1 files changed, 37 insertions, 0 deletions

diff --git a/tests/ui/issues/issue-42312.stderr b/tests/ui/issues/issue-42312.stderr
new file mode 100644
index 000000000..3ca6a2957
--- /dev/null
+++ b/tests/ui/issues/issue-42312.stderr
@@ -0,0 +1,37 @@
+error[E0277]: the size for values of type `<Self as Deref>::Target` cannot be known at compilation time
+  --> $DIR/issue-42312.rs:4:12
+   |
+LL |     fn baz(_: Self::Target) where Self: Deref {}
+   |            ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `<Self as Deref>::Target`
+   = help: unsized fn params are gated as an unstable feature
+help: consider further restricting the associated type
+   |
+LL |     fn baz(_: Self::Target) where Self: Deref, <Self as Deref>::Target: Sized {}
+   |                                              ++++++++++++++++++++++++++++++++
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL |     fn baz(_: &Self::Target) where Self: Deref {}
+   |               +
+
+error[E0277]: the size for values of type `(dyn ToString + 'static)` cannot be known at compilation time
+  --> $DIR/issue-42312.rs:8:10
+   |
+LL | pub fn f(_: dyn ToString) {}
+   |          ^ doesn't have a size known at compile-time
+   |
+   = help: the trait `Sized` is not implemented for `(dyn ToString + 'static)`
+   = help: unsized fn params are gated as an unstable feature
+help: you can use `impl Trait` as the argument type
+   |
+LL | pub fn f(_: impl ToString) {}
+   |             ~~~~
+help: function arguments must have a statically known size, borrowed types always have a known size
+   |
+LL | pub fn f(_: &dyn ToString) {}
+   |             +
+
+error: aborting due to 2 previous errors
+
+For more information about this error, try `rustc --explain E0277`.