On E0195 point at where clause lifetime bounds

Fix #104733

2 files changed, 57 insertions, 0 deletions

diff --git a/src/test/ui/trait-bounds/impl-missing-where-clause-lifetimes-from-trait.rs b/src/test/ui/trait-bounds/impl-missing-where-clause-lifetimes-from-trait.rs
new file mode 100644
index 00000000000..1994120ce14
--- /dev/null
+++ b/src/test/ui/trait-bounds/impl-missing-where-clause-lifetimes-from-trait.rs
@@ -0,0 +1,30 @@
+trait Trait<T> {
+    fn foo<'a, K>(self, _: T, _: K) where T: 'a, K: 'a;
+}
+
+impl Trait<()> for () {
+    fn foo<'a, K>(self, _: (), _: K) where { //~ ERROR E0195
+        todo!();
+    }
+}
+
+struct State;
+
+trait Foo<T> {
+    fn foo<'a>(&self, state: &'a State) -> &'a T
+    where
+        T: 'a;
+}
+
+impl<F, T> Foo<T> for F
+where
+    F: Fn(&State) -> &T,
+{
+    fn foo<'a>(&self, state: &'a State) -> &'a T { //~ ERROR E0195
+        self(state)
+    }
+}
+
+fn main() {
+    ().foo((), ());
+}
diff --git a/src/test/ui/trait-bounds/impl-missing-where-clause-lifetimes-from-trait.stderr b/src/test/ui/trait-bounds/impl-missing-where-clause-lifetimes-from-trait.stderr
new file mode 100644
index 00000000000..3a02369e2ee
--- /dev/null
+++ b/src/test/ui/trait-bounds/impl-missing-where-clause-lifetimes-from-trait.stderr
@@ -0,0 +1,27 @@
+error[E0195]: lifetime parameters or bounds on method `foo` do not match the trait declaration
+  --> $DIR/impl-missing-where-clause-lifetimes-from-trait.rs:6:11
+   |
+LL |     fn foo<'a, K>(self, _: T, _: K) where T: 'a, K: 'a;
+   |           -------                            --     -- this bound might be missing in the impl
+   |           |                                  |
+   |           |                                  this bound might be missing in the impl
+   |           lifetimes in impl do not match this method in trait
+...
+LL |     fn foo<'a, K>(self, _: (), _: K) where {
+   |           ^^^^^^^ lifetimes do not match method in trait
+
+error[E0195]: lifetime parameters or bounds on method `foo` do not match the trait declaration
+  --> $DIR/impl-missing-where-clause-lifetimes-from-trait.rs:23:11
+   |
+LL |     fn foo<'a>(&self, state: &'a State) -> &'a T
+   |           ---- lifetimes in impl do not match this method in trait
+LL |     where
+LL |         T: 'a;
+   |            -- this bound might be missing in the impl
+...
+LL |     fn foo<'a>(&self, state: &'a State) -> &'a T {
+   |           ^^^^ lifetimes do not match method in trait
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0195`.