[CRATER] separate type equality from mutual subtyping

compiler/rustc_infer/src/infer/combine.rs

@@ -749,9 +749,7 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                     }
                 }
             }
-            ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted })
-                if self.tcx().lazy_normalization() =>
-            {
+            ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted }) => {
                 assert_eq!(promoted, None);
                 let substs = self.relate_with_variance(
                     ty::Variance::Invariant,
@@ -980,9 +978,7 @@ impl<'tcx> TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
                     }
                 }
             }
-            ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted })
-                if self.tcx().lazy_normalization() =>
-            {
+            ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted }) => {
                 assert_eq!(promoted, None);
                 let substs = self.relate_with_variance(
                     ty::Variance::Invariant,

compiler/rustc_infer/src/infer/equate.rs

@@ -1,6 +1,7 @@
 use super::combine::{CombineFields, ConstEquateRelation, RelationDir};
 use super::Subtype;
 
+use rustc_middle::ty::error::TypeError;
 use rustc_middle::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::TyVar;
@@ -151,13 +152,16 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> {
     where
         T: Relate<'tcx>,
     {
-        if a.skip_binder().has_escaping_bound_vars() || b.skip_binder().has_escaping_bound_vars() {
-            self.fields.higher_ranked_sub(a, b, self.a_is_expected)?;
-            self.fields.higher_ranked_sub(b, a, self.a_is_expected)
+        let a = self.tcx().anonymize_late_bound_regions(a);
+        let b = self.tcx().anonymize_late_bound_regions(b);
+        if a.bound_vars() == b.bound_vars() {
+            let (a, b) = self
+                .fields
+                .infcx
+                .replace_bound_vars_with_placeholders(a.map_bound(|a| (a, b.skip_binder())));
+            Ok(ty::Binder::dummy(self.relate(a, b)?))
         } else {
-            // Fast path for the common case.
-            self.relate(a.skip_binder(), b.skip_binder())?;
-            Ok(a)
+            Err(TypeError::Mismatch)
         }
     }
 }

compiler/rustc_trait_selection/src/traits/wf.rs

@@ -432,19 +432,22 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
                 GenericArgKind::Const(constant) => {
                     match constant.val() {
                         ty::ConstKind::Unevaluated(uv) => {
-                            let obligations = self.nominal_obligations(uv.def.did, uv.substs);
-                            self.out.extend(obligations);
-
-                            let predicate =
-                                ty::Binder::dummy(ty::PredicateKind::ConstEvaluatable(uv.shrink()))
-                                    .to_predicate(self.tcx());
-                            let cause = self.cause(traits::MiscObligation);
-                            self.out.push(traits::Obligation::with_depth(
-                                cause,
-                                self.recursion_depth,
-                                self.param_env,
-                                predicate,
-                            ));
+                            if !uv.has_escaping_bound_vars() {
+                                let obligations = self.nominal_obligations(uv.def.did, uv.substs);
+                                self.out.extend(obligations);
+
+                                let predicate = ty::Binder::dummy(
+                                    ty::PredicateKind::ConstEvaluatable(uv.shrink()),
+                                )
+                                .to_predicate(self.tcx());
+                                let cause = self.cause(traits::MiscObligation);
+                                self.out.push(traits::Obligation::with_depth(
+                                    cause,
+                                    self.recursion_depth,
+                                    self.param_env,
+                                    predicate,
+                                ));
+                            }
                         }
                         ty::ConstKind::Infer(infer) => {
                             let resolved = self.infcx.shallow_resolve(infer);

compiler/rustc_ty_utils/src/instance.rs

@@ -148,6 +148,7 @@ fn inner_resolve_instance<'tcx>(
 
     let result = if let Some(trait_def_id) = tcx.trait_of_item(def.did) {
         debug!(" => associated item, attempting to find impl in param_env {:#?}", param_env);
+        let substs = tcx.normalize_erasing_regions(param_env, substs);
         resolve_associated_item(tcx, def.did, param_env, trait_def_id, substs)
     } else {
         let ty = tcx.type_of(def.def_id_for_type_of());

compiler/rustc_typeck/src/check/intrinsic.rs

@@ -115,9 +115,13 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
     let name_str = intrinsic_name.as_str();
 
     let bound_vars = tcx.mk_bound_variable_kinds(
-        [ty::BoundVariableKind::Region(ty::BrAnon(0)), ty::BoundVariableKind::Region(ty::BrEnv)]
-            .iter()
-            .copied(),
+        [
+            ty::BoundVariableKind::Region(ty::BrAnon(0)),
+            ty::BoundVariableKind::Region(ty::BrAnon(1)),
+            ty::BoundVariableKind::Region(ty::BrEnv),
+        ]
+        .iter()
+        .copied(),
     );
     let mk_va_list_ty = |mutbl| {
         tcx.lang_items().va_list().map(|did| {
@@ -127,7 +131,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
             ));
             let env_region = tcx.mk_region(ty::ReLateBound(
                 ty::INNERMOST,
-                ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrEnv },
+                ty::BoundRegion { var: ty::BoundVar::from_u32(2), kind: ty::BrEnv },
             ));
             let va_list_ty = tcx.bound_type_of(did).subst(tcx, &[region.into()]);
             (tcx.mk_ref(env_region, ty::TypeAndMut { ty: va_list_ty, mutbl }), va_list_ty)
@@ -391,9 +395,12 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
 
             sym::raw_eq => {
                 let br = ty::BoundRegion { var: ty::BoundVar::from_u32(0), kind: ty::BrAnon(0) };
-                let param_ty =
+                let param_ty_lhs =
                     tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)), param(0));
-                (1, vec![param_ty; 2], tcx.types.bool)
+                let br = ty::BoundRegion { var: ty::BoundVar::from_u32(1), kind: ty::BrAnon(1) };
+                let param_ty_rhs =
+                    tcx.mk_imm_ref(tcx.mk_region(ty::ReLateBound(ty::INNERMOST, br)), param(0));
+                (1, vec![param_ty_lhs, param_ty_rhs], tcx.types.bool)
             }
 
             sym::black_box => (1, vec![param(0)], param(0)),

src/test/ui/closure-expected-type/expect-fn-supply-fn.base.stderr

@@ -36,33 +36,58 @@ note: ...does not necessarily outlive the anonymous lifetime #1 defined here
 LL |     with_closure_expecting_fn_with_free_region(|x: fn(&'x u32), y| {});
    |                                                ^^^^^^^^^^^^^^^^^^^^^^
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:38:52
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:36:5
    |
 LL |     with_closure_expecting_fn_with_free_region(|x: fn(&u32), y| {});
-   |                                                    ^^^^^^^^ one type is more general than the other
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ---------------- found signature of `fn(for<'r> fn(&'r u32), _) -> _`
+   |     |
+   |     expected signature of `for<'a, 'r> fn(for<'a> fn(&'a u32), &'r i32) -> _`
    |
-   = note: expected fn pointer `fn(&u32)`
-              found fn pointer `for<'r> fn(&'r u32)`
+note: required by a bound in `with_closure_expecting_fn_with_free_region`
+  --> $DIR/expect-fn-supply-fn.rs:7:8
+   |
+LL | fn with_closure_expecting_fn_with_free_region<F>(_: F)
+   |    ------------------------------------------ required by a bound in this
+LL | where
+LL |     F: for<'a> FnOnce(fn(&'a u32), &i32),
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `with_closure_expecting_fn_with_free_region`
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:45:53
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:43:5
    |
 LL |     with_closure_expecting_fn_with_bound_region(|x: fn(&'x u32), y| {});
-   |                                                     ^^^^^^^^^^^ one type is more general than the other
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ------------------- found signature of `fn(fn(&'x u32), _) -> _`
+   |     |
+   |     expected signature of `for<'r> fn(for<'s> fn(&'s u32), &'r i32) -> _`
    |
-   = note: expected fn pointer `for<'r> fn(&'r u32)`
-              found fn pointer `fn(&'x u32)`
+note: required by a bound in `with_closure_expecting_fn_with_bound_region`
+  --> $DIR/expect-fn-supply-fn.rs:13:8
+   |
+LL | fn with_closure_expecting_fn_with_bound_region<F>(_: F)
+   |    ------------------------------------------- required by a bound in this
+LL | where
+LL |     F: FnOnce(fn(&u32), &i32),
+   |        ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `with_closure_expecting_fn_with_bound_region`
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:54:53
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:52:5
    |
 LL |     with_closure_expecting_fn_with_bound_region(|x: Foo<'_>, y| {
-   |                                                     ^^^^^^^ one type is more general than the other
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ --------------- found signature of `for<'r> fn(for<'r> fn(&'r u32), _) -> _`
+   |     |
+   |     expected signature of `for<'r> fn(for<'s> fn(&'s u32), &'r i32) -> _`
+   |
+note: required by a bound in `with_closure_expecting_fn_with_bound_region`
+  --> $DIR/expect-fn-supply-fn.rs:13:8
    |
-   = note: expected fn pointer `for<'r> fn(&'r u32)`
-              found fn pointer `fn(&u32)`
+LL | fn with_closure_expecting_fn_with_bound_region<F>(_: F)
+   |    ------------------------------------------- required by a bound in this
+LL | where
+LL |     F: FnOnce(fn(&u32), &i32),
+   |        ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `with_closure_expecting_fn_with_bound_region`
 
 error: aborting due to 5 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+Some errors have detailed explanations: E0308, E0631.
+For more information about an error, try `rustc --explain E0308`.

src/test/ui/closure-expected-type/expect-fn-supply-fn.nll.stderr

@@ -1,51 +1,54 @@
-error: lifetime may not live long enough
-  --> $DIR/expect-fn-supply-fn.rs:20:49
-   |
-LL | fn expect_free_supply_free_from_fn<'x>(x: &'x u32) {
-   |                                    -- lifetime `'x` defined here
-...
-LL |     with_closure_expecting_fn_with_free_region(|x: fn(&'x u32), y| {});
-   |                                                 ^
-   |                                                 |
-   |                                                 has type `fn(&'1 u32)`
-   |                                                 requires that `'1` must outlive `'x`
-
-error: lifetime may not live long enough
-  --> $DIR/expect-fn-supply-fn.rs:20:49
-   |
-LL | fn expect_free_supply_free_from_fn<'x>(x: &'x u32) {
-   |                                    -- lifetime `'x` defined here
-...
-LL |     with_closure_expecting_fn_with_free_region(|x: fn(&'x u32), y| {});
-   |                                                 ^ requires that `'x` must outlive `'static`
-
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:38:49
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:36:5
    |
 LL |     with_closure_expecting_fn_with_free_region(|x: fn(&u32), y| {});
-   |                                                 ^ one type is more general than the other
-   |
-   = note: expected fn pointer `for<'r> fn(&'r u32)`
-              found fn pointer `fn(&u32)`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ---------------- found signature of `fn(for<'r> fn(&'r u32), _) -> _`
+   |     |
+   |     expected signature of `for<'a, 'r> fn(for<'a> fn(&'a u32), &'r i32) -> _`
+   |
+note: required by a bound in `with_closure_expecting_fn_with_free_region`
+  --> $DIR/expect-fn-supply-fn.rs:7:8
+   |
+LL | fn with_closure_expecting_fn_with_free_region<F>(_: F)
+   |    ------------------------------------------ required by a bound in this
+LL | where
+LL |     F: for<'a> FnOnce(fn(&'a u32), &i32),
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `with_closure_expecting_fn_with_free_region`
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:45:50
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:43:5
    |
 LL |     with_closure_expecting_fn_with_bound_region(|x: fn(&'x u32), y| {});
-   |                                                  ^ one type is more general than the other
-   |
-   = note: expected fn pointer `fn(&'x u32)`
-              found fn pointer `for<'r> fn(&'r u32)`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ------------------- found signature of `fn(fn(&'x u32), _) -> _`
+   |     |
+   |     expected signature of `for<'r> fn(for<'s> fn(&'s u32), &'r i32) -> _`
+   |
+note: required by a bound in `with_closure_expecting_fn_with_bound_region`
+  --> $DIR/expect-fn-supply-fn.rs:13:8
+   |
+LL | fn with_closure_expecting_fn_with_bound_region<F>(_: F)
+   |    ------------------------------------------- required by a bound in this
+LL | where
+LL |     F: FnOnce(fn(&u32), &i32),
+   |        ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `with_closure_expecting_fn_with_bound_region`
 
-error[E0308]: mismatched types
-  --> $DIR/expect-fn-supply-fn.rs:54:50
+error[E0631]: type mismatch in closure arguments
+  --> $DIR/expect-fn-supply-fn.rs:52:5
    |
 LL |     with_closure_expecting_fn_with_bound_region(|x: Foo<'_>, y| {
-   |                                                  ^ one type is more general than the other
-   |
-   = note: expected fn pointer `fn(&u32)`
-              found fn pointer `for<'r> fn(&'r u32)`
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ --------------- found signature of `for<'r> fn(for<'r> fn(&'r u32), _) -> _`
+   |     |
+   |     expected signature of `for<'r> fn(for<'s> fn(&'s u32), &'r i32) -> _`
+   |
+note: required by a bound in `with_closure_expecting_fn_with_bound_region`
+  --> $DIR/expect-fn-supply-fn.rs:13:8
+   |
+LL | fn with_closure_expecting_fn_with_bound_region<F>(_: F)
+   |    ------------------------------------------- required by a bound in this
+LL | where
+LL |     F: FnOnce(fn(&u32), &i32),
+   |        ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `with_closure_expecting_fn_with_bound_region`
 
-error: aborting due to 5 previous errors
+error: aborting due to 3 previous errors
 
-For more information about this error, try `rustc --explain E0308`.
+For more information about this error, try `rustc --explain E0631`.

src/test/ui/closure-expected-type/expect-fn-supply-fn.rs

@@ -20,8 +20,6 @@ fn expect_free_supply_free_from_fn<'x>(x: &'x u32) {
     with_closure_expecting_fn_with_free_region(|x: fn(&'x u32), y| {});
     //[base]~^ ERROR mismatched types
     //[base]~| ERROR mismatched types
-    //[nll]~^^^ ERROR lifetime may not live long enough
-    //[nll]~| ERROR lifetime may not live long enough
 }
 
 fn expect_free_supply_free_from_closure() {
@@ -36,14 +34,14 @@ fn expect_free_supply_bound() {
     // Here, we are given a function whose region is bound at closure level,
     // but we expect one bound in the argument. Error results.
     with_closure_expecting_fn_with_free_region(|x: fn(&u32), y| {});
-    //~^ ERROR mismatched types
+    //~^ ERROR type mismatch in closure arguments
 }
 
 fn expect_bound_supply_free_from_fn<'x>(x: &'x u32) {
     // Here, we are given a `fn(&u32)` but we expect a `fn(&'x
     // u32)`. In principle, this could be ok, but we demand equality.
     with_closure_expecting_fn_with_bound_region(|x: fn(&'x u32), y| {});
-    //~^ ERROR mismatched types
+    //~^ ERROR type mismatch in closure arguments
 }
 
 fn expect_bound_supply_free_from_closure() {
@@ -52,7 +50,7 @@ fn expect_bound_supply_free_from_closure() {
     // the argument level.
     type Foo<'a> = fn(&'a u32);
     with_closure_expecting_fn_with_bound_region(|x: Foo<'_>, y| {
-        //~^ ERROR mismatched types
+        //~^ ERROR type mismatch in closure arguments
     });
 }
 

src/test/ui/coherence/coherence-fn-covariant-bound-vs-static.rs

@@ -10,12 +10,14 @@
 //   * true if `exists<'r> { 'r: 'static }` (obviously true)
 // * `fn(fn(&'static u32)) <: for<'r> fn(fn(&'r u32))`
 //   * true if `forall<'r> { 'static: 'r }` (also true)
+//
+// check-pass
+
 
 trait Trait {}
 
 impl Trait for for<'r> fn(fn(&'r ())) {}
 impl<'a> Trait for fn(fn(&'a ())) {}
-//~^ ERROR conflicting implementations
 //
 // Note in particular that we do NOT get a future-compatibility warning
 // here. This is because the new leak-check proposed in [MCP 295] does not

src/test/ui/coherence/coherence-fn-implied-bounds.rs

@@ -11,16 +11,12 @@
 // Note that while we would like to make this a hard error, we also
 // give the same warning for `coherence-wasm-bindgen.rs`, which ought
 // to be accepted.
-
-#![deny(coherence_leak_check)]
-
+//
+// check-pass
 trait Trait {}
 
 impl Trait for for<'a, 'b> fn(&'a &'b u32, &'b &'a u32) -> &'b u32 {}
 
-impl Trait for for<'c> fn(&'c &'c u32, &'c &'c u32) -> &'c u32 {
-    //~^ ERROR conflicting implementations
-    //~| WARNING this was previously accepted by the compiler
-}
+impl Trait for for<'c> fn(&'c &'c u32, &'c &'c u32) -> &'c u32 {}
 
 fn main() {}