diff --git a/compiler/rustc_hir_analysis/src/impl_wf_check.rs b/compiler/rustc_hir_analysis/src/impl_wf_check.rs
index 8ab9964d81000..9f98923275435 100644
--- a/compiler/rustc_hir_analysis/src/impl_wf_check.rs
+++ b/compiler/rustc_hir_analysis/src/impl_wf_check.rs
@@ -12,7 +12,7 @@ use crate::constrained_generic_params as cgp;
 use min_specialization::check_min_specialization;
 
 use rustc_data_structures::fx::FxHashSet;
-use rustc_errors::struct_span_err;
+use rustc_errors::{struct_span_err, Applicability};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::ty::query::Providers;
@@ -181,6 +181,15 @@ fn report_unused_parameter(tcx: TyCtxt<'_>, span: Span, kind: &str, name: Symbol
         name
     );
     err.span_label(span, format!("unconstrained {} parameter", kind));
+    err.span_suggestion(
+        span,
+        format!(
+            "Either remove the type parameter '{}' or make use of it, for example ` for S<{}>`.",
+            name, name
+        ),
+        "",
+        Applicability::MaybeIncorrect,
+    );
     if kind == "const" {
         err.note(
             "expressions using a const parameter must map each value to a distinct output value",
diff --git a/tests/ui/async-await/issues/issue-78654.full.stderr b/tests/ui/async-await/issues/issue-78654.full.stderr
index 0d12a948c68bd..9291b8be7084e 100644
--- a/tests/ui/async-await/issues/issue-78654.full.stderr
+++ b/tests/ui/async-await/issues/issue-78654.full.stderr
@@ -12,6 +12,11 @@ LL | impl<const H: feature> Foo {
    |
    = note: expressions using a const parameter must map each value to a distinct output value
    = note: proving the result of expressions other than the parameter are unique is not supported
+help: Either remove the type parameter 'H' or make use of it, for example ` for S<H>`.
+   |
+LL - impl<const H: feature> Foo {
+LL + impl<> Foo {
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/async-await/issues/issue-78654.min.stderr b/tests/ui/async-await/issues/issue-78654.min.stderr
index 0d12a948c68bd..9291b8be7084e 100644
--- a/tests/ui/async-await/issues/issue-78654.min.stderr
+++ b/tests/ui/async-await/issues/issue-78654.min.stderr
@@ -12,6 +12,11 @@ LL | impl<const H: feature> Foo {
    |
    = note: expressions using a const parameter must map each value to a distinct output value
    = note: proving the result of expressions other than the parameter are unique is not supported
+help: Either remove the type parameter 'H' or make use of it, for example ` for S<H>`.
+   |
+LL - impl<const H: feature> Foo {
+LL + impl<> Foo {
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/const-generics/issues/issue-68366.full.stderr b/tests/ui/const-generics/issues/issue-68366.full.stderr
index ca9eb801dfce7..7019bac8d903a 100644
--- a/tests/ui/const-generics/issues/issue-68366.full.stderr
+++ b/tests/ui/const-generics/issues/issue-68366.full.stderr
@@ -6,6 +6,11 @@ LL | impl <const N: usize> Collatz<{Some(N)}> {}
    |
    = note: expressions using a const parameter must map each value to a distinct output value
    = note: proving the result of expressions other than the parameter are unique is not supported
+help: Either remove the type parameter 'N' or make use of it, for example ` for S<N>`.
+   |
+LL - impl <const N: usize> Collatz<{Some(N)}> {}
+LL + impl <> Collatz<{Some(N)}> {}
+   |
 
 error[E0207]: the const parameter `N` is not constrained by the impl trait, self type, or predicates
   --> $DIR/issue-68366.rs:17:6
@@ -15,6 +20,11 @@ LL | impl<const N: usize> Foo {}
    |
    = note: expressions using a const parameter must map each value to a distinct output value
    = note: proving the result of expressions other than the parameter are unique is not supported
+help: Either remove the type parameter 'N' or make use of it, for example ` for S<N>`.
+   |
+LL - impl<const N: usize> Foo {}
+LL + impl<> Foo {}
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/const-generics/issues/issue-68366.min.stderr b/tests/ui/const-generics/issues/issue-68366.min.stderr
index 3740ced90b1d7..e9d07a7d86673 100644
--- a/tests/ui/const-generics/issues/issue-68366.min.stderr
+++ b/tests/ui/const-generics/issues/issue-68366.min.stderr
@@ -15,6 +15,11 @@ LL | impl <const N: usize> Collatz<{Some(N)}> {}
    |
    = note: expressions using a const parameter must map each value to a distinct output value
    = note: proving the result of expressions other than the parameter are unique is not supported
+help: Either remove the type parameter 'N' or make use of it, for example ` for S<N>`.
+   |
+LL - impl <const N: usize> Collatz<{Some(N)}> {}
+LL + impl <> Collatz<{Some(N)}> {}
+   |
 
 error[E0207]: the const parameter `N` is not constrained by the impl trait, self type, or predicates
   --> $DIR/issue-68366.rs:17:6
@@ -24,6 +29,11 @@ LL | impl<const N: usize> Foo {}
    |
    = note: expressions using a const parameter must map each value to a distinct output value
    = note: proving the result of expressions other than the parameter are unique is not supported
+help: Either remove the type parameter 'N' or make use of it, for example ` for S<N>`.
+   |
+LL - impl<const N: usize> Foo {}
+LL + impl<> Foo {}
+   |
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/duplicate/duplicate-type-parameter.stderr b/tests/ui/duplicate/duplicate-type-parameter.stderr
index 628f898d5c879..a9554b7479e83 100644
--- a/tests/ui/duplicate/duplicate-type-parameter.stderr
+++ b/tests/ui/duplicate/duplicate-type-parameter.stderr
@@ -59,6 +59,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T,T> Qux<T,T> for Option<T> {}
    |        ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T,T> Qux<T,T> for Option<T> {}
+LL + impl<T,> Qux<T,T> for Option<T> {}
+   |
 
 error: aborting due to 8 previous errors
 
diff --git a/tests/ui/error-codes/E0207.stderr b/tests/ui/error-codes/E0207.stderr
index 5ef51ed86926a..a4a24ed2be64c 100644
--- a/tests/ui/error-codes/E0207.stderr
+++ b/tests/ui/error-codes/E0207.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T: Default> Foo {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T: Default> Foo {
+LL + impl<: Default> Foo {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/generic-associated-types/bugs/issue-87735.stderr b/tests/ui/generic-associated-types/bugs/issue-87735.stderr
index ebe2054ce5efc..9f136b653c050 100644
--- a/tests/ui/generic-associated-types/bugs/issue-87735.stderr
+++ b/tests/ui/generic-associated-types/bugs/issue-87735.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `U` is not constrained by the impl trait, self
    |
 LL | impl<'b, T, U> AsRef2 for Foo<T>
    |             ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'U' or make use of it, for example ` for S<U>`.
+   |
+LL - impl<'b, T, U> AsRef2 for Foo<T>
+LL + impl<'b, T, > AsRef2 for Foo<T>
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/generic-associated-types/bugs/issue-88526.stderr b/tests/ui/generic-associated-types/bugs/issue-88526.stderr
index 56857c6550bdc..07534fae48498 100644
--- a/tests/ui/generic-associated-types/bugs/issue-88526.stderr
+++ b/tests/ui/generic-associated-types/bugs/issue-88526.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `I` is not constrained by the impl trait, self
    |
 LL | impl<'q, Q, I, F> A for TestB<Q, F>
    |             ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'I' or make use of it, for example ` for S<I>`.
+   |
+LL - impl<'q, Q, I, F> A for TestB<Q, F>
+LL + impl<'q, Q, , F> A for TestB<Q, F>
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/generic-associated-types/gat-trait-path-generic-type-arg.stderr b/tests/ui/generic-associated-types/gat-trait-path-generic-type-arg.stderr
index cb2b9f32bfe72..103bce1ddf2a1 100644
--- a/tests/ui/generic-associated-types/gat-trait-path-generic-type-arg.stderr
+++ b/tests/ui/generic-associated-types/gat-trait-path-generic-type-arg.stderr
@@ -18,6 +18,12 @@ error[E0207]: the type parameter `T1` is not constrained by the impl trait, self
    |
 LL | impl <T, T1> Foo for T {
    |          ^^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T1' or make use of it, for example ` for S<T1>`.
+   |
+LL - impl <T, T1> Foo for T {
+LL + impl <T, > Foo for T {
+   |
 
 error: aborting due to 3 previous errors
 
diff --git a/tests/ui/impl-trait/issues/issue-87340.stderr b/tests/ui/impl-trait/issues/issue-87340.stderr
index 2ab1e6a031248..3c82e3894ba19 100644
--- a/tests/ui/impl-trait/issues/issue-87340.stderr
+++ b/tests/ui/impl-trait/issues/issue-87340.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T> X for () {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T> X for () {
+LL + impl<> X for () {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/impl-unused-rps-in-assoc-type.stderr b/tests/ui/impl-unused-rps-in-assoc-type.stderr
index c7ad1b4e608fc..699658d76c4af 100644
--- a/tests/ui/impl-unused-rps-in-assoc-type.stderr
+++ b/tests/ui/impl-unused-rps-in-assoc-type.stderr
@@ -3,6 +3,12 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a> Fun for Holder {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a> Fun for Holder {
+LL + impl<> Fun for Holder {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/impl-unused-tps-inherent.stderr b/tests/ui/impl-unused-tps-inherent.stderr
index 43f63cf968cf5..a1b67617fc1fe 100644
--- a/tests/ui/impl-unused-tps-inherent.stderr
+++ b/tests/ui/impl-unused-tps-inherent.stderr
@@ -3,12 +3,24 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T> MyType {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T> MyType {
+LL + impl<> MyType {
+   |
 
 error[E0207]: the type parameter `U` is not constrained by the impl trait, self type, or predicates
   --> $DIR/impl-unused-tps-inherent.rs:17:8
    |
 LL | impl<T,U> MyType1<T> {
    |        ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'U' or make use of it, for example ` for S<U>`.
+   |
+LL - impl<T,U> MyType1<T> {
+LL + impl<T,> MyType1<T> {
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/impl-unused-tps.stderr b/tests/ui/impl-unused-tps.stderr
index 053ab91c89328..47b2c88c49308 100644
--- a/tests/ui/impl-unused-tps.stderr
+++ b/tests/ui/impl-unused-tps.stderr
@@ -3,30 +3,60 @@ error[E0207]: the type parameter `U` is not constrained by the impl trait, self
    |
 LL | impl<T,U> Foo<T> for [isize;1] {
    |        ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'U' or make use of it, for example ` for S<U>`.
+   |
+LL - impl<T,U> Foo<T> for [isize;1] {
+LL + impl<T,> Foo<T> for [isize;1] {
+   |
 
 error[E0207]: the type parameter `U` is not constrained by the impl trait, self type, or predicates
   --> $DIR/impl-unused-tps.rs:30:8
    |
 LL | impl<T,U> Bar for T {
    |        ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'U' or make use of it, for example ` for S<U>`.
+   |
+LL - impl<T,U> Bar for T {
+LL + impl<T,> Bar for T {
+   |
 
 error[E0207]: the type parameter `U` is not constrained by the impl trait, self type, or predicates
   --> $DIR/impl-unused-tps.rs:38:8
    |
 LL | impl<T,U> Bar for T
    |        ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'U' or make use of it, for example ` for S<U>`.
+   |
+LL - impl<T,U> Bar for T
+LL + impl<T,> Bar for T
+   |
 
 error[E0207]: the type parameter `U` is not constrained by the impl trait, self type, or predicates
   --> $DIR/impl-unused-tps.rs:46:8
    |
 LL | impl<T,U,V> Foo<T> for T
    |        ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'U' or make use of it, for example ` for S<U>`.
+   |
+LL - impl<T,U,V> Foo<T> for T
+LL + impl<T,,V> Foo<T> for T
+   |
 
 error[E0207]: the type parameter `V` is not constrained by the impl trait, self type, or predicates
   --> $DIR/impl-unused-tps.rs:46:10
    |
 LL | impl<T,U,V> Foo<T> for T
    |          ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'V' or make use of it, for example ` for S<V>`.
+   |
+LL - impl<T,U,V> Foo<T> for T
+LL + impl<T,U,> Foo<T> for T
+   |
 
 error: aborting due to 5 previous errors
 
diff --git a/tests/ui/issues/issue-16562.stderr b/tests/ui/issues/issue-16562.stderr
index 3fe7507e8a412..60385e06a52f2 100644
--- a/tests/ui/issues/issue-16562.stderr
+++ b/tests/ui/issues/issue-16562.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T, M: MatrixShape> Collection for Col<M, usize> {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T, M: MatrixShape> Collection for Col<M, usize> {
+LL + impl<, M: MatrixShape> Collection for Col<M, usize> {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/issues/issue-22886.stderr b/tests/ui/issues/issue-22886.stderr
index c4b3965592411..b05a9ca34709f 100644
--- a/tests/ui/issues/issue-22886.stderr
+++ b/tests/ui/issues/issue-22886.stderr
@@ -3,6 +3,12 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a> Iterator for Newtype {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a> Iterator for Newtype {
+LL + impl<> Iterator for Newtype {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/issues/issue-26262.stderr b/tests/ui/issues/issue-26262.stderr
index 90e2d0d930164..9b5f72a34f1f3 100644
--- a/tests/ui/issues/issue-26262.stderr
+++ b/tests/ui/issues/issue-26262.stderr
@@ -3,12 +3,24 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T: Tr> S<T::Assoc> {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T: Tr> S<T::Assoc> {
+LL + impl<: Tr> S<T::Assoc> {
+   |
 
 error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait, self type, or predicates
   --> $DIR/issue-26262.rs:17:6
    |
 LL | impl<'a,T: Trait2<'a>> Trait1<<T as Trait2<'a>>::Foo> for T {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a,T: Trait2<'a>> Trait1<<T as Trait2<'a>>::Foo> for T {
+LL + impl<,T: Trait2<'a>> Trait1<<T as Trait2<'a>>::Foo> for T {
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/issues/issue-29861.stderr b/tests/ui/issues/issue-29861.stderr
index d9d3cf360df2d..aa659e704c298 100644
--- a/tests/ui/issues/issue-29861.stderr
+++ b/tests/ui/issues/issue-29861.stderr
@@ -3,6 +3,12 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a, T: 'a> MakeRef2 for T {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a, T: 'a> MakeRef2 for T {
+LL + impl<, T: 'a> MakeRef2 for T {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/issues/issue-35139.stderr b/tests/ui/issues/issue-35139.stderr
index 79e889b7e599e..7de42fbd9a4c4 100644
--- a/tests/ui/issues/issue-35139.stderr
+++ b/tests/ui/issues/issue-35139.stderr
@@ -3,6 +3,12 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a> MethodType for MTFn {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a> MethodType for MTFn {
+LL + impl<> MethodType for MTFn {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr b/tests/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr
index e594dc577b1cd..464dc7062024e 100644
--- a/tests/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr
+++ b/tests/ui/type-alias-impl-trait/assoc-type-lifetime-unconstrained.stderr
@@ -3,6 +3,12 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a, I> UnwrapItemsExt for I {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a, I> UnwrapItemsExt for I {
+LL + impl<, I> UnwrapItemsExt for I {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr b/tests/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr
index 8cf8fb1d16c4d..980c440c6eabf 100644
--- a/tests/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr
+++ b/tests/ui/type-alias-impl-trait/impl-with-unconstrained-param.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T> X for () {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T> X for () {
+LL + impl<> X for () {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/type-alias-impl-trait/issue-74244.stderr b/tests/ui/type-alias-impl-trait/issue-74244.stderr
index ff6bacd277e1e..bdd1657eb1d4c 100644
--- a/tests/ui/type-alias-impl-trait/issue-74244.stderr
+++ b/tests/ui/type-alias-impl-trait/issue-74244.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<T> Allocator for DefaultAllocator {
    |      ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<T> Allocator for DefaultAllocator {
+LL + impl<> Allocator for DefaultAllocator {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/type-alias-impl-trait/issue-74761-2.stderr b/tests/ui/type-alias-impl-trait/issue-74761-2.stderr
index f15d0a069ca8a..253256d64d607 100644
--- a/tests/ui/type-alias-impl-trait/issue-74761-2.stderr
+++ b/tests/ui/type-alias-impl-trait/issue-74761-2.stderr
@@ -3,12 +3,24 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a, 'b> A for () {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a, 'b> A for () {
+LL + impl<, 'b> A for () {
+   |
 
 error[E0207]: the lifetime parameter `'b` is not constrained by the impl trait, self type, or predicates
   --> $DIR/issue-74761-2.rs:7:10
    |
 LL | impl<'a, 'b> A for () {
    |          ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''b' or make use of it, for example ` for S<'b>`.
+   |
+LL - impl<'a, 'b> A for () {
+LL + impl<'a, > A for () {
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/type-alias-impl-trait/issue-74761.stderr b/tests/ui/type-alias-impl-trait/issue-74761.stderr
index 1d016fe070f9c..e76aa8cfba362 100644
--- a/tests/ui/type-alias-impl-trait/issue-74761.stderr
+++ b/tests/ui/type-alias-impl-trait/issue-74761.stderr
@@ -3,12 +3,24 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a, 'b> A for () {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a, 'b> A for () {
+LL + impl<, 'b> A for () {
+   |
 
 error[E0207]: the lifetime parameter `'b` is not constrained by the impl trait, self type, or predicates
   --> $DIR/issue-74761.rs:7:10
    |
 LL | impl<'a, 'b> A for () {
    |          ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''b' or make use of it, for example ` for S<'b>`.
+   |
+LL - impl<'a, 'b> A for () {
+LL + impl<'a, > A for () {
+   |
 
 error: aborting due to 2 previous errors
 
diff --git a/tests/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr b/tests/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr
index 8cdce2f8e81ca..9bac0f9a336d2 100644
--- a/tests/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr
+++ b/tests/ui/type-alias-impl-trait/type-alias-impl-trait-unconstrained-lifetime.stderr
@@ -3,6 +3,12 @@ error[E0207]: the lifetime parameter `'a` is not constrained by the impl trait,
    |
 LL | impl<'a, I: Iterator<Item = i32>> Trait for (i32, I) {
    |      ^^ unconstrained lifetime parameter
+   |
+help: Either remove the type parameter ''a' or make use of it, for example ` for S<'a>`.
+   |
+LL - impl<'a, I: Iterator<Item = i32>> Trait for (i32, I) {
+LL + impl<, I: Iterator<Item = i32>> Trait for (i32, I) {
+   |
 
 error: aborting due to previous error
 
diff --git a/tests/ui/typeck/issue-13853-5.stderr b/tests/ui/typeck/issue-13853-5.stderr
index 3d8f824ec94cb..ecfe102a630f2 100644
--- a/tests/ui/typeck/issue-13853-5.stderr
+++ b/tests/ui/typeck/issue-13853-5.stderr
@@ -3,6 +3,12 @@ error[E0207]: the type parameter `T` is not constrained by the impl trait, self
    |
 LL | impl<'a, T: Deserializable> Deserializable for &'a str {
    |          ^ unconstrained type parameter
+   |
+help: Either remove the type parameter 'T' or make use of it, for example ` for S<T>`.
+   |
+LL - impl<'a, T: Deserializable> Deserializable for &'a str {
+LL + impl<'a, : Deserializable> Deserializable for &'a str {
+   |
 
 error: aborting due to previous error