported several times, but filter for the one
                 // that's public and whose identifier isn't `_`.
                 let reexport = self
@@ -641,7 +641,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
             }
             // Re-exported `extern crate` (#43189).
             DefPathData::CrateRoot => {
-                data = DefPathData::TypeNs(Some(self.tcx().crate_name(def_id.krate)));
+                data = DefPathData::TypeNs(self.tcx().crate_name(def_id.krate));
             }
             _ => {}
         }

compiler/rustc_middle/src/ty/significant_drop_order.rs

@@ -26,7 +26,7 @@ fn true_significant_drop_ty<'tcx>(
                     name_rev.push(tcx.crate_name(did.krate));
                 }
                 rustc_hir::definitions::DefPathData::TypeNs(symbol) => {
-                    name_rev.push(symbol.unwrap());
+                    name_rev.push(symbol);
                 }
                 _ => return None,
             }

compiler/rustc_resolve/src/lib.rs

@@ -1337,12 +1337,12 @@ impl<'tcx> Resolver<'_, 'tcx> {
         expn_id: ExpnId,
         span: Span,
     ) -> TyCtxtFeed<'tcx, LocalDefId> {
-        let data = def_kind.def_path_data(name);
         assert!(
             !self.node_id_to_def_id.contains_key(&node_id),
-            "adding a def'n for node-id {:?} and data {:?} but a previous def'n exists: {:?}",
+            "adding a def for node-id {:?}, name {:?}, data {:?} but a previous def exists: {:?}",
             node_id,
-            data,
+            name,
+            def_kind,
             self.tcx.definitions_untracked().def_key(self.node_id_to_def_id[&node_id].key()),
         );
 

compiler/rustc_sanitizers/src/cfi/typeid/itanium_cxx_abi/encode.rs

@@ -721,7 +721,8 @@ fn encode_ty_name(tcx: TyCtxt<'_>, def_id: DefId) -> String {
             | hir::definitions::DefPathData::Use
             | hir::definitions::DefPathData::GlobalAsm
             | hir::definitions::DefPathData::MacroNs(..)
-            | hir::definitions::DefPathData::LifetimeNs(..) => {
+            | hir::definitions::DefPathData::LifetimeNs(..)
+            | hir::definitions::DefPathData::AnonAssocTy => {
                 bug!("encode_ty_name: unexpected `{:?}`", disambiguated_data.data);
             }
         });

compiler/rustc_span/src/symbol.rs

@@ -454,6 +454,7 @@ symbols! {
         and_then,
         anon,
         anon_adt,
+        anon_assoc,
         anonymous_lifetime_in_impl_trait,
         any,
         append_const_msg,

compiler/rustc_symbol_mangling/src/v0.rs

@@ -858,7 +858,8 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
             | DefPathData::GlobalAsm
             | DefPathData::Impl
             | DefPathData::MacroNs(_)
-            | DefPathData::LifetimeNs(_) => {
+            | DefPathData::LifetimeNs(_)
+            | DefPathData::AnonAssocTy => {
                 bug!("symbol_names: unexpected DefPathData: {:?}", disambiguated_data.data)
             }
         };

compiler/rustc_ty_utils/src/assoc.rs

@@ -252,7 +252,7 @@ fn associated_type_for_impl_trait_in_trait(
     assert_eq!(tcx.def_kind(trait_def_id), DefKind::Trait);
 
     let span = tcx.def_span(opaque_ty_def_id);
-    // No name because this is a synthetic associated type.
+    // No name because this is an anonymous associated type.
     let trait_assoc_ty = tcx.at(span).create_def(trait_def_id, None, DefKind::AssocTy);
 
     let local_def_id = trait_assoc_ty.def_id();
@@ -305,7 +305,7 @@ fn associated_type_for_impl_trait_in_impl(
         hir::FnRetTy::DefaultReturn(_) => tcx.def_span(impl_fn_def_id),
         hir::FnRetTy::Return(ty) => ty.span,
     };
-    // No name because this is a synthetic associated type.
+    // No name because this is an anonymous associated type.
     let impl_assoc_ty = tcx.at(span).create_def(impl_local_def_id, None, DefKind::AssocTy);
 
     let local_def_id = impl_assoc_ty.def_id();

src/tools/clippy/clippy_utils/src/lib.rs

@@ -3504,7 +3504,7 @@ fn maybe_get_relative_path(from: &DefPath, to: &DefPath, max_super: usize) -> St
                 // a::b::c  ::d::sym refers to
                 // e::f::sym:: ::
                 // result should be super::super::super::super::e::f
-                if let DefPathData::TypeNs(Some(s)) = l {
+                if let DefPathData::TypeNs(s) = l {
                     path.push(s.to_string());
                 }
                 if let DefPathData::TypeNs(_) = r {
@@ -3515,7 +3515,7 @@ fn maybe_get_relative_path(from: &DefPath, to: &DefPath, max_super: usize) -> St
             // a::b::sym:: ::    refers to
             // c::d::e  ::f::sym
             // when looking at `f`
-            Left(DefPathData::TypeNs(Some(sym))) => path.push(sym.to_string()),
+            Left(DefPathData::TypeNs(sym)) => path.push(sym.to_string()),
             // consider:
             // a::b::c  ::d::sym refers to
             // e::f::sym:: ::
@@ -3529,7 +3529,7 @@ fn maybe_get_relative_path(from: &DefPath, to: &DefPath, max_super: usize) -> St
         // `super` chain would be too long, just use the absolute path instead
         once(String::from("crate"))
             .chain(to.data.iter().filter_map(|el| {
-                if let DefPathData::TypeNs(Some(sym)) = el.data {
+                if let DefPathData::TypeNs(sym) = el.data {
                     Some(sym.to_string())
                 } else {
                     None

tests/ui-fulldeps/stable-mir/check_assoc_items.rs

@@ -51,7 +51,7 @@ fn test_assoc_items() -> ControlFlow<()> {
     check_items(
         &trait_assoc_item_defs,
         &[
-            "ATrait::{synthetic#0}",
+            "ATrait::{anon_assoc#0}",
             "ATrait::rpitit",
             "ATrait::Assoc",
             "ATrait::assoc_fn_no_self",
@@ -64,7 +64,7 @@ fn test_assoc_items() -> ControlFlow<()> {
     check_items(
         &impl_assoc_item_defs,
         &[
-            "<AStruct as ATrait>::{synthetic#0}",
+            "<AStruct as ATrait>::{anon_assoc#0}",
             "<AStruct as ATrait>::rpitit",
             "<AStruct as ATrait>::Assoc",
             "<AStruct as ATrait>::assoc_fn_no_self",

tests/ui/delegation/unsupported.stderr

@@ -1,4 +1,4 @@
-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`
+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{anon_assoc#0}`
   --> $DIR/unsupported.rs:22:25
    |
 LL |         reuse to_reuse::opaque_ret;
@@ -9,7 +9,7 @@ note: ...which requires comparing an impl and trait method signature, inferring
    |
 LL |         reuse to_reuse::opaque_ret;
    |                         ^^^^^^^^^^
-   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{synthetic#0}`, completing the cycle
+   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>::{anon_assoc#0}`, completing the cycle
 note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:21:5: 21:24>` is well-formed
   --> $DIR/unsupported.rs:21:5
    |
@@ -17,7 +17,7 @@ LL |     impl ToReuse for u8 {
    |     ^^^^^^^^^^^^^^^^^^^
    = note: see https://rustc-dev-guide.rust-lang.org/overview.html#queries and https://rustc-dev-guide.rust-lang.org/query.html for more information
 
-error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`
+error[E0391]: cycle detected when computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{anon_assoc#0}`
   --> $DIR/unsupported.rs:25:24
    |
 LL |         reuse ToReuse::opaque_ret;
@@ -28,7 +28,7 @@ note: ...which requires comparing an impl and trait method signature, inferring
    |
 LL |         reuse ToReuse::opaque_ret;
    |                        ^^^^^^^^^^
-   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{synthetic#0}`, completing the cycle
+   = note: ...which again requires computing type of `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>::{anon_assoc#0}`, completing the cycle
 note: cycle used when checking that `opaque::<impl at $DIR/unsupported.rs:24:5: 24:25>` is well-formed
   --> $DIR/unsupported.rs:24:5
    |

tests/ui/impl-trait/in-trait/doesnt-satisfy.stderr

@@ -6,11 +6,11 @@ LL |     fn bar() -> () {}
    |
    = help: the trait `std::fmt::Display` is not implemented for `()`
    = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
-note: required by a bound in `Foo::{synthetic#0}`
+note: required by a bound in `Foo::{anon_assoc#0}`
   --> $DIR/doesnt-satisfy.rs:2:22
    |
 LL |     fn bar() -> impl std::fmt::Display;
-   |                      ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{synthetic#0}`
+   |                      ^^^^^^^^^^^^^^^^^ required by this bound in `Foo::{anon_assoc#0}`
 
 error: aborting due to 1 previous error
 

tests/ui/impl-trait/in-trait/dump.rs

@@ -8,7 +8,7 @@ trait Foo {
 }
 
 fn hello<'s, T: Foo>(x: &'s T) -> impl Sized + use<'s, T> {
-//~^ ERROR <T as Foo>::{synthetic#0}<'s/#1>
+//~^ ERROR <T as Foo>::{anon_assoc#0}<'s/#1>
     x.hello()
 }
 

tests/ui/impl-trait/in-trait/dump.stderr

@@ -1,4 +1,4 @@
-error: <T as Foo>::{synthetic#0}<'s/#1>
+error: <T as Foo>::{anon_assoc#0}<'s/#1>
   --> $DIR/dump.rs:10:35
    |
 LL | fn hello<'s, T: Foo>(x: &'s T) -> impl Sized + use<'s, T> {

tests/ui/impl-trait/in-trait/return-dont-satisfy-bounds.stderr

@@ -14,11 +14,11 @@ LL |     fn foo<F2: Foo<u8>>(self) -> impl Foo<u8> {
    |                                  ^^^^^^^^^^^^ the trait `Foo<char>` is not implemented for `impl Foo<u8>`
    |
    = help: the trait `Foo<char>` is implemented for `Bar`
-note: required by a bound in `Foo::{synthetic#0}`
+note: required by a bound in `Foo::{anon_assoc#0}`
   --> $DIR/return-dont-satisfy-bounds.rs:2:30
    |
 LL |     fn foo<F2>(self) -> impl Foo<T>;
-   |                              ^^^^^^ required by this bound in `Foo::{synthetic#0}`
+   |                              ^^^^^^ required by this bound in `Foo::{anon_assoc#0}`
 
 error[E0277]: the trait bound `Bar: Foo<u8>` is not satisfied
   --> $DIR/return-dont-satisfy-bounds.rs:8:34

tests/ui/rfcs/rfc-1937-termination-trait/issue-103052-2.stderr

@@ -4,11 +4,11 @@ error[E0277]: the trait bound `Something: Termination` is not satisfied
 LL |         fn main() -> Something {
    |                      ^^^^^^^^^ the trait `Termination` is not implemented for `Something`
    |
-note: required by a bound in `Main::{synthetic#0}`
+note: required by a bound in `Main::{anon_assoc#0}`
   --> $DIR/issue-103052-2.rs:3:27
    |
 LL |         fn main() -> impl std::process::Termination;
-   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Main::{synthetic#0}`
+   |                           ^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `Main::{anon_assoc#0}`
 
 error: aborting due to 1 previous error