diff --git a/compiler/rustc_hir_analysis/locales/en-US.ftl b/compiler/rustc_hir_analysis/locales/en-US.ftl
index 1d313945b52..dfd083442ae 100644
--- a/compiler/rustc_hir_analysis/locales/en-US.ftl
+++ b/compiler/rustc_hir_analysis/locales/en-US.ftl
@@ -89,14 +89,14 @@ hir_analysis_missing_type_params =
     .note = because of the default `Self` reference, type parameters must be specified on object types
 
 hir_analysis_copy_impl_on_type_with_dtor =
-    the trait `Copy` may not be implemented for this type; the type has a destructor
+    the trait `Copy` cannot be implemented for this type; the type has a destructor
     .label = `Copy` not allowed on types with destructors
 
 hir_analysis_multiple_relaxed_default_bounds =
     type parameter has more than one relaxed default bound, only one is supported
 
 hir_analysis_copy_impl_on_non_adt =
-    the trait `Copy` may not be implemented for this type
+    the trait `Copy` cannot be implemented for this type
     .label = type is not a structure or enumeration
 
 hir_analysis_const_impl_for_non_const_trait =
diff --git a/compiler/rustc_hir_analysis/src/coherence/builtin.rs b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
index ffb68abf978..852c5768399 100644
--- a/compiler/rustc_hir_analysis/src/coherence/builtin.rs
+++ b/compiler/rustc_hir_analysis/src/coherence/builtin.rs
@@ -86,7 +86,7 @@ fn visit_implementation_of_copy(tcx: TyCtxt<'_>, impl_did: LocalDefId) {
                 tcx.sess,
                 span,
                 E0204,
-                "the trait `Copy` may not be implemented for this type"
+                "the trait `Copy` cannot be implemented for this type"
             );
 
             // We'll try to suggest constraining type parameters to fulfill the requirements of
diff --git a/compiler/rustc_hir_typeck/locales/en-US.ftl b/compiler/rustc_hir_typeck/locales/en-US.ftl
index adfcbc36a4d..2c537bf4064 100644
--- a/compiler/rustc_hir_typeck/locales/en-US.ftl
+++ b/compiler/rustc_hir_typeck/locales/en-US.ftl
@@ -4,14 +4,14 @@ hir_typeck_field_multiply_specified_in_initializer =
     .previous_use_label = first use of `{$ident}`
 
 hir_typeck_copy_impl_on_type_with_dtor =
-    the trait `Copy` may not be implemented for this type; the type has a destructor
+    the trait `Copy` cannot be implemented for this type; the type has a destructor
     .label = `Copy` not allowed on types with destructors
 
 hir_typeck_multiple_relaxed_default_bounds =
     type parameter has more than one relaxed default bound, only one is supported
 
 hir_typeck_copy_impl_on_non_adt =
-    the trait `Copy` may not be implemented for this type
+    the trait `Copy` cannot be implemented for this type
     .label = type is not a structure or enumeration
 
 hir_typeck_trait_object_declared_with_no_traits =
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs
index 520ae0edb09..427146941ad 100644
--- a/library/core/src/marker.rs
+++ b/library/core/src/marker.rs
@@ -324,7 +324,7 @@ pub trait StructuralEq {
 /// attempt to derive a `Copy` implementation, we'll get an error:
 ///
 /// ```text
-/// the trait `Copy` may not be implemented for this type; field `points` does not implement `Copy`
+/// the trait `Copy` cannot be implemented for this type; field `points` does not implement `Copy`
 /// ```
 ///
 /// Shared references (`&T`) are also `Copy`, so a type can be `Copy`, even when it holds
diff --git a/tests/ui/coherence/coherence-impls-copy.stderr b/tests/ui/coherence/coherence-impls-copy.stderr
index d40ffc48a29..21dbc606321 100644
--- a/tests/ui/coherence/coherence-impls-copy.stderr
+++ b/tests/ui/coherence/coherence-impls-copy.stderr
@@ -52,19 +52,19 @@ LL | impl Copy for [MyType] {}
    |
    = note: define and implement a trait or new type instead
 
-error[E0206]: the trait `Copy` may not be implemented for this type
+error[E0206]: the trait `Copy` cannot be implemented for this type
   --> $DIR/coherence-impls-copy.rs:21:15
    |
 LL | impl Copy for &'static mut MyType {}
    |               ^^^^^^^^^^^^^^^^^^^ type is not a structure or enumeration
 
-error[E0206]: the trait `Copy` may not be implemented for this type
+error[E0206]: the trait `Copy` cannot be implemented for this type
   --> $DIR/coherence-impls-copy.rs:25:15
    |
 LL | impl Copy for (MyType, MyType) {}
    |               ^^^^^^^^^^^^^^^^ type is not a structure or enumeration
 
-error[E0206]: the trait `Copy` may not be implemented for this type
+error[E0206]: the trait `Copy` cannot be implemented for this type
   --> $DIR/coherence-impls-copy.rs:30:15
    |
 LL | impl Copy for [MyType] {}
diff --git a/tests/ui/coherence/deep-bad-copy-reason.rs b/tests/ui/coherence/deep-bad-copy-reason.rs
index 80bbe387ac7..97fd3f719bf 100644
--- a/tests/ui/coherence/deep-bad-copy-reason.rs
+++ b/tests/ui/coherence/deep-bad-copy-reason.rs
@@ -31,7 +31,7 @@ impl<'tcx, T> Clone for List<'tcx, T> {
 }
 
 impl<'tcx, T> Copy for List<'tcx, T> {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn assert_is_copy<T: Copy>() {}
 
diff --git a/tests/ui/coherence/deep-bad-copy-reason.stderr b/tests/ui/coherence/deep-bad-copy-reason.stderr
index 168ee57263d..7b6dd4b380f 100644
--- a/tests/ui/coherence/deep-bad-copy-reason.stderr
+++ b/tests/ui/coherence/deep-bad-copy-reason.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/deep-bad-copy-reason.rs:33:24
    |
 LL | pub struct List<'tcx, T>(Interned<'tcx, ListS<T>>);
diff --git a/tests/ui/error-codes/E0184.stderr b/tests/ui/error-codes/E0184.stderr
index bb3017b6ec2..52f1f30a408 100644
--- a/tests/ui/error-codes/E0184.stderr
+++ b/tests/ui/error-codes/E0184.stderr
@@ -1,4 +1,4 @@
-error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
+error[E0184]: the trait `Copy` cannot be implemented for this type; the type has a destructor
   --> $DIR/E0184.rs:1:10
    |
 LL | #[derive(Copy)]
diff --git a/tests/ui/error-codes/E0206.rs b/tests/ui/error-codes/E0206.rs
index 0f3d427ce11..74738d81015 100644
--- a/tests/ui/error-codes/E0206.rs
+++ b/tests/ui/error-codes/E0206.rs
@@ -2,7 +2,7 @@
 struct Bar;
 
 impl Copy for &'static mut Bar { }
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {
 }
diff --git a/tests/ui/error-codes/E0206.stderr b/tests/ui/error-codes/E0206.stderr
index 57ae2647d33..60d8d7bfe98 100644
--- a/tests/ui/error-codes/E0206.stderr
+++ b/tests/ui/error-codes/E0206.stderr
@@ -1,4 +1,4 @@
-error[E0206]: the trait `Copy` may not be implemented for this type
+error[E0206]: the trait `Copy` cannot be implemented for this type
   --> $DIR/E0206.rs:4:15
    |
 LL | impl Copy for &'static mut Bar { }
diff --git a/tests/ui/exclusive-drop-and-copy.rs b/tests/ui/exclusive-drop-and-copy.rs
index 7a251671ee9..210ecaed756 100644
--- a/tests/ui/exclusive-drop-and-copy.rs
+++ b/tests/ui/exclusive-drop-and-copy.rs
@@ -1,13 +1,13 @@
 // issue #20126
 
-#[derive(Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented
+#[derive(Copy, Clone)] //~ ERROR the trait `Copy` cannot be implemented
 struct Foo;
 
 impl Drop for Foo {
     fn drop(&mut self) {}
 }
 
-#[derive(Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented
+#[derive(Copy, Clone)] //~ ERROR the trait `Copy` cannot be implemented
 struct Bar<T>(::std::marker::PhantomData<T>);
 
 impl<T> Drop for Bar<T> {
diff --git a/tests/ui/exclusive-drop-and-copy.stderr b/tests/ui/exclusive-drop-and-copy.stderr
index 8649c8abbfa..546079422a7 100644
--- a/tests/ui/exclusive-drop-and-copy.stderr
+++ b/tests/ui/exclusive-drop-and-copy.stderr
@@ -1,4 +1,4 @@
-error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
+error[E0184]: the trait `Copy` cannot be implemented for this type; the type has a destructor
   --> $DIR/exclusive-drop-and-copy.rs:3:10
    |
 LL | #[derive(Copy, Clone)]
@@ -6,7 +6,7 @@ LL | #[derive(Copy, Clone)]
    |
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0184]: the trait `Copy` may not be implemented for this type; the type has a destructor
+error[E0184]: the trait `Copy` cannot be implemented for this type; the type has a destructor
   --> $DIR/exclusive-drop-and-copy.rs:10:10
    |
 LL | #[derive(Copy, Clone)]
diff --git a/tests/ui/issues/issue-27340.rs b/tests/ui/issues/issue-27340.rs
index 61c77cc1ff3..aff37d95a3f 100644
--- a/tests/ui/issues/issue-27340.rs
+++ b/tests/ui/issues/issue-27340.rs
@@ -1,6 +1,6 @@
 struct Foo;
 #[derive(Copy, Clone)]
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 struct Bar(Foo);
 
 fn main() {}
diff --git a/tests/ui/issues/issue-27340.stderr b/tests/ui/issues/issue-27340.stderr
index 40889b86668..9caaffd9c9a 100644
--- a/tests/ui/issues/issue-27340.stderr
+++ b/tests/ui/issues/issue-27340.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/issue-27340.rs:2:10
    |
 LL | #[derive(Copy, Clone)]
diff --git a/tests/ui/opt-in-copy.rs b/tests/ui/opt-in-copy.rs
index 0b48418e464..d0257b5745d 100644
--- a/tests/ui/opt-in-copy.rs
+++ b/tests/ui/opt-in-copy.rs
@@ -5,7 +5,7 @@ struct IWantToCopyThis {
 }
 
 impl Copy for IWantToCopyThis {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 enum CantCopyThisEither {
     A,
@@ -17,6 +17,6 @@ enum IWantToCopyThisToo {
 }
 
 impl Copy for IWantToCopyThisToo {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/opt-in-copy.stderr b/tests/ui/opt-in-copy.stderr
index 4461567df0a..258ff16e6e4 100644
--- a/tests/ui/opt-in-copy.stderr
+++ b/tests/ui/opt-in-copy.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/opt-in-copy.rs:7:15
    |
 LL |     but_i_cant: CantCopyThis,
@@ -7,7 +7,7 @@ LL |     but_i_cant: CantCopyThis,
 LL | impl Copy for IWantToCopyThis {}
    |               ^^^^^^^^^^^^^^^
 
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/opt-in-copy.rs:19:15
    |
 LL |     ButICant(CantCopyThisEither),
diff --git a/tests/ui/range/range_traits-2.stderr b/tests/ui/range/range_traits-2.stderr
index 61facba535b..0829fc2ce9b 100644
--- a/tests/ui/range/range_traits-2.stderr
+++ b/tests/ui/range/range_traits-2.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/range_traits-2.rs:3:10
    |
 LL | #[derive(Copy, Clone)]
diff --git a/tests/ui/range/range_traits-3.stderr b/tests/ui/range/range_traits-3.stderr
index e54d17b329e..db19d1baec9 100644
--- a/tests/ui/range/range_traits-3.stderr
+++ b/tests/ui/range/range_traits-3.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/range_traits-3.rs:3:10
    |
 LL | #[derive(Copy, Clone)]
diff --git a/tests/ui/range/range_traits-6.stderr b/tests/ui/range/range_traits-6.stderr
index addc525f1fa..dfc74f87ca7 100644
--- a/tests/ui/range/range_traits-6.stderr
+++ b/tests/ui/range/range_traits-6.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/range_traits-6.rs:3:10
    |
 LL | #[derive(Copy, Clone)]
diff --git a/tests/ui/span/E0204.rs b/tests/ui/span/E0204.rs
index 174de8cdd63..8793a05c8a8 100644
--- a/tests/ui/span/E0204.rs
+++ b/tests/ui/span/E0204.rs
@@ -2,9 +2,9 @@ struct Foo {
     foo: Vec<u32>,
 }
 
-impl Copy for Foo { } //~ ERROR may not be implemented for this type
+impl Copy for Foo { } //~ ERROR cannot be implemented for this type
 
-#[derive(Copy)] //~ ERROR may not be implemented for this type
+#[derive(Copy)] //~ ERROR cannot be implemented for this type
 struct Foo2<'a> {
     ty: &'a mut bool,
 }
@@ -14,9 +14,9 @@ enum EFoo {
     Baz,
 }
 
-impl Copy for EFoo { } //~ ERROR may not be implemented for this type
+impl Copy for EFoo { } //~ ERROR cannot be implemented for this type
 
-#[derive(Copy)] //~ ERROR may not be implemented for this type
+#[derive(Copy)] //~ ERROR cannot be implemented for this type
 enum EFoo2<'a> {
     Bar(&'a mut bool),
     Baz,
diff --git a/tests/ui/span/E0204.stderr b/tests/ui/span/E0204.stderr
index 0b2166eed7e..3a0afb541ba 100644
--- a/tests/ui/span/E0204.stderr
+++ b/tests/ui/span/E0204.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/E0204.rs:5:15
    |
 LL |     foo: Vec<u32>,
@@ -7,7 +7,7 @@ LL |     foo: Vec<u32>,
 LL | impl Copy for Foo { }
    |               ^^^
 
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/E0204.rs:7:10
    |
 LL | #[derive(Copy)]
@@ -18,7 +18,7 @@ LL |     ty: &'a mut bool,
    |
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/E0204.rs:17:15
    |
 LL |     Bar { x: Vec<u32> },
@@ -27,7 +27,7 @@ LL |     Bar { x: Vec<u32> },
 LL | impl Copy for EFoo { }
    |               ^^^^
 
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/E0204.rs:19:10
    |
 LL | #[derive(Copy)]
diff --git a/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed b/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed
index 304360d48a2..47b35b412c0 100644
--- a/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed
+++ b/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.fixed
@@ -7,7 +7,7 @@ pub struct Vector2<T: Debug + Copy + Clone>{
     pub y: T
 }
 
-#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented for this type
+#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` cannot be implemented for this type
 pub struct AABB<K: Copy + Debug>{
     pub loc: Vector2<K>,
     pub size: Vector2<K>
diff --git a/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs b/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs
index 14e1fbb3311..771e9105c62 100644
--- a/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs
+++ b/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.rs
@@ -7,7 +7,7 @@ pub struct Vector2<T: Debug + Copy + Clone>{
     pub y: T
 }
 
-#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented for this type
+#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` cannot be implemented for this type
 pub struct AABB<K: Copy>{
     pub loc: Vector2<K>,
     pub size: Vector2<K>
diff --git a/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr b/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr
index faf730a5ce3..83bc65ea1c8 100644
--- a/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr
+++ b/tests/ui/suggestions/missing-bound-in-derive-copy-impl-3.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/missing-bound-in-derive-copy-impl-3.rs:10:17
    |
 LL | #[derive(Debug, Copy, Clone)]
diff --git a/tests/ui/suggestions/missing-bound-in-derive-copy-impl.rs b/tests/ui/suggestions/missing-bound-in-derive-copy-impl.rs
index 52163bddd4f..9c7b7ba099c 100644
--- a/tests/ui/suggestions/missing-bound-in-derive-copy-impl.rs
+++ b/tests/ui/suggestions/missing-bound-in-derive-copy-impl.rs
@@ -6,7 +6,7 @@ pub struct Vector2<T: Debug + Copy + Clone>{
     pub y: T
 }
 
-#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` may not be implemented for this type
+#[derive(Debug, Copy, Clone)] //~ ERROR the trait `Copy` cannot be implemented for this type
 pub struct AABB<K>{
     pub loc: Vector2<K>,
     pub size: Vector2<K>
diff --git a/tests/ui/suggestions/missing-bound-in-derive-copy-impl.stderr b/tests/ui/suggestions/missing-bound-in-derive-copy-impl.stderr
index 11bc5409917..65dc3113731 100644
--- a/tests/ui/suggestions/missing-bound-in-derive-copy-impl.stderr
+++ b/tests/ui/suggestions/missing-bound-in-derive-copy-impl.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/missing-bound-in-derive-copy-impl.rs:9:17
    |
 LL | #[derive(Debug, Copy, Clone)]
diff --git a/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.fixed b/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.fixed
index 691e7553a09..f32c61a99bb 100644
--- a/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.fixed
+++ b/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.fixed
@@ -14,6 +14,6 @@ impl<T: std::fmt::Display> Clone for OnlyCopyIfDisplay<T> {
 impl<T: std::fmt::Display> Copy for OnlyCopyIfDisplay<T> {}
 
 impl<S: std::fmt::Display> Copy for Wrapper<OnlyCopyIfDisplay<S>> {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.rs b/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.rs
index e3185e7eff8..d7725f4a374 100644
--- a/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.rs
+++ b/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.rs
@@ -14,6 +14,6 @@ impl<T: std::fmt::Display> Clone for OnlyCopyIfDisplay<T> {
 impl<T: std::fmt::Display> Copy for OnlyCopyIfDisplay<T> {}
 
 impl<S> Copy for Wrapper<OnlyCopyIfDisplay<S>> {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.stderr b/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.stderr
index 9e6f0d9ebbd..856d8db381b 100644
--- a/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.stderr
+++ b/tests/ui/suggestions/missing-bound-in-manual-copy-impl-2.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/missing-bound-in-manual-copy-impl-2.rs:16:18
    |
 LL | struct Wrapper<T>(T);
diff --git a/tests/ui/suggestions/missing-bound-in-manual-copy-impl.fixed b/tests/ui/suggestions/missing-bound-in-manual-copy-impl.fixed
index 32a7215c5bd..1139b315313 100644
--- a/tests/ui/suggestions/missing-bound-in-manual-copy-impl.fixed
+++ b/tests/ui/suggestions/missing-bound-in-manual-copy-impl.fixed
@@ -4,6 +4,6 @@
 struct Wrapper<T>(T);
 
 impl<S: Copy> Copy for Wrapper<S> {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/suggestions/missing-bound-in-manual-copy-impl.rs b/tests/ui/suggestions/missing-bound-in-manual-copy-impl.rs
index c688f4d41ee..19549248efc 100644
--- a/tests/ui/suggestions/missing-bound-in-manual-copy-impl.rs
+++ b/tests/ui/suggestions/missing-bound-in-manual-copy-impl.rs
@@ -4,6 +4,6 @@
 struct Wrapper<T>(T);
 
 impl<S> Copy for Wrapper<S> {}
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/suggestions/missing-bound-in-manual-copy-impl.stderr b/tests/ui/suggestions/missing-bound-in-manual-copy-impl.stderr
index fe2d133c8aa..ec3e4f23a64 100644
--- a/tests/ui/suggestions/missing-bound-in-manual-copy-impl.stderr
+++ b/tests/ui/suggestions/missing-bound-in-manual-copy-impl.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/missing-bound-in-manual-copy-impl.rs:6:18
    |
 LL | struct Wrapper<T>(T);
diff --git a/tests/ui/traits/copy-is-not-modulo-regions.not_static.stderr b/tests/ui/traits/copy-is-not-modulo-regions.not_static.stderr
index edd94d2010b..13042521184 100644
--- a/tests/ui/traits/copy-is-not-modulo-regions.not_static.stderr
+++ b/tests/ui/traits/copy-is-not-modulo-regions.not_static.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/copy-is-not-modulo-regions.rs:13:21
    |
 LL | struct Bar<'lt>(Foo<'lt>);
diff --git a/tests/ui/traits/copy-is-not-modulo-regions.rs b/tests/ui/traits/copy-is-not-modulo-regions.rs
index adb87023769..b899083747a 100644
--- a/tests/ui/traits/copy-is-not-modulo-regions.rs
+++ b/tests/ui/traits/copy-is-not-modulo-regions.rs
@@ -11,7 +11,7 @@ struct Bar<'lt>(Foo<'lt>);
 
 #[cfg(not_static)]
 impl<'any> Copy for Bar<'any> {}
-//[not_static]~^ the trait `Copy` may not be implemented for this type
+//[not_static]~^ the trait `Copy` cannot be implemented for this type
 
 #[cfg(yes_static)]
 impl<'any> Copy for Bar<'static> {}
diff --git a/tests/ui/traits/issue-50480.rs b/tests/ui/traits/issue-50480.rs
index 005939e0c46..683a85a32c1 100644
--- a/tests/ui/traits/issue-50480.rs
+++ b/tests/ui/traits/issue-50480.rs
@@ -1,5 +1,5 @@
 #[derive(Clone, Copy)]
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 //~^ ERROR cannot find type `NotDefined` in this scope
 //~| ERROR cannot find type `NotDefined` in this scope
@@ -7,7 +7,7 @@ struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 //~| ERROR cannot find type `N` in this scope
 
 #[derive(Clone, Copy)]
-//~^ ERROR the trait `Copy` may not be implemented for this type
+//~^ ERROR the trait `Copy` cannot be implemented for this type
 struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
 //~^ ERROR cannot find type `NotDefined` in this scope
 //~| ERROR cannot find type `N` in this scope
diff --git a/tests/ui/traits/issue-50480.stderr b/tests/ui/traits/issue-50480.stderr
index 5063fdca092..4f72db60a16 100644
--- a/tests/ui/traits/issue-50480.stderr
+++ b/tests/ui/traits/issue-50480.stderr
@@ -60,7 +60,7 @@ error[E0412]: cannot find type `NotDefined` in this scope
 LL | struct Bar<T>(T, N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |                     ^^^^^^^^^^ not found in this scope
 
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/issue-50480.rs:1:17
    |
 LL | #[derive(Clone, Copy)]
@@ -73,7 +73,7 @@ LL | struct Foo(N, NotDefined, <i32 as Iterator>::Item, Vec<i32>, String);
    |
    = note: this error originates in the derive macro `Copy` (in Nightly builds, run with -Z macro-backtrace for more info)
 
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/issue-50480.rs:9:17
    |
 LL | #[derive(Clone, Copy)]
diff --git a/tests/ui/union/union-copy.rs b/tests/ui/union/union-copy.rs
index 5c3f8d90898..7ad0a11c6ac 100644
--- a/tests/ui/union/union-copy.rs
+++ b/tests/ui/union/union-copy.rs
@@ -9,6 +9,6 @@ union W {
 }
 
 impl Copy for U {} // OK
-impl Copy for W {} //~ ERROR the trait `Copy` may not be implemented for this type
+impl Copy for W {} //~ ERROR the trait `Copy` cannot be implemented for this type
 
 fn main() {}
diff --git a/tests/ui/union/union-copy.stderr b/tests/ui/union/union-copy.stderr
index 53ee4dd2e5b..ff6fa48db90 100644
--- a/tests/ui/union/union-copy.stderr
+++ b/tests/ui/union/union-copy.stderr
@@ -1,4 +1,4 @@
-error[E0204]: the trait `Copy` may not be implemented for this type
+error[E0204]: the trait `Copy` cannot be implemented for this type
   --> $DIR/union-copy.rs:12:15
    |
 LL |     a: std::mem::ManuallyDrop<String>