Auto merge of #59331 - varkor:TypeVariableOrigin-refactor, r=eddyb

Refactor `TypeVariableOrigin`

Removes some unused variants and extracts the common `Span` field.

As suggested in #59008 (comment).

r? @eddyb

src/librustc/infer/canonical/mod.rs

@@ -21,7 +21,8 @@
 //!
 //! [c]: https://rust-lang.github.io/rustc-guide/traits/canonicalization.html
 
-use crate::infer::{InferCtxt, RegionVariableOrigin, TypeVariableOrigin, ConstVariableOrigin};
+use crate::infer::{InferCtxt, RegionVariableOrigin, TypeVariableOrigin, TypeVariableOriginKind};
+use crate::infer::{ConstVariableOrigin, ConstVariableOriginKind};
 use crate::mir::interpret::ConstValue;
 use rustc_data_structures::indexed_vec::IndexVec;
 use rustc_macros::HashStable;
@@ -365,7 +366,10 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
                 let ty = match ty_kind {
                     CanonicalTyVarKind::General(ui) => {
                         self.next_ty_var_in_universe(
-                            TypeVariableOrigin::MiscVariable(span),
+                            TypeVariableOrigin {
+                                kind: TypeVariableOriginKind::MiscVariable,
+                                span,
+                            },
                             universe_map(ui)
                         )
                     }
@@ -403,10 +407,16 @@ impl<'cx, 'gcx, 'tcx> InferCtxt<'cx, 'gcx, 'tcx> {
             CanonicalVarKind::Const(ui) => {
                 self.next_const_var_in_universe(
                     self.next_ty_var_in_universe(
-                        TypeVariableOrigin::MiscVariable(span),
+                        TypeVariableOrigin {
+                            kind: TypeVariableOriginKind::MiscVariable,
+                            span,
+                        },
                         universe_map(ui),
                     ),
-                    ConstVariableOrigin::MiscVariable(span),
+                    ConstVariableOrigin {
+                        kind: ConstVariableOriginKind::MiscVariable,
+                        span,
+                    },
                     universe_map(ui),
                 ).into()
             }

src/librustc/infer/combine.rs

@@ -28,7 +28,8 @@ use super::{InferCtxt, MiscVariable, TypeTrace};
 use super::lub::Lub;
 use super::sub::Sub;
 use super::type_variable::TypeVariableValue;
-use super::unify_key::{ConstVarValue, ConstVariableValue, ConstVariableOrigin};
+use super::unify_key::{ConstVarValue, ConstVariableValue};
+use super::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 
 use crate::hir::def_id::DefId;
 use crate::mir::interpret::ConstValue;
@@ -165,7 +166,10 @@ impl<'infcx, 'gcx, 'tcx> InferCtxt<'infcx, 'gcx, 'tcx> {
         self.const_unification_table
             .borrow_mut()
             .unify_var_value(vid, ConstVarValue {
-                origin: ConstVariableOrigin::ConstInference(DUMMY_SP),
+                origin: ConstVariableOrigin {
+                    kind: ConstVariableOriginKind::ConstInference,
+                    span: DUMMY_SP,
+                },
                 val: ConstVariableValue::Known { value },
             })
             .map_err(|e| const_unification_error(vid_is_expected, e))?;

src/librustc/infer/error_reporting/need_type_info.rs

@@ -2,7 +2,7 @@ use crate::hir::def::Namespace;
 use crate::hir::{self, Local, Pat, Body, HirId};
 use crate::hir::intravisit::{self, Visitor, NestedVisitorMap};
 use crate::infer::InferCtxt;
-use crate::infer::type_variable::TypeVariableOrigin;
+use crate::infer::type_variable::TypeVariableOriginKind;
 use crate::ty::{self, Ty, Infer, TyVar};
 use crate::ty::print::Print;
 use syntax::source_map::CompilerDesugaringKind;
@@ -83,8 +83,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
     ) -> String {
         if let ty::Infer(ty::TyVar(ty_vid)) = ty.sty {
             let ty_vars = self.type_variables.borrow();
-            if let TypeVariableOrigin::TypeParameterDefinition(_, name) =
-                *ty_vars.var_origin(ty_vid) {
+            if let TypeVariableOriginKind::TypeParameterDefinition(name) =
+                ty_vars.var_origin(ty_vid).kind {
                 return name.to_string();
             }
         }
@@ -122,8 +122,8 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
             let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
             let ty_vars = self.type_variables.borrow();
             let getter = move |ty_vid| {
-                if let TypeVariableOrigin::TypeParameterDefinition(_, name) =
-                    *ty_vars.var_origin(ty_vid) {
+                if let TypeVariableOriginKind::TypeParameterDefinition(name) =
+                    ty_vars.var_origin(ty_vid).kind {
                     return Some(name.to_string());
                 }
                 None

src/librustc/infer/lattice.rs

@@ -20,7 +20,7 @@
 //! a lattice.
 
 use super::InferCtxt;
-use super::type_variable::TypeVariableOrigin;
+use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 
 use crate::traits::ObligationCause;
 use crate::ty::TyVar;
@@ -79,12 +79,18 @@ pub fn super_lattice_tys<'a, 'gcx, 'tcx, L>(this: &mut L,
         // iterate on the subtype obligations that are returned, but I
         // think this suffices. -nmatsakis
         (&ty::Infer(TyVar(..)), _) => {
-            let v = infcx.next_ty_var(TypeVariableOrigin::LatticeVariable(this.cause().span));
+            let v = infcx.next_ty_var(TypeVariableOrigin {
+                kind: TypeVariableOriginKind::LatticeVariable,
+                span: this.cause().span,
+            });
             this.relate_bound(v, b, a)?;
             Ok(v)
         }
         (_, &ty::Infer(TyVar(..))) => {
-            let v = infcx.next_ty_var(TypeVariableOrigin::LatticeVariable(this.cause().span));
+            let v = infcx.next_ty_var(TypeVariableOrigin {
+                kind: TypeVariableOriginKind::LatticeVariable,
+                span: this.cause().span,
+            });
             this.relate_bound(v, a, b)?;
             Ok(v)
         }

src/librustc/infer/mod.rs

@@ -39,8 +39,8 @@ use self::lexical_region_resolve::LexicalRegionResolutions;
 use self::outlives::env::OutlivesEnvironment;
 use self::region_constraints::{GenericKind, RegionConstraintData, VarInfos, VerifyBound};
 use self::region_constraints::{RegionConstraintCollector, RegionSnapshot};
-use self::type_variable::TypeVariableOrigin;
-use self::unify_key::{ToType, ConstVariableOrigin};
+use self::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
+use self::unify_key::{ToType, ConstVariableOrigin, ConstVariableOriginKind};
 
 pub mod at;
 pub mod canonical;
@@ -1110,13 +1110,19 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                 let ty_var_id = self.type_variables.borrow_mut().new_var(
                     self.universe(),
                     false,
-                    TypeVariableOrigin::TypeParameterDefinition(span, param.name),
+                    TypeVariableOrigin {
+                        kind: TypeVariableOriginKind::TypeParameterDefinition(param.name),
+                        span,
+                    },
                 );
 
                 self.tcx.mk_ty_var(ty_var_id).into()
             }
             GenericParamDefKind::Const { .. } => {
-                let origin = ConstVariableOrigin::ConstParameterDefinition(span, param.name);
+                let origin = ConstVariableOrigin {
+                    kind: ConstVariableOriginKind::ConstParameterDefinition(param.name),
+                    span,
+                };
                 let const_var_id =
                     self.const_unification_table
                         .borrow_mut()
@@ -1412,8 +1418,16 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
         T: TypeFoldable<'tcx>
     {
         let fld_r = |br| self.next_region_var(LateBoundRegion(span, br, lbrct));
-        let fld_t = |_| self.next_ty_var(TypeVariableOrigin::MiscVariable(span));
-        let fld_c = |_, ty| self.next_const_var(ty, ConstVariableOrigin::MiscVariable(span));
+        let fld_t = |_| {
+            self.next_ty_var(TypeVariableOrigin {
+                kind: TypeVariableOriginKind::MiscVariable,
+                span,
+            })
+        };
+        let fld_c = |_, ty| self.next_const_var(ty, ConstVariableOrigin {
+            kind: ConstVariableOriginKind:: MiscVariable,
+            span,
+        });
         self.tcx.replace_bound_vars(value, fld_r, fld_t, fld_c)
     }
 

src/librustc/infer/nll_relate/mod.rs

@@ -270,15 +270,16 @@ where
         projection_ty: ty::ProjectionTy<'tcx>,
         value_ty: Ty<'tcx>,
     ) -> Ty<'tcx> {
-        use crate::infer::type_variable::TypeVariableOrigin;
+        use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
         use crate::traits::WhereClause;
         use syntax_pos::DUMMY_SP;
 
         match value_ty.sty {
             ty::Projection(other_projection_ty) => {
-                let var = self
-                    .infcx
-                    .next_ty_var(TypeVariableOrigin::MiscVariable(DUMMY_SP));
+                let var = self.infcx.next_ty_var(TypeVariableOrigin {
+                    kind: TypeVariableOriginKind::MiscVariable,
+                    span: DUMMY_SP,
+                });
                 self.relate_projection_ty(projection_ty, var);
                 self.relate_projection_ty(other_projection_ty, var);
                 var

src/librustc/infer/opaque_types/mod.rs

@@ -4,7 +4,7 @@ use syntax_pos::Span;
 use crate::hir::def_id::DefId;
 use crate::hir;
 use crate::hir::Node;
-use crate::infer::{self, InferCtxt, InferOk, TypeVariableOrigin};
+use crate::infer::{self, InferCtxt, InferOk, TypeVariableOrigin, TypeVariableOriginKind};
 use crate::infer::outlives::free_region_map::FreeRegionRelations;
 use crate::traits::{self, PredicateObligation};
 use crate::ty::{self, Ty, TyCtxt, GenericParamDefKind};
@@ -864,7 +864,10 @@ impl<'a, 'gcx, 'tcx> Instantiator<'a, 'gcx, 'tcx> {
             return opaque_defn.concrete_ty;
         }
         let span = tcx.def_span(def_id);
-        let ty_var = infcx.next_ty_var(TypeVariableOrigin::TypeInference(span));
+        let ty_var = infcx.next_ty_var(TypeVariableOrigin {
+            kind: TypeVariableOriginKind::TypeInference,
+            span,
+        });
 
         let predicates_of = tcx.predicates_of(def_id);
         debug!(

src/librustc/infer/resolve.rs

@@ -1,4 +1,5 @@
-use super::{InferCtxt, FixupError, FixupResult, Span, type_variable::TypeVariableOrigin};
+use super::{InferCtxt, FixupError, FixupResult, Span};
+use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::mir::interpret::ConstValue;
 use crate::ty::{self, Ty, Const, TyCtxt, TypeFoldable, InferConst, TypeFlags};
 use crate::ty::fold::{TypeFolder, TypeVisitor};
@@ -123,8 +124,10 @@ impl<'a, 'gcx, 'tcx> TypeVisitor<'tcx> for UnresolvedTypeFinder<'a, 'gcx, 'tcx>
                 let ty_var_span =
                 if let ty::TyVar(ty_vid) = infer_ty {
                     let ty_vars = self.infcx.type_variables.borrow();
-                    if let TypeVariableOrigin::TypeParameterDefinition(span, _name)
-                        = *ty_vars.var_origin(ty_vid)
+                    if let TypeVariableOrigin {
+                        kind: TypeVariableOriginKind::TypeParameterDefinition(_),
+                        span,
+                    } = *ty_vars.var_origin(ty_vid)
                     {
                         Some(span)
                     } else {

src/librustc/infer/type_variable.rs

@@ -37,25 +37,28 @@ pub struct TypeVariableTable<'tcx> {
     sub_relations: ut::UnificationTable<ut::InPlace<ty::TyVid>>,
 }
 
+#[derive(Copy, Clone, Debug)]
+pub struct TypeVariableOrigin {
+    pub kind: TypeVariableOriginKind,
+    pub span: Span,
+}
+
 /// Reasons to create a type inference variable
 #[derive(Copy, Clone, Debug)]
-pub enum TypeVariableOrigin {
-    MiscVariable(Span),
-    NormalizeProjectionType(Span),
-    TypeInference(Span),
-    TypeParameterDefinition(Span, InternedString),
-
-    /// one of the upvars or closure kind parameters in a `ClosureSubsts`
-    /// (before it has been determined)
-    ClosureSynthetic(Span),
-    SubstitutionPlaceholder(Span),
-    AutoDeref(Span),
-    AdjustmentType(Span),
-    DivergingStmt(Span),
-    DivergingBlockExpr(Span),
-    DivergingFn(Span),
-    LatticeVariable(Span),
-    Generalized(ty::TyVid),
+pub enum TypeVariableOriginKind {
+    MiscVariable,
+    NormalizeProjectionType,
+    TypeInference,
+    TypeParameterDefinition(InternedString),
+
+    /// One of the upvars or closure kind parameters in a `ClosureSubsts`
+    /// (before it has been determined).
+    ClosureSynthetic,
+    SubstitutionPlaceholder,
+    AutoDeref,
+    AdjustmentType,
+    DivergingFn,
+    LatticeVariable,
 }
 
 struct TypeVariableData {

src/librustc/infer/unify_key.rs

@@ -79,13 +79,19 @@ impl ToType for FloatVarValue {
 
 // Generic consts.
 
+#[derive(Copy, Clone, Debug)]
+pub struct ConstVariableOrigin {
+    pub kind: ConstVariableOriginKind,
+    pub span: Span,
+}
+
 /// Reasons to create a const inference variable
 #[derive(Copy, Clone, Debug)]
-pub enum ConstVariableOrigin {
-    MiscVariable(Span),
-    ConstInference(Span),
-    ConstParameterDefinition(Span, InternedString),
-    SubstitutionPlaceholder(Span),
+pub enum ConstVariableOriginKind {
+    MiscVariable,
+    ConstInference,
+    ConstParameterDefinition(InternedString),
+    SubstitutionPlaceholder,
 }
 
 #[derive(Copy, Clone, Debug)]
@@ -159,7 +165,10 @@ impl<'tcx> UnifyValue for ConstVarValue<'tcx> {
         }?;
 
         Ok(ConstVarValue {
-            origin: ConstVariableOrigin::ConstInference(DUMMY_SP),
+            origin: ConstVariableOrigin {
+                kind: ConstVariableOriginKind::ConstInference,
+                span: DUMMY_SP,
+            },
             val,
         })
     }

src/librustc/traits/error_reporting.rs

@@ -21,7 +21,7 @@ use crate::hir;
 use crate::hir::Node;
 use crate::hir::def_id::DefId;
 use crate::infer::{self, InferCtxt};
-use crate::infer::type_variable::TypeVariableOrigin;
+use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::session::DiagnosticMessageId;
 use crate::ty::{self, AdtKind, ToPredicate, ToPolyTraitRef, Ty, TyCtxt, TypeFoldable};
 use crate::ty::GenericParamDefKind;
@@ -1464,7 +1464,12 @@ impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
                     let infcx = self.infcx;
                     self.var_map.entry(ty).or_insert_with(||
                         infcx.next_ty_var(
-                            TypeVariableOrigin::TypeParameterDefinition(DUMMY_SP, name)))
+                            TypeVariableOrigin {
+                                kind: TypeVariableOriginKind::TypeParameterDefinition(name),
+                                span: DUMMY_SP,
+                            }
+                        )
+                    )
                 } else {
                     ty.super_fold_with(self)
                 }

src/librustc/traits/project.rs

@@ -14,7 +14,7 @@ use super::util;
 
 use crate::hir::def_id::DefId;
 use crate::infer::{InferCtxt, InferOk, LateBoundRegionConversionTime};
-use crate::infer::type_variable::TypeVariableOrigin;
+use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use crate::mir::interpret::{GlobalId, ConstValue};
 use rustc_data_structures::snapshot_map::{Snapshot, SnapshotMap};
 use rustc_macros::HashStable;
@@ -475,7 +475,11 @@ pub fn normalize_projection_type<'a, 'b, 'gcx, 'tcx>(
             let tcx = selcx.infcx().tcx;
             let def_id = projection_ty.item_def_id;
             let ty_var = selcx.infcx().next_ty_var(
-                TypeVariableOrigin::NormalizeProjectionType(tcx.def_span(def_id)));
+                TypeVariableOrigin {
+                    kind: TypeVariableOriginKind::NormalizeProjectionType,
+                    span: tcx.def_span(def_id),
+                },
+            );
             let projection = ty::Binder::dummy(ty::ProjectionPredicate {
                 projection_ty,
                 ty: ty_var
@@ -810,7 +814,11 @@ fn normalize_to_error<'a, 'gcx, 'tcx>(selcx: &mut SelectionContext<'a, 'gcx, 'tc
     let tcx = selcx.infcx().tcx;
     let def_id = projection_ty.item_def_id;
     let new_value = selcx.infcx().next_ty_var(
-        TypeVariableOrigin::NormalizeProjectionType(tcx.def_span(def_id)));
+        TypeVariableOrigin {
+            kind: TypeVariableOriginKind::NormalizeProjectionType,
+            span: tcx.def_span(def_id),
+        },
+    );
     Normalized {
         value: new_value,
         obligations: vec![trait_obligation]

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -26,7 +26,7 @@ use rustc::hir::def_id::DefId;
 use rustc::infer::canonical::QueryRegionConstraint;
 use rustc::infer::outlives::env::RegionBoundPairs;
 use rustc::infer::{InferCtxt, InferOk, LateBoundRegionConversionTime, NLLRegionVariableOrigin};
-use rustc::infer::type_variable::TypeVariableOrigin;
+use rustc::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use rustc::mir::interpret::{InterpError::BoundsCheck, ConstValue};
 use rustc::mir::tcx::PlaceTy;
 use rustc::mir::visit::{PlaceContext, Visitor, NonMutatingUseContext};
@@ -2209,7 +2209,10 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                 if let ty::RawPtr(_) | ty::FnPtr(_) = ty_left.sty {
                     let ty_right = right.ty(mir, tcx);
                     let common_ty = self.infcx.next_ty_var(
-                        TypeVariableOrigin::MiscVariable(mir.source_info(location).span),
+                        TypeVariableOrigin {
+                            kind: TypeVariableOriginKind::MiscVariable,
+                            span: mir.source_info(location).span,
+                        }
                     );
                     self.sub_types(
                         common_ty,