Uplift VarianceDiagInfo

compiler/rustc_borrowck/src/constraints/mod.rs

@@ -97,7 +97,7 @@ pub struct OutlivesConstraint<'tcx> {
     pub category: ConstraintCategory<'tcx>,
 
     /// Variance diagnostic information
-    pub variance_info: VarianceDiagInfo<'tcx>,
+    pub variance_info: VarianceDiagInfo<TyCtxt<'tcx>>,
 
     /// If this constraint is promoted from closure requirements.
     pub from_closure: bool,

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -2304,5 +2304,5 @@ pub struct BlameConstraint<'tcx> {
     pub category: ConstraintCategory<'tcx>,
     pub from_closure: bool,
     pub cause: ObligationCause<'tcx>,
-    pub variance_info: ty::VarianceDiagInfo<'tcx>,
+    pub variance_info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
 }

compiler/rustc_borrowck/src/type_check/relate_tys.rs

@@ -82,7 +82,7 @@ pub struct NllTypeRelating<'me, 'bccx, 'tcx> {
     /// - Bivariant means that it doesn't matter.
     ambient_variance: ty::Variance,
 
-    ambient_variance_info: ty::VarianceDiagInfo<'tcx>,
+    ambient_variance_info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
 }
 
 impl<'me, 'bccx, 'tcx> NllTypeRelating<'me, 'bccx, 'tcx> {
@@ -296,7 +296,7 @@ impl<'me, 'bccx, 'tcx> NllTypeRelating<'me, 'bccx, 'tcx> {
         &mut self,
         sup: ty::Region<'tcx>,
         sub: ty::Region<'tcx>,
-        info: ty::VarianceDiagInfo<'tcx>,
+        info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
     ) {
         let sub = self.type_checker.borrowck_context.universal_regions.to_region_vid(sub);
         let sup = self.type_checker.borrowck_context.universal_regions.to_region_vid(sup);
@@ -327,7 +327,7 @@ impl<'bccx, 'tcx> TypeRelation<'tcx> for NllTypeRelating<'_, 'bccx, 'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        info: ty::VarianceDiagInfo<'tcx>,
+        info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2707,7 +2707,7 @@ impl<'tcx> TypeRelation<'tcx> for SameTypeModuloInfer<'_, 'tcx> {
     fn relate_with_variance<T: relate::Relate<'tcx>>(
         &mut self,
         _variance: ty::Variance,
-        _info: ty::VarianceDiagInfo<'tcx>,
+        _info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> relate::RelateResult<'tcx, T> {

compiler/rustc_infer/src/infer/outlives/test_type_match.rs

@@ -148,7 +148,7 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstHigherRankedOutlives<'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        _: ty::VarianceDiagInfo<'tcx>,
+        _: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_infer/src/infer/relate/generalize.rs

@@ -425,7 +425,7 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        _info: ty::VarianceDiagInfo<'tcx>,
+        _info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_infer/src/infer/relate/glb.rs

@@ -33,7 +33,7 @@ impl<'tcx> TypeRelation<'tcx> for Glb<'_, '_, 'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        _info: ty::VarianceDiagInfo<'tcx>,
+        _info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_infer/src/infer/relate/lub.rs

@@ -33,7 +33,7 @@ impl<'tcx> TypeRelation<'tcx> for Lub<'_, '_, 'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        _info: ty::VarianceDiagInfo<'tcx>,
+        _info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_infer/src/infer/relate/type_relating.rs

@@ -59,7 +59,7 @@ impl<'tcx> TypeRelation<'tcx> for TypeRelating<'_, '_, 'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        _info: ty::VarianceDiagInfo<'tcx>,
+        _info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_middle/src/ty/_match.rs

@@ -41,7 +41,7 @@ impl<'tcx> TypeRelation<'tcx> for MatchAgainstFreshVars<'tcx> {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         _: ty::Variance,
-        _: ty::VarianceDiagInfo<'tcx>,
+        _: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T> {

compiler/rustc_middle/src/ty/mod.rs

@@ -114,7 +114,7 @@ pub use self::rvalue_scopes::RvalueScopes;
 pub use self::sty::{
     AliasTy, Article, Binder, BoundTy, BoundTyKind, BoundVariableKind, CanonicalPolyFnSig,
     CoroutineArgsExt, EarlyBinder, FnSig, InlineConstArgs, InlineConstArgsParts, ParamConst,
-    ParamTy, PolyFnSig, TyKind, TypeAndMut, UpvarArgs, VarianceDiagInfo,
+    ParamTy, PolyFnSig, TyKind, TypeAndMut, UpvarArgs,
 };
 pub use self::trait_def::TraitDef;
 pub use self::typeck_results::{

compiler/rustc_middle/src/ty/relate.rs

@@ -54,7 +54,7 @@ pub trait TypeRelation<'tcx>: Sized {
     fn relate_with_variance<T: Relate<'tcx>>(
         &mut self,
         variance: ty::Variance,
-        info: ty::VarianceDiagInfo<'tcx>,
+        info: ty::VarianceDiagInfo<TyCtxt<'tcx>>,
         a: T,
         b: T,
     ) -> RelateResult<'tcx, T>;

compiler/rustc_middle/src/ty/sty.rs

@@ -1790,43 +1790,6 @@ impl<'tcx> rustc_type_ir::inherent::Tys<TyCtxt<'tcx>> for &'tcx ty::List<Ty<'tcx
     }
 }
 
-/// Extra information about why we ended up with a particular variance.
-/// This is only used to add more information to error messages, and
-/// has no effect on soundness. While choosing the 'wrong' `VarianceDiagInfo`
-/// may lead to confusing notes in error messages, it will never cause
-/// a miscompilation or unsoundness.
-///
-/// When in doubt, use `VarianceDiagInfo::default()`
-#[derive(Copy, Clone, Debug, Default, PartialEq, Eq)]
-pub enum VarianceDiagInfo<'tcx> {
-    /// No additional information - this is the default.
-    /// We will not add any additional information to error messages.
-    #[default]
-    None,
-    /// We switched our variance because a generic argument occurs inside
-    /// the invariant generic argument of another type.
-    Invariant {
-        /// The generic type containing the generic parameter
-        /// that changes the variance (e.g. `*mut T`, `MyStruct<T>`)
-        ty: Ty<'tcx>,
-        /// The index of the generic parameter being used
-        /// (e.g. `0` for `*mut T`, `1` for `MyStruct<'CovariantParam, 'InvariantParam>`)
-        param_index: u32,
-    },
-}
-
-impl<'tcx> VarianceDiagInfo<'tcx> {
-    /// Mirrors `Variance::xform` - used to 'combine' the existing
-    /// and new `VarianceDiagInfo`s when our variance changes.
-    pub fn xform(self, other: VarianceDiagInfo<'tcx>) -> VarianceDiagInfo<'tcx> {
-        // For now, just use the first `VarianceDiagInfo::Invariant` that we see
-        match self {
-            VarianceDiagInfo::None => other,
-            VarianceDiagInfo::Invariant { .. } => self,
-        }
-    }
-}
-
 // Some types are used a lot. Make sure they don't unintentionally get bigger.
 #[cfg(target_pointer_width = "64")]
 mod size_asserts {