Auto merge of #72114 - anyska:vtable-rename, r=nikomatsakis

Rename traits::Vtable to ImplSource.

Originally suggested by @eddyb.

r? @nikomatsakis

src/librustc_infer/traits/mod.rs

@@ -14,9 +14,9 @@ use rustc_middle::ty::{self, Const, Ty};
 use rustc_span::Span;
 
 pub use self::FulfillmentErrorCode::*;
+pub use self::ImplSource::*;
 pub use self::ObligationCauseCode::*;
 pub use self::SelectionError::*;
-pub use self::Vtable::*;
 
 pub use self::engine::{TraitEngine, TraitEngineExt};
 pub use self::project::MismatchedProjectionTypes;
@@ -30,10 +30,10 @@ crate use self::util::elaborate_predicates;
 pub use rustc_middle::traits::*;
 
 /// An `Obligation` represents some trait reference (e.g., `int: Eq`) for
-/// which the vtable must be found. The process of finding a vtable is
+/// which the "impl_source" must be found. The process of finding a "impl_source" is
 /// called "resolving" the `Obligation`. This process consists of
 /// either identifying an `impl` (e.g., `impl Eq for int`) that
-/// provides the required vtable, or else finding a bound that is in
+/// satisfies the obligation, or else finding a bound that is in
 /// scope. The eventual result is usually a `Selection` (defined below).
 #[derive(Clone, PartialEq, Eq, Hash)]
 pub struct Obligation<'tcx, T> {
@@ -65,7 +65,7 @@ pub type Obligations<'tcx, O> = Vec<Obligation<'tcx, O>>;
 pub type PredicateObligations<'tcx> = Vec<PredicateObligation<'tcx>>;
 pub type TraitObligations<'tcx> = Vec<TraitObligation<'tcx>>;
 
-pub type Selection<'tcx> = Vtable<'tcx, PredicateObligation<'tcx>>;
+pub type Selection<'tcx> = ImplSource<'tcx, PredicateObligation<'tcx>>;
 
 pub struct FulfillmentError<'tcx> {
     pub obligation: PredicateObligation<'tcx>,

src/librustc_middle/query/mod.rs

@@ -735,7 +735,7 @@ rustc_queries! {
     Codegen {
         query codegen_fulfill_obligation(
             key: (ty::ParamEnv<'tcx>, ty::PolyTraitRef<'tcx>)
-        ) -> Result<Vtable<'tcx, ()>, ErrorReported> {
+        ) -> Result<ImplSource<'tcx, ()>, ErrorReported> {
             cache_on_disk_if { true }
             desc { |tcx|
                 "checking if `{}` fulfills its obligations",

src/librustc_middle/traits/mod.rs

@@ -27,9 +27,9 @@ pub use self::select::{EvaluationCache, EvaluationResult, OverflowError, Selecti
 
 pub type ChalkCanonicalGoal<'tcx> = Canonical<'tcx, ChalkEnvironmentAndGoal<'tcx>>;
 
+pub use self::ImplSource::*;
 pub use self::ObligationCauseCode::*;
 pub use self::SelectionError::*;
-pub use self::Vtable::*;
 
 pub use self::chalk::{
     ChalkEnvironmentAndGoal, ChalkEnvironmentClause, RustDefId as ChalkRustDefId,
@@ -343,15 +343,10 @@ pub enum SelectionError<'tcx> {
 /// - `Err(e)`: error `e` occurred
 pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
 
-/// Given the successful resolution of an obligation, the `Vtable`
-/// indicates where the vtable comes from. Note that while we call this
-/// a "vtable", it does not necessarily indicate dynamic dispatch at
-/// runtime. `Vtable` instances just tell the compiler where to find
-/// methods, but in generic code those methods are typically statically
-/// dispatched -- only when an object is constructed is a `Vtable`
-/// instance reified into an actual vtable.
+/// Given the successful resolution of an obligation, the `ImplSource`
+/// indicates where the impl comes from.
 ///
-/// For example, the vtable may be tied to a specific impl (case A),
+/// For example, the obligation may be satisfied by a specific impl (case A),
 /// or it may be relative to some bound that is in scope (case B).
 ///
 /// ```
@@ -363,136 +358,136 @@ pub type SelectionResult<'tcx, T> = Result<Option<T>, SelectionError<'tcx>>;
 ///                 param: T,
 ///                 mixed: Option<T>) {
 ///
-///    // Case A: Vtable points at a specific impl. Only possible when
+///    // Case A: ImplSource points at a specific impl. Only possible when
 ///    // type is concretely known. If the impl itself has bounded
-///    // type parameters, Vtable will carry resolutions for those as well:
-///    concrete.clone(); // Vtable(Impl_1, [Vtable(Impl_2, [Vtable(Impl_3)])])
+///    // type parameters, ImplSource will carry resolutions for those as well:
+///    concrete.clone(); // ImplSource(Impl_1, [ImplSource(Impl_2, [ImplSource(Impl_3)])])
 ///
-///    // Case B: Vtable must be provided by caller. This applies when
+///    // Case B: ImplSource must be provided by caller. This applies when
 ///    // type is a type parameter.
-///    param.clone();    // VtableParam
+///    param.clone();    // ImplSourceParam
 ///
 ///    // Case C: A mix of cases A and B.
-///    mixed.clone();    // Vtable(Impl_1, [VtableParam])
+///    mixed.clone();    // ImplSource(Impl_1, [ImplSourceParam])
 /// }
 /// ```
 ///
 /// ### The type parameter `N`
 ///
-/// See explanation on `VtableImplData`.
+/// See explanation on `ImplSourceUserDefinedData`.
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub enum Vtable<'tcx, N> {
-    /// Vtable identifying a particular impl.
-    VtableImpl(VtableImplData<'tcx, N>),
+pub enum ImplSource<'tcx, N> {
+    /// ImplSource identifying a particular impl.
+    ImplSourceUserDefined(ImplSourceUserDefinedData<'tcx, N>),
 
-    /// Vtable for auto trait implementations.
+    /// ImplSource for auto trait implementations.
     /// This carries the information and nested obligations with regards
     /// to an auto implementation for a trait `Trait`. The nested obligations
     /// ensure the trait implementation holds for all the constituent types.
-    VtableAutoImpl(VtableAutoImplData<N>),
+    ImplSourceAutoImpl(ImplSourceAutoImplData<N>),
 
     /// Successful resolution to an obligation provided by the caller
     /// for some type parameter. The `Vec<N>` represents the
     /// obligations incurred from normalizing the where-clause (if
     /// any).
-    VtableParam(Vec<N>),
+    ImplSourceParam(Vec<N>),
 
     /// Virtual calls through an object.
-    VtableObject(VtableObjectData<'tcx, N>),
+    ImplSourceObject(ImplSourceObjectData<'tcx, N>),
 
     /// Successful resolution for a builtin trait.
-    VtableBuiltin(VtableBuiltinData<N>),
+    ImplSourceBuiltin(ImplSourceBuiltinData<N>),
 
-    /// Vtable automatically generated for a closure. The `DefId` is the ID
-    /// of the closure expression. This is a `VtableImpl` in spirit, but the
+    /// ImplSource automatically generated for a closure. The `DefId` is the ID
+    /// of the closure expression. This is a `ImplSourceUserDefined` in spirit, but the
     /// impl is generated by the compiler and does not appear in the source.
-    VtableClosure(VtableClosureData<'tcx, N>),
+    ImplSourceClosure(ImplSourceClosureData<'tcx, N>),
 
     /// Same as above, but for a function pointer type with the given signature.
-    VtableFnPointer(VtableFnPointerData<'tcx, N>),
+    ImplSourceFnPointer(ImplSourceFnPointerData<'tcx, N>),
 
-    /// Vtable for a builtin `DeterminantKind` trait implementation.
-    VtableDiscriminantKind(VtableDiscriminantKindData),
+    /// ImplSource for a builtin `DeterminantKind` trait implementation.
+    ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData),
 
-    /// Vtable automatically generated for a generator.
-    VtableGenerator(VtableGeneratorData<'tcx, N>),
+    /// ImplSource automatically generated for a generator.
+    ImplSourceGenerator(ImplSourceGeneratorData<'tcx, N>),
 
-    /// Vtable for a trait alias.
-    VtableTraitAlias(VtableTraitAliasData<'tcx, N>),
+    /// ImplSource for a trait alias.
+    ImplSourceTraitAlias(ImplSourceTraitAliasData<'tcx, N>),
 }
 
-impl<'tcx, N> Vtable<'tcx, N> {
+impl<'tcx, N> ImplSource<'tcx, N> {
     pub fn nested_obligations(self) -> Vec<N> {
         match self {
-            VtableImpl(i) => i.nested,
-            VtableParam(n) => n,
-            VtableBuiltin(i) => i.nested,
-            VtableAutoImpl(d) => d.nested,
-            VtableClosure(c) => c.nested,
-            VtableGenerator(c) => c.nested,
-            VtableObject(d) => d.nested,
-            VtableFnPointer(d) => d.nested,
-            VtableDiscriminantKind(VtableDiscriminantKindData) => Vec::new(),
-            VtableTraitAlias(d) => d.nested,
+            ImplSourceUserDefined(i) => i.nested,
+            ImplSourceParam(n) => n,
+            ImplSourceBuiltin(i) => i.nested,
+            ImplSourceAutoImpl(d) => d.nested,
+            ImplSourceClosure(c) => c.nested,
+            ImplSourceGenerator(c) => c.nested,
+            ImplSourceObject(d) => d.nested,
+            ImplSourceFnPointer(d) => d.nested,
+            ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) => Vec::new(),
+            ImplSourceTraitAlias(d) => d.nested,
         }
     }
 
     pub fn borrow_nested_obligations(&self) -> &[N] {
         match &self {
-            VtableImpl(i) => &i.nested[..],
-            VtableParam(n) => &n[..],
-            VtableBuiltin(i) => &i.nested[..],
-            VtableAutoImpl(d) => &d.nested[..],
-            VtableClosure(c) => &c.nested[..],
-            VtableGenerator(c) => &c.nested[..],
-            VtableObject(d) => &d.nested[..],
-            VtableFnPointer(d) => &d.nested[..],
-            VtableDiscriminantKind(VtableDiscriminantKindData) => &[],
-            VtableTraitAlias(d) => &d.nested[..],
+            ImplSourceUserDefined(i) => &i.nested[..],
+            ImplSourceParam(n) => &n[..],
+            ImplSourceBuiltin(i) => &i.nested[..],
+            ImplSourceAutoImpl(d) => &d.nested[..],
+            ImplSourceClosure(c) => &c.nested[..],
+            ImplSourceGenerator(c) => &c.nested[..],
+            ImplSourceObject(d) => &d.nested[..],
+            ImplSourceFnPointer(d) => &d.nested[..],
+            ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) => &[],
+            ImplSourceTraitAlias(d) => &d.nested[..],
         }
     }
 
-    pub fn map<M, F>(self, f: F) -> Vtable<'tcx, M>
+    pub fn map<M, F>(self, f: F) -> ImplSource<'tcx, M>
     where
         F: FnMut(N) -> M,
     {
         match self {
-            VtableImpl(i) => VtableImpl(VtableImplData {
+            ImplSourceUserDefined(i) => ImplSourceUserDefined(ImplSourceUserDefinedData {
                 impl_def_id: i.impl_def_id,
                 substs: i.substs,
                 nested: i.nested.into_iter().map(f).collect(),
             }),
-            VtableParam(n) => VtableParam(n.into_iter().map(f).collect()),
-            VtableBuiltin(i) => {
-                VtableBuiltin(VtableBuiltinData { nested: i.nested.into_iter().map(f).collect() })
-            }
-            VtableObject(o) => VtableObject(VtableObjectData {
+            ImplSourceParam(n) => ImplSourceParam(n.into_iter().map(f).collect()),
+            ImplSourceBuiltin(i) => ImplSourceBuiltin(ImplSourceBuiltinData {
+                nested: i.nested.into_iter().map(f).collect(),
+            }),
+            ImplSourceObject(o) => ImplSourceObject(ImplSourceObjectData {
                 upcast_trait_ref: o.upcast_trait_ref,
                 vtable_base: o.vtable_base,
                 nested: o.nested.into_iter().map(f).collect(),
             }),
-            VtableAutoImpl(d) => VtableAutoImpl(VtableAutoImplData {
+            ImplSourceAutoImpl(d) => ImplSourceAutoImpl(ImplSourceAutoImplData {
                 trait_def_id: d.trait_def_id,
                 nested: d.nested.into_iter().map(f).collect(),
             }),
-            VtableClosure(c) => VtableClosure(VtableClosureData {
+            ImplSourceClosure(c) => ImplSourceClosure(ImplSourceClosureData {
                 closure_def_id: c.closure_def_id,
                 substs: c.substs,
                 nested: c.nested.into_iter().map(f).collect(),
             }),
-            VtableGenerator(c) => VtableGenerator(VtableGeneratorData {
+            ImplSourceGenerator(c) => ImplSourceGenerator(ImplSourceGeneratorData {
                 generator_def_id: c.generator_def_id,
                 substs: c.substs,
                 nested: c.nested.into_iter().map(f).collect(),
             }),
-            VtableFnPointer(p) => VtableFnPointer(VtableFnPointerData {
+            ImplSourceFnPointer(p) => ImplSourceFnPointer(ImplSourceFnPointerData {
                 fn_ty: p.fn_ty,
                 nested: p.nested.into_iter().map(f).collect(),
             }),
-            VtableDiscriminantKind(VtableDiscriminantKindData) => {
-                VtableDiscriminantKind(VtableDiscriminantKindData)
+            ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData) => {
+                ImplSourceDiscriminantKind(ImplSourceDiscriminantKindData)
             }
-            VtableTraitAlias(d) => VtableTraitAlias(VtableTraitAliasData {
+            ImplSourceTraitAlias(d) => ImplSourceTraitAlias(ImplSourceTraitAliasData {
                 alias_def_id: d.alias_def_id,
                 substs: d.substs,
                 nested: d.nested.into_iter().map(f).collect(),
@@ -512,14 +507,14 @@ impl<'tcx, N> Vtable<'tcx, N> {
 /// is `()`, because codegen only requires a shallow resolution of an
 /// impl, and nested obligations are satisfied later.
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableImplData<'tcx, N> {
+pub struct ImplSourceUserDefinedData<'tcx, N> {
     pub impl_def_id: DefId,
     pub substs: SubstsRef<'tcx>,
     pub nested: Vec<N>,
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableGeneratorData<'tcx, N> {
+pub struct ImplSourceGeneratorData<'tcx, N> {
     pub generator_def_id: DefId,
     pub substs: SubstsRef<'tcx>,
     /// Nested obligations. This can be non-empty if the generator
@@ -528,7 +523,7 @@ pub struct VtableGeneratorData<'tcx, N> {
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableClosureData<'tcx, N> {
+pub struct ImplSourceClosureData<'tcx, N> {
     pub closure_def_id: DefId,
     pub substs: SubstsRef<'tcx>,
     /// Nested obligations. This can be non-empty if the closure
@@ -537,20 +532,18 @@ pub struct VtableClosureData<'tcx, N> {
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableAutoImplData<N> {
+pub struct ImplSourceAutoImplData<N> {
     pub trait_def_id: DefId,
     pub nested: Vec<N>,
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableBuiltinData<N> {
+pub struct ImplSourceBuiltinData<N> {
     pub nested: Vec<N>,
 }
 
-/// A vtable for some object-safe trait `Foo` automatically derived
-/// for the object type `Foo`.
 #[derive(PartialEq, Eq, Clone, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableObjectData<'tcx, N> {
+pub struct ImplSourceObjectData<'tcx, N> {
     /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
     pub upcast_trait_ref: ty::PolyTraitRef<'tcx>,
 
@@ -563,17 +556,17 @@ pub struct VtableObjectData<'tcx, N> {
 }
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableFnPointerData<'tcx, N> {
+pub struct ImplSourceFnPointerData<'tcx, N> {
     pub fn_ty: Ty<'tcx>,
     pub nested: Vec<N>,
 }
 
 // FIXME(@lcnr): This should be  refactored and merged with other builtin vtables.
 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableDiscriminantKindData;
+pub struct ImplSourceDiscriminantKindData;
 
 #[derive(Clone, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable, TypeFoldable)]
-pub struct VtableTraitAliasData<'tcx, N> {
+pub struct ImplSourceTraitAliasData<'tcx, N> {
     pub alias_def_id: DefId,
     pub substs: SubstsRef<'tcx>,
     pub nested: Vec<N>,