Point at appropriate type parameter in more trait bound errors

18 files changed, 85 insertions, 58 deletions

diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
index f6a5b8f97a1..f50aeaf4511 100644
--- a/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
+++ b/compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
@@ -67,6 +67,37 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             })
         };
 
+        // Account for enum variant constructors, where the type param corresponds to the enum
+        // itself.
+        let enum_def_id = if let hir::def::DefKind::Ctor(hir::def::CtorOf::Variant, _) =
+            self.tcx.def_kind(def_id)
+        {
+            // `def_id` corresponds to a constructor, and its parent is the variant, and we want
+            // the enum.
+            Some(self.tcx.parent(self.tcx.parent(def_id)))
+        } else {
+            None
+        };
+        let variant_param_to_point_at = find_param_matching(&|param_term| {
+            // FIXME: It would be nice to make this not use string manipulation,
+            // but it's pretty hard to do this, since `ty::ParamTy` is missing
+            // sufficient info to determine if it is synthetic, and we don't
+            // always have a convenient way of getting `ty::Generics` at the call
+            // sites we invoke `IsSuggestable::is_suggestable`.
+            let include = match param_term {
+                ty::ParamTerm::Ty(param_ty) => !param_ty.name.as_str().starts_with("impl "),
+                _ => true,
+            };
+            // Account for enum variant constructors, where the type param corresponds to the enum
+            // itself.
+            let def_id = if let Some(def_id) = enum_def_id {
+                def_id
+            } else {
+                def_id
+            };
+            self.tcx.parent(generics.param_at(param_term.index(), self.tcx).def_id) == def_id
+                && include
+        });
         // Prefer generics that are local to the fn item, since these are likely
         // to be the cause of the unsatisfied predicate.
         let mut param_to_point_at = find_param_matching(&|param_term| {
@@ -102,6 +133,20 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         match &expr.kind {
             hir::ExprKind::Path(qpath) => {
+                let def_id = if let Some(def_id) = enum_def_id {
+                    def_id
+                } else {
+                    def_id
+                };
+                if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind {
+                    for segment in path.segments {
+                        if let Some(param) = variant_param_to_point_at
+                            && self.point_at_generic_if_possible(error, def_id, param, segment)
+                        {
+                            return true;
+                        }
+                    }
+                }
                 if let hir::Node::Expr(hir::Expr {
                     kind: hir::ExprKind::Call(callee, args),
                     hir_id: call_hir_id,
diff --git a/tests/ui/associated-types/associated-types-issue-20346.stderr b/tests/ui/associated-types/associated-types-issue-20346.stderr
index b1708b96e52..d8b0433d3e8 100644
--- a/tests/ui/associated-types/associated-types-issue-20346.stderr
+++ b/tests/ui/associated-types/associated-types-issue-20346.stderr
@@ -1,13 +1,11 @@
 error[E0271]: type mismatch resolving `<Adapter<I> as Iterator>::Item == Option<T>`
-  --> $DIR/associated-types-issue-20346.rs:34:36
+  --> $DIR/associated-types-issue-20346.rs:34:33
    |
 LL | fn test_adapter<T, I: Iterator<Item=Option<T>>>(it: I) {
    |                 - this type parameter
 ...
 LL |     is_iterator_of::<Option<T>, _>(&adapter);
-   |     ------------------------------ ^^^^^^^^ type mismatch resolving `<Adapter<I> as Iterator>::Item == Option<T>`
-   |     |
-   |     required by a bound introduced by this call
+   |                                 ^ type mismatch resolving `<Adapter<I> as Iterator>::Item == Option<T>`
    |
 note: expected this to be `Option<T>`
   --> $DIR/associated-types-issue-20346.rs:23:17
diff --git a/tests/ui/function-pointer/unsized-ret.stderr b/tests/ui/function-pointer/unsized-ret.stderr
index 870f1805b58..dcfec53eeb9 100644
--- a/tests/ui/function-pointer/unsized-ret.stderr
+++ b/tests/ui/function-pointer/unsized-ret.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the size for values of type `str` cannot be known at compilation time
-  --> $DIR/unsized-ret.rs:10:27
+  --> $DIR/unsized-ret.rs:10:11
    |
 LL |     foo::<fn() -> str, _>(None, ());
-   |     --------------------- ^^^^ doesn't have a size known at compile-time
-   |     |
-   |     required by a bound introduced by this call
+   |           ^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: within `fn() -> str`, the trait `Sized` is not implemented for `str`
    = note: required because it appears within the type `fn() -> str`
@@ -15,12 +13,10 @@ LL | fn foo<F: Fn<T>, T:std::marker::Tuple>(f: Option<F>, t: T) {
    |           ^^^^^ required by this bound in `foo`
 
 error[E0277]: the size for values of type `(dyn std::fmt::Display + 'a)` cannot be known at compilation time
-  --> $DIR/unsized-ret.rs:13:66
+  --> $DIR/unsized-ret.rs:13:11
    |
 LL |     foo::<for<'a> fn(&'a ()) -> (dyn std::fmt::Display + 'a), _>(None, (&(),));
-   |     ------------------------------------------------------------ ^^^^ doesn't have a size known at compile-time
-   |     |
-   |     required by a bound introduced by this call
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
    |
    = help: within `for<'a> fn(&'a ()) -> (dyn std::fmt::Display + 'a)`, the trait `for<'a> Sized` is not implemented for `(dyn std::fmt::Display + 'a)`
    = note: required because it appears within the type `fn(&()) -> dyn Display`
diff --git a/tests/ui/issues/issue-87199.stderr b/tests/ui/issues/issue-87199.stderr
index 0ec5e73f39a..67949b37d40 100644
--- a/tests/ui/issues/issue-87199.stderr
+++ b/tests/ui/issues/issue-87199.stderr
@@ -17,12 +17,10 @@ LL | fn ret() -> impl Iterator<Item = ()> + ?Send { std::iter::empty() }
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error[E0277]: the size for values of type `[i32]` cannot be known at compilation time
-  --> $DIR/issue-87199.rs:18:22
+  --> $DIR/issue-87199.rs:18:15
    |
 LL |     ref_arg::<[i32]>(&[5]);
-   |     ---------------- ^^^^ doesn't have a size known at compile-time
-   |     |
-   |     required by a bound introduced by this call
+   |               ^^^^^ doesn't have a size known at compile-time
    |
    = help: the trait `Sized` is not implemented for `[i32]`
 note: required by a bound in `ref_arg`
diff --git a/tests/ui/suggestions/imm-ref-trait-object-literal-bound-regions.stderr b/tests/ui/suggestions/imm-ref-trait-object-literal-bound-regions.stderr
index fc5a521746a..11f94c604a1 100644
--- a/tests/ui/suggestions/imm-ref-trait-object-literal-bound-regions.stderr
+++ b/tests/ui/suggestions/imm-ref-trait-object-literal-bound-regions.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `for<'b> &'b S: Trait` is not satisfied
-  --> $DIR/imm-ref-trait-object-literal-bound-regions.rs:17:14
+  --> $DIR/imm-ref-trait-object-literal-bound-regions.rs:17:11
    |
 LL |     foo::<S>(s);
-   |     -------- ^ the trait `for<'b> Trait` is not implemented for `&'b S`
-   |     |
-   |     required by a bound introduced by this call
+   |           ^ the trait `for<'b> Trait` is not implemented for `&'b S`
    |
    = help: the trait `Trait` is implemented for `&'a mut S`
    = note: `for<'b> Trait` is implemented for `&'b mut S`, but not for `&'b S`
diff --git a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr b/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr
index f7551739b13..4eaa259617b 100644
--- a/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr
+++ b/tests/ui/traits/new-solver/builtin-fn-must-return-sized.stderr
@@ -1,10 +1,8 @@
 error[E0277]: expected a `Fn<_>` closure, found `fn() -> str`
-  --> $DIR/builtin-fn-must-return-sized.rs:15:27
+  --> $DIR/builtin-fn-must-return-sized.rs:15:11
    |
 LL |     foo::<fn() -> str, _>(None, ());
-   |     --------------------- ^^^^ expected an `Fn<_>` closure, found `fn() -> str`
-   |     |
-   |     required by a bound introduced by this call
+   |           ^^^^^^^^^^^ expected an `Fn<_>` closure, found `fn() -> str`
    |
    = help: the trait `Fn<_>` is not implemented for `fn() -> str`
 note: required by a bound in `foo`
diff --git a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr b/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
index 7d3535e1f01..a861156711d 100644
--- a/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
+++ b/tests/ui/traits/new-solver/cycles/coinduction/fixpoint-exponential-growth.stderr
@@ -5,10 +5,10 @@ LL |     impls::<W<_>>();
    |     ^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `impls`
 
 error[E0275]: overflow evaluating the requirement `W<_>: Trait`
-  --> $DIR/fixpoint-exponential-growth.rs:29:5
+  --> $DIR/fixpoint-exponential-growth.rs:29:13
    |
 LL |     impls::<W<_>>();
-   |     ^^^^^^^^^^^^^
+   |             ^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`fixpoint_exponential_growth`)
 note: required by a bound in `impls`
diff --git a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr b/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
index 4b8846da535..a3404da51f0 100644
--- a/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
+++ b/tests/ui/traits/new-solver/cycles/double-cycle-inductive-coinductive.stderr
@@ -1,8 +1,8 @@
 error[E0275]: overflow evaluating the requirement `(): Trait`
-  --> $DIR/double-cycle-inductive-coinductive.rs:32:5
+  --> $DIR/double-cycle-inductive-coinductive.rs:32:19
    |
 LL |     impls_trait::<()>();
-   |     ^^^^^^^^^^^^^^^^^
+   |                   ^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`double_cycle_inductive_coinductive`)
 note: required by a bound in `impls_trait`
@@ -12,10 +12,10 @@ LL | fn impls_trait<T: Trait>() {}
    |                   ^^^^^ required by this bound in `impls_trait`
 
 error[E0275]: overflow evaluating the requirement `(): TraitRev`
-  --> $DIR/double-cycle-inductive-coinductive.rs:35:5
+  --> $DIR/double-cycle-inductive-coinductive.rs:35:23
    |
 LL |     impls_trait_rev::<()>();
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |                       ^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`double_cycle_inductive_coinductive`)
 note: required by a bound in `impls_trait_rev`
diff --git a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
index 0e1c86c1bb3..34115334063 100644
--- a/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
+++ b/tests/ui/traits/new-solver/cycles/inductive-not-on-stack.stderr
@@ -1,8 +1,8 @@
 error[E0275]: overflow evaluating the requirement `(): AR`
-  --> $DIR/inductive-not-on-stack.rs:44:5
+  --> $DIR/inductive-not-on-stack.rs:44:16
    |
 LL |     impls_ar::<()>();
-   |     ^^^^^^^^^^^^^^
+   |                ^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`inductive_not_on_stack`)
 note: required by a bound in `impls_ar`
diff --git a/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.not_send.stderr b/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
index ec1c3231abc..a31bfd9589b 100644
--- a/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
+++ b/tests/ui/traits/new-solver/dont-type_of-tait-in-defining-scope.not_send.stderr
@@ -1,8 +1,8 @@
 error[E0283]: type annotations needed: cannot satisfy `Foo: Send`
-  --> $DIR/dont-type_of-tait-in-defining-scope.rs:16:5
+  --> $DIR/dont-type_of-tait-in-defining-scope.rs:16:18
    |
 LL |     needs_send::<Foo>();
-   |     ^^^^^^^^^^^^^^^^^
+   |                  ^^^
    |
    = note: cannot satisfy `Foo: Send`
 note: required by a bound in `needs_send`
diff --git a/tests/ui/traits/new-solver/overflow/exponential-trait-goals.stderr b/tests/ui/traits/new-solver/overflow/exponential-trait-goals.stderr
index 28a99cbbca6..beed40f3649 100644
--- a/tests/ui/traits/new-solver/overflow/exponential-trait-goals.stderr
+++ b/tests/ui/traits/new-solver/overflow/exponential-trait-goals.stderr
@@ -5,10 +5,10 @@ LL |     impls::<W<_>>();
    |     ^^^^^^^^^^^^^ cannot infer type of the type parameter `T` declared on the function `impls`
 
 error[E0275]: overflow evaluating the requirement `W<_>: Trait`
-  --> $DIR/exponential-trait-goals.rs:17:5
+  --> $DIR/exponential-trait-goals.rs:17:13
    |
 LL |     impls::<W<_>>();
-   |     ^^^^^^^^^^^^^
+   |             ^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`exponential_trait_goals`)
 note: required by a bound in `impls`
diff --git a/tests/ui/traits/new-solver/overflow/global-cache.stderr b/tests/ui/traits/new-solver/overflow/global-cache.stderr
index f3b86a083ad..ebb03d84b87 100644
--- a/tests/ui/traits/new-solver/overflow/global-cache.stderr
+++ b/tests/ui/traits/new-solver/overflow/global-cache.stderr
@@ -1,8 +1,8 @@
 error[E0275]: overflow evaluating the requirement `Inc<Inc<Inc<Inc<Inc<Inc<Inc<...>>>>>>>: Trait`
-  --> $DIR/global-cache.rs:21:5
+  --> $DIR/global-cache.rs:21:19
    |
 LL |     impls_trait::<Four<Four<Four<Four<()>>>>>();
-   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "18"]` attribute to your crate (`global_cache`)
 note: required by a bound in `impls_trait`
diff --git a/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.stderr b/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.stderr
index eebaf21d7df..1dc63fae98c 100644
--- a/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.stderr
+++ b/tests/ui/traits/new-solver/overflow/recursive-self-normalization-2.stderr
@@ -1,8 +1,8 @@
 error[E0275]: overflow evaluating the requirement `<T as Foo1>::Assoc1: Bar`
-  --> $DIR/recursive-self-normalization-2.rs:16:5
+  --> $DIR/recursive-self-normalization-2.rs:16:17
    |
 LL |     needs_bar::<T::Assoc1>();
-   |     ^^^^^^^^^^^^^^^^^^^^^^
+   |                 ^^^^^^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`recursive_self_normalization_2`)
 note: required by a bound in `needs_bar`
diff --git a/tests/ui/traits/new-solver/overflow/recursive-self-normalization.stderr b/tests/ui/traits/new-solver/overflow/recursive-self-normalization.stderr
index 6a87fe2f121..afc5bfa54ac 100644
--- a/tests/ui/traits/new-solver/overflow/recursive-self-normalization.stderr
+++ b/tests/ui/traits/new-solver/overflow/recursive-self-normalization.stderr
@@ -1,8 +1,8 @@
 error[E0275]: overflow evaluating the requirement `<T as Foo>::Assoc: Bar`
-  --> $DIR/recursive-self-normalization.rs:12:5
+  --> $DIR/recursive-self-normalization.rs:12:17
    |
 LL |     needs_bar::<T::Assoc>();
-   |     ^^^^^^^^^^^^^^^^^^^^^
+   |                 ^^^^^^^^
    |
    = help: consider increasing the recursion limit by adding a `#![recursion_limit = "256"]` attribute to your crate (`recursive_self_normalization`)
 note: required by a bound in `needs_bar`
diff --git a/tests/ui/traits/new-solver/specialization-unconstrained.stderr b/tests/ui/traits/new-solver/specialization-unconstrained.stderr
index 9915da1a27a..ff0440d51ad 100644
--- a/tests/ui/traits/new-solver/specialization-unconstrained.stderr
+++ b/tests/ui/traits/new-solver/specialization-unconstrained.stderr
@@ -15,10 +15,10 @@ LL |    default type Id = T;
    |                      ^ cannot infer type for associated type `<T as Default>::Id`
 
 error[E0284]: type annotations needed: cannot satisfy `<u32 as Default>::Id == ()`
-  --> $DIR/specialization-unconstrained.rs:20:5
+  --> $DIR/specialization-unconstrained.rs:20:12
    |
 LL |     test::<u32, ()>();
-   |     ^^^^^^^^^^^^^^^ cannot satisfy `<u32 as Default>::Id == ()`
+   |            ^^^ cannot satisfy `<u32 as Default>::Id == ()`
    |
 note: required by a bound in `test`
   --> $DIR/specialization-unconstrained.rs:17:20
diff --git a/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.stderr b/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.stderr
index 83a0452b088..b311ac6b5a6 100644
--- a/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.stderr
+++ b/tests/ui/traits/new-solver/two-projection-param-candidates-are-ambiguous.stderr
@@ -1,8 +1,8 @@
 error[E0283]: type annotations needed: cannot satisfy `T: Bar`
-  --> $DIR/two-projection-param-candidates-are-ambiguous.rs:26:5
+  --> $DIR/two-projection-param-candidates-are-ambiguous.rs:26:17
    |
 LL |     needs_bar::<T>();
-   |     ^^^^^^^^^^^^^^
+   |                 ^
    |
    = note: cannot satisfy `T: Bar`
    = help: the trait `Bar` is implemented for `T`
diff --git a/tests/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr b/tests/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr
index 08eab025370..a75024aa248 100644
--- a/tests/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr
+++ b/tests/ui/typeck/issue-90804-incorrect-reference-suggestion.stderr
@@ -1,10 +1,8 @@
 error[E0277]: the trait bound `(): Marker<u32>` is not satisfied
-  --> $DIR/issue-90804-incorrect-reference-suggestion.rs:10:17
+  --> $DIR/issue-90804-incorrect-reference-suggestion.rs:10:13
    |
 LL |     check::<()>(());
-   |     ----------- ^^ the trait `Marker<u32>` is not implemented for `()`
-   |     |
-   |     required by a bound introduced by this call
+   |             ^^ the trait `Marker<u32>` is not implemented for `()`
    |
 note: required by a bound in `check`
   --> $DIR/issue-90804-incorrect-reference-suggestion.rs:7:17
diff --git a/tests/ui/unsized/unsized3.stderr b/tests/ui/unsized/unsized3.stderr
index 3ef9a875358..a11243980d1 100644
--- a/tests/ui/unsized/unsized3.stderr
+++ b/tests/ui/unsized/unsized3.stderr
@@ -1,12 +1,10 @@
 error[E0277]: the size for values of type `X` cannot be known at compilation time
-  --> $DIR/unsized3.rs:7:13
+  --> $DIR/unsized3.rs:7:10
    |
 LL | fn f1<X: ?Sized>(x: &X) {
    |       - this type parameter needs to be `Sized`
 LL |     f2::<X>(x);
-   |     ------- ^ doesn't have a size known at compile-time
-   |     |
-   |     required by a bound introduced by this call
+   |          ^ doesn't have a size known at compile-time
    |
 note: required by a bound in `f2`
   --> $DIR/unsized3.rs:10:7
@@ -24,14 +22,12 @@ LL | fn f2<X: ?Sized>(x: &X) {
    |        ++++++++
 
 error[E0277]: the size for values of type `X` cannot be known at compilation time
-  --> $DIR/unsized3.rs:18:13
+  --> $DIR/unsized3.rs:18:10
    |
 LL | fn f3<X: ?Sized + T>(x: &X) {
    |       - this type parameter needs to be `Sized`
 LL |     f4::<X>(x);
-   |     ------- ^ doesn't have a size known at compile-time
-   |     |
-   |     required by a bound introduced by this call
+   |          ^ doesn't have a size known at compile-time
    |
 note: required by a bound in `f4`
   --> $DIR/unsized3.rs:21:7