introduce tests

tests/ui/dropck/const_drop_is_valid.rs

@@ -0,0 +1,11 @@
+#![feature(effects)]
+//~^ WARN: the feature `effects` is incomplete
+
+struct A();
+
+impl const Drop for A {}
+//~^ ERROR: const trait impls are experimental
+//~| const `impl` for trait `Drop` which is not marked with `#[const_trait]`
+//~| not all trait items implemented, missing: `drop`
+
+fn main() {}

tests/ui/dropck/const_drop_is_valid.stderr

@@ -0,0 +1,45 @@
+error[E0658]: const trait impls are experimental
+  --> $DIR/const_drop_is_valid.rs:6:6
+   |
+LL | impl const Drop for A {}
+   |      ^^^^^
+   |
+   = note: see issue #67792 <https://github.com/rust-lang/rust/issues/67792> for more information
+   = help: add `#![feature(const_trait_impl)]` to the crate attributes to enable
+   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
+
+warning: the feature `effects` is incomplete and may not be safe to use and/or cause compiler crashes
+  --> $DIR/const_drop_is_valid.rs:1:12
+   |
+LL | #![feature(effects)]
+   |            ^^^^^^^
+   |
+   = note: see issue #102090 <https://github.com/rust-lang/rust/issues/102090> for more information
+   = note: `#[warn(incomplete_features)]` on by default
+
+error: using `#![feature(effects)]` without enabling next trait solver globally
+   |
+   = note: the next trait solver must be enabled globally for the effects feature to work correctly
+   = help: use `-Znext-solver` to enable
+
+error: const `impl` for trait `Drop` which is not marked with `#[const_trait]`
+  --> $DIR/const_drop_is_valid.rs:6:12
+   |
+LL | impl const Drop for A {}
+   |            ^^^^
+   |
+   = note: marking a trait with `#[const_trait]` ensures all default method bodies are `const`
+   = note: adding a non-const method body in the future would be a breaking change
+
+error[E0046]: not all trait items implemented, missing: `drop`
+  --> $DIR/const_drop_is_valid.rs:6:1
+   |
+LL | impl const Drop for A {}
+   | ^^^^^^^^^^^^^^^^^^^^^ missing `drop` in implementation
+   |
+   = help: implement the missing item: `fn drop(&mut self) { todo!() }`
+
+error: aborting due to 4 previous errors; 1 warning emitted
+
+Some errors have detailed explanations: E0046, E0658.
+For more information about an error, try `rustc --explain E0046`.

tests/ui/dropck/constrained_by_assoc_type_equality.rs

@@ -0,0 +1,12 @@
+struct Foo<T: Trait>(T);
+
+trait Trait {
+    type Assoc;
+}
+
+impl<T: Trait<Assoc = U>, U: ?Sized> Drop for Foo<T> {
+    //~^ ERROR: `Drop` impl requires `<T as Trait>::Assoc == U`
+    fn drop(&mut self) {}
+}
+
+fn main() {}

tests/ui/dropck/constrained_by_assoc_type_equality.stderr

@@ -0,0 +1,15 @@
+error[E0367]: `Drop` impl requires `<T as Trait>::Assoc == U` but the struct it is implemented for does not
+  --> $DIR/constrained_by_assoc_type_equality.rs:7:15
+   |
+LL | impl<T: Trait<Assoc = U>, U: ?Sized> Drop for Foo<T> {
+   |               ^^^^^^^^^
+   |
+note: the implementor must specify the same requirement
+  --> $DIR/constrained_by_assoc_type_equality.rs:1:1
+   |
+LL | struct Foo<T: Trait>(T);
+   | ^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0367`.

tests/ui/dropck/unconstrained_const_param_on_drop.rs

@@ -0,0 +1,8 @@
+//@ known-bug: unknown
+//@ failure-status: 101
+
+struct Foo {}
+
+impl<const UNUSED: usize> Drop for Foo {}
+
+fn main() {}