diff --git a/src/test/ui/closures/issue-84044-drop-non-mut.rs b/src/test/ui/closures/issue-84044-drop-non-mut.rs
new file mode 100644
index 00000000000..aed7750f1b9
--- /dev/null
+++ b/src/test/ui/closures/issue-84044-drop-non-mut.rs
@@ -0,0 +1,6 @@
+// #84044: This used to ICE.
+
+fn main() {
+    let f = || {};
+    drop(&mut f); //~ ERROR cannot borrow `f` as mutable, as it is not declared as mutable
+}
diff --git a/src/test/ui/closures/issue-84044-drop-non-mut.stderr b/src/test/ui/closures/issue-84044-drop-non-mut.stderr
new file mode 100644
index 00000000000..c0bfad263f1
--- /dev/null
+++ b/src/test/ui/closures/issue-84044-drop-non-mut.stderr
@@ -0,0 +1,11 @@
+error[E0596]: cannot borrow `f` as mutable, as it is not declared as mutable
+  --> $DIR/issue-84044-drop-non-mut.rs:5:10
+   |
+LL |     let f = || {};
+   |         - help: consider changing this to be mutable: `mut f`
+LL |     drop(&mut f);
+   |          ^^^^^^ cannot borrow as mutable
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0596`.
diff --git a/src/test/ui/save-analysis/issue-89066.rs b/src/test/ui/save-analysis/issue-89066.rs
new file mode 100644
index 00000000000..2873f5237d4
--- /dev/null
+++ b/src/test/ui/save-analysis/issue-89066.rs
@@ -0,0 +1,28 @@
+// compile-flags: -Zsave-analysis
+
+// Check that this does not ICE.
+// Stolen from src/test/ui/const-generics/generic_arg_infer/infer-arg-test.rs
+
+#![feature(generic_arg_infer)]
+
+struct All<'a, T, const N: usize> {
+  v: &'a T,
+}
+
+struct BadInfer<_>;
+//~^ ERROR expected identifier
+//~| ERROR parameter `_` is never used
+
+fn all_fn<'a, T, const N: usize>() {}
+
+fn bad_infer_fn<_>() {}
+//~^ ERROR expected identifier
+
+
+fn main() {
+  let a: All<_, _, _>;
+  //~^ ERROR this struct takes 2 generic arguments but 3 generic arguments were supplied
+  all_fn();
+  let v: [u8; _];
+  let v: [u8; 10] = [0; _];
+}
diff --git a/src/test/ui/save-analysis/issue-89066.stderr b/src/test/ui/save-analysis/issue-89066.stderr
new file mode 100644
index 00000000000..a3ff1c02b2a
--- /dev/null
+++ b/src/test/ui/save-analysis/issue-89066.stderr
@@ -0,0 +1,39 @@
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/issue-89066.rs:12:17
+   |
+LL | struct BadInfer<_>;
+   |                 ^ expected identifier, found reserved identifier
+
+error: expected identifier, found reserved identifier `_`
+  --> $DIR/issue-89066.rs:18:17
+   |
+LL | fn bad_infer_fn<_>() {}
+   |                 ^ expected identifier, found reserved identifier
+
+error[E0392]: parameter `_` is never used
+  --> $DIR/issue-89066.rs:12:17
+   |
+LL | struct BadInfer<_>;
+   |                 ^ unused parameter
+   |
+   = help: consider removing `_`, referring to it in a field, or using a marker such as `PhantomData`
+   = help: if you intended `_` to be a const parameter, use `const _: usize` instead
+
+error[E0107]: this struct takes 2 generic arguments but 3 generic arguments were supplied
+  --> $DIR/issue-89066.rs:23:10
+   |
+LL |   let a: All<_, _, _>;
+   |          ^^^       - help: remove this generic argument
+   |          |
+   |          expected 2 generic arguments
+   |
+note: struct defined here, with 2 generic parameters: `T`, `N`
+  --> $DIR/issue-89066.rs:8:8
+   |
+LL | struct All<'a, T, const N: usize> {
+   |        ^^^     -        -
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0107, E0392.
+For more information about an error, try `rustc --explain E0107`.
diff --git a/src/test/ui/traits/issue-91594.rs b/src/test/ui/traits/issue-91594.rs
new file mode 100644
index 00000000000..930f7f0c6ad
--- /dev/null
+++ b/src/test/ui/traits/issue-91594.rs
@@ -0,0 +1,17 @@
+// #91594: This used to ICE.
+
+trait Component<M> {
+    type Interface;
+}
+trait HasComponent<I> {}
+
+struct Foo;
+
+impl HasComponent<<Foo as Component<Foo>>::Interface> for Foo {}
+//~^ ERROR the trait bound `Foo: HasComponent<()>` is not satisfied
+
+impl<M: HasComponent<()>> Component<M> for Foo {
+    type Interface = u8;
+}
+
+fn main() {}
diff --git a/src/test/ui/traits/issue-91594.stderr b/src/test/ui/traits/issue-91594.stderr
new file mode 100644
index 00000000000..10298a0c703
--- /dev/null
+++ b/src/test/ui/traits/issue-91594.stderr
@@ -0,0 +1,17 @@
+error[E0277]: the trait bound `Foo: HasComponent<()>` is not satisfied
+  --> $DIR/issue-91594.rs:10:6
+   |
+LL | impl HasComponent<<Foo as Component<Foo>>::Interface> for Foo {}
+   |      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `HasComponent<()>` is not implemented for `Foo`
+   |
+   = help: the following implementations were found:
+             <Foo as HasComponent<<Foo as Component<Foo>>::Interface>>
+note: required because of the requirements on the impl of `Component<Foo>` for `Foo`
+  --> $DIR/issue-91594.rs:13:27
+   |
+LL | impl<M: HasComponent<()>> Component<M> for Foo {
+   |                           ^^^^^^^^^^^^     ^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0277`.