rust-lang · rust-bors · Jul 27, 2026 · Jul 27, 2026
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -949,12 +949,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
                     }
                 } else if let Some(impl_did) = impl_did.as_local()
                     && let item = self.tcx.hir_expect_item(impl_did)
-                    && let hir::ItemKind::Impl(item) = item.kind
-                    && let Some(of_trait) = item.of_trait
+                    && let hir::ItemKind::Impl(impl_) = item.kind
+                    && impl_.of_trait.is_some()
                 {
                     // trait is const, impl is local and not const
                     diag.span_suggestion_verbose(
-                        of_trait.trait_ref.path.span.shrink_to_lo(),
+                        item.span.shrink_to_lo(),
                         format!("make the `impl` of trait `{trait_name}` `const`"),
                         "const ".to_string(),
                         Applicability::MaybeIncorrect,

diff --git a/tests/ui/comptime/comptime_impl.stderr b/tests/ui/comptime/comptime_impl.stderr
@@ -14,8 +14,8 @@ LL |     Bar.foo();
    |
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for Bar {
-   |      +++++
+LL | const impl Foo for Bar {
+   | +++++
 
 error[E0277]: the trait bound `Bar: const Foo` is not satisfied
   --> $DIR/comptime_impl.rs:31:9
@@ -25,8 +25,8 @@ LL |     Bar.bar();
    |
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for Bar {
-   |      +++++
+LL | const impl Foo for Bar {
+   | +++++
 
 error: aborting due to 3 previous errors
 

diff --git a/tests/ui/traits/const-traits/assoc-type.current.stderr b/tests/ui/traits/const-traits/assoc-type.current.stderr
@@ -11,8 +11,8 @@ LL |     type Bar: [const] Add;
    |               ^^^^^^^^^^^ required by this bound in `Foo::Bar`
 help: make the `impl` of trait `Add` `const`
    |
-LL | impl const Add for NonConstAdd {
-   |      +++++
+LL | const impl Add for NonConstAdd {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/assoc-type.next.stderr b/tests/ui/traits/const-traits/assoc-type.next.stderr
@@ -11,8 +11,8 @@ LL |     type Bar: [const] Add;
    |               ^^^^^^^^^^^ required by this bound in `Foo::Bar`
 help: make the `impl` of trait `Add` `const`
    |
-LL | impl const Add for NonConstAdd {
-   |      +++++
+LL | const impl Add for NonConstAdd {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/call-const-closure.next.stderr b/tests/ui/traits/const-traits/call-const-closure.next.stderr
@@ -6,8 +6,8 @@ LL |     (const || ().foo())();
    |
 help: make the `impl` of trait `Bar` `const`
    |
-LL | impl const Bar for () {
-   |      +++++
+LL | const impl Bar for () {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/call-const-closure.old.stderr b/tests/ui/traits/const-traits/call-const-closure.old.stderr
@@ -6,8 +6,8 @@ LL |     (const || ().foo())();
    |
 help: make the `impl` of trait `Bar` `const`
    |
-LL | impl const Bar for () {
-   |      +++++
+LL | const impl Bar for () {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/call-const-trait-method-fail.rs b/tests/ui/traits/const-traits/call-const-trait-method-fail.rs
@@ -5,6 +5,11 @@ pub const trait Plus {
     fn plus(self, rhs: Self) -> Self;
 }
 
+
+pub const unsafe trait Minus {
+    fn minus(self, rhs: Self) -> Self;
+}
+
 const impl Plus for i32 {
     fn plus(self, rhs: Self) -> Self {
         self + rhs
@@ -17,6 +22,20 @@ impl Plus for u32 {
     }
 }
 
+
+const unsafe impl Minus for i32 {
+    fn minus(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+unsafe impl Minus for u32 {
+    fn minus(self, rhs: Self) -> Self {
+        self - rhs
+    }
+}
+
+
 pub const fn add_i32(a: i32, b: i32) -> i32 {
     a.plus(b) // ok
 }
@@ -26,4 +45,15 @@ pub const fn add_u32(a: u32, b: u32) -> u32 {
     //~^ ERROR the trait bound `u32: [const] Plus`
 }
 
+
+pub const unsafe fn sub_i32(a: i32, b: i32) -> i32 {
+    a.minus(b) // ok
+}
+
+pub const unsafe fn sub_u32(a: u32, b: u32) -> u32 {
+    a.minus(b)
+    //~^ ERROR the trait bound `u32: [const] Minus`
+}
+
+
 fn main() {}
diff --git a/tests/ui/traits/const-traits/call-const-trait-method-fail.stderr b/tests/ui/traits/const-traits/call-const-trait-method-fail.stderr
@@ -1,14 +1,25 @@
 error[E0277]: the trait bound `u32: [const] Plus` is not satisfied
-  --> $DIR/call-const-trait-method-fail.rs:25:5
+  --> $DIR/call-const-trait-method-fail.rs:44:5
    |
 LL |     a.plus(b)
    |     ^
    |
 help: make the `impl` of trait `Plus` `const`
    |
-LL | impl const Plus for u32 {
-   |      +++++
+LL | const impl Plus for u32 {
+   | +++++
 
-error: aborting due to 1 previous error
+error[E0277]: the trait bound `u32: [const] Minus` is not satisfied
+  --> $DIR/call-const-trait-method-fail.rs:54:5
+   |
+LL |     a.minus(b)
+   |     ^
+   |
+help: make the `impl` of trait `Minus` `const`
+   |
+LL | const unsafe impl Minus for u32 {
+   | +++++
+
+error: aborting due to 2 previous errors
 
 For more information about this error, try `rustc --explain E0277`.
diff --git a/tests/ui/traits/const-traits/call-generic-method-nonconst.stderr b/tests/ui/traits/const-traits/call-generic-method-nonconst.stderr
@@ -13,8 +13,8 @@ LL | const fn equals_self<T: [const] Foo>(t: &T) -> bool {
    |                         ^^^^^^^^^^^ required by this bound in `equals_self`
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for S {
-   |      +++++
+LL | const impl Foo for S {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/const-closure-trait-method-fail.stderr b/tests/ui/traits/const-traits/const-closure-trait-method-fail.stderr
@@ -6,8 +6,8 @@ LL | const _: () = assert!(need_const_closure(Tr::a) == 42);
    |
 help: make the `impl` of trait `Tr` `const`
    |
-LL | impl const Tr for () {
-   |      +++++
+LL | const impl Tr for () {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/const-default-method-bodies.stderr b/tests/ui/traits/const-traits/const-default-method-bodies.stderr
@@ -6,8 +6,8 @@ LL |     NonConstImpl.a();
    |
 help: make the `impl` of trait `ConstDefaultFn` `const`
    |
-LL | impl const ConstDefaultFn for NonConstImpl {
-   |      +++++
+LL | const impl ConstDefaultFn for NonConstImpl {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/const-drop-fail-2.precise.stderr b/tests/ui/traits/const-traits/const-drop-fail-2.precise.stderr
@@ -18,8 +18,8 @@ LL | const fn check<T: [const] Destruct>(_: T) {}
    |                   ^^^^^^^^^^^^^^^^ required by this bound in `check`
 help: make the `impl` of trait `A` `const`
    |
-LL | impl const A for NonTrivialDrop {}
-   |      +++++
+LL | const impl A for NonTrivialDrop {}
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/const-drop-fail-2.stock.stderr b/tests/ui/traits/const-traits/const-drop-fail-2.stock.stderr
@@ -18,8 +18,8 @@ LL | const fn check<T: [const] Destruct>(_: T) {}
    |                   ^^^^^^^^^^^^^^^^ required by this bound in `check`
 help: make the `impl` of trait `A` `const`
    |
-LL | impl const A for NonTrivialDrop {}
-   |      +++++
+LL | const impl A for NonTrivialDrop {}
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/const-opaque.no.stderr b/tests/ui/traits/const-traits/const-opaque.no.stderr
@@ -13,8 +13,8 @@ LL | const fn bar<T: [const] Foo>(t: T) -> impl [const] Foo {
    |                 ^^^^^^^^^^^ required by this bound in `bar`
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for () {
-   |      +++++
+LL | const impl Foo for () {
+   | +++++
 
 error[E0277]: the trait bound `(): const Foo` is not satisfied
   --> $DIR/const-opaque.rs:32:12
@@ -24,8 +24,8 @@ LL |     opaque.method();
    |
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for () {
-   |      +++++
+LL | const impl Foo for () {
+   | +++++
 
 error: aborting due to 2 previous errors
 

diff --git a/tests/ui/traits/const-traits/default-method-body-is-const-body-checking.stderr b/tests/ui/traits/const-traits/default-method-body-is-const-body-checking.stderr
@@ -11,8 +11,8 @@ LL | const fn foo<T>() where T: [const] Tr {}
    |                            ^^^^^^^^^^ required by this bound in `foo`
 help: make the `impl` of trait `Tr` `const`
    |
-LL | impl const Tr for () {}
-   |      +++++
+LL | const impl Tr for () {}
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/default-method-body-is-const-same-trait-ck.stderr b/tests/ui/traits/const-traits/default-method-body-is-const-same-trait-ck.stderr
@@ -6,8 +6,8 @@ LL |         ().a()
    |
 help: make the `impl` of trait `Tr` `const`
    |
-LL | impl const Tr for () {}
-   |      +++++
+LL | const impl Tr for () {}
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/item-bound-entailment-fails.stderr b/tests/ui/traits/const-traits/item-bound-entailment-fails.stderr
@@ -11,8 +11,8 @@ LL |     type Assoc<T>: [const] Bar
    |                    ^^^^^^^^^^^ required by this bound in `Foo::Assoc`
 help: make the `impl` of trait `Bar` `const`
    |
-LL | impl<T> const Bar for N<T> where T: Bar {}
-   |         +++++
+LL | const impl<T> Bar for N<T> where T: Bar {}
+   | +++++
 
 error[E0277]: the trait bound `T: [const] Bar` is not satisfied
   --> $DIR/item-bound-entailment-fails.rs:24:21

diff --git a/tests/ui/traits/const-traits/minicore-deref-fail.stderr b/tests/ui/traits/const-traits/minicore-deref-fail.stderr
@@ -6,8 +6,8 @@ LL |     *Ty;
    |
 help: make the `impl` of trait `Deref` `const`
    |
-LL | impl const Deref for Ty {
-   |      +++++
+LL | const impl Deref for Ty {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/minicore-fn-fail.stderr b/tests/ui/traits/const-traits/minicore-fn-fail.stderr
@@ -13,8 +13,8 @@ LL | const fn call_indirect<T: [const] Fn()>(t: &T) { t() }
    |                           ^^^^^^^^^^^^ required by this bound in `call_indirect`
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for () {}
-   |      +++++
+LL | const impl Foo for () {}
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/no-explicit-const-params.stderr b/tests/ui/traits/const-traits/no-explicit-const-params.stderr
@@ -62,8 +62,8 @@ LL |     <() as Bar<false>>::bar();
    |
 help: make the `impl` of trait `Bar` `const`
    |
-LL | impl const Bar for () {
-   |      +++++
+LL | const impl Bar for () {
+   | +++++
 
 error: aborting due to 5 previous errors
 

diff --git a/tests/ui/traits/const-traits/specialization/specializing-constness-2.stderr b/tests/ui/traits/const-traits/specialization/specializing-constness-2.stderr
@@ -6,8 +6,8 @@ LL |     <T as A>::a();
    |
 help: make the `impl` of trait `A` `const`
    |
-LL | impl<T: Default> const A for T {
-   |                  +++++
+LL | const impl<T: Default> A for T {
+   | +++++
 
 error: aborting due to 1 previous error
 

diff --git a/tests/ui/traits/const-traits/super-traits-fail.stderr b/tests/ui/traits/const-traits/super-traits-fail.stderr
@@ -6,8 +6,8 @@ LL | const impl Bar for S {}
    |
 help: make the `impl` of trait `Foo` `const`
    |
-LL | impl const Foo for S {
-   |      +++++
+LL | const impl Foo for S {
+   | +++++
 
 error: aborting due to 1 previous error