1 files changed, 106 insertions, 0 deletions
diff --git a/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/trait_impl_orphan.rs b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/trait_impl_orphan.rs
new file mode 100644
index 000000000..159d87d26
--- /dev/null
+++ b/src/tools/rust-analyzer/crates/ide-diagnostics/src/handlers/trait_impl_orphan.rs
@@ -0,0 +1,106 @@
+use hir::InFile;
+
+use crate::{Diagnostic, DiagnosticCode, DiagnosticsContext};
+
+// Diagnostic: trait-impl-orphan
+//
+// Only traits defined in the current crate can be implemented for arbitrary types
+pub(crate) fn trait_impl_orphan(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::TraitImplOrphan,
+) -> Diagnostic {
+    Diagnostic::new_with_syntax_node_ptr(
+        ctx,
+        DiagnosticCode::RustcHardError("E0117"),
+        format!("only traits defined in the current crate can be implemented for arbitrary types"),
+        InFile::new(d.file_id, d.impl_.clone().into()),
+    )
+    // Not yet checked for false positives
+    .experimental()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::check_diagnostics;
+
+    #[test]
+    fn simple() {
+        check_diagnostics(
+            r#"
+//- /foo.rs crate:foo
+pub trait Foo {}
+//- /bar.rs crate:bar
+pub struct Bar;
+//- /main.rs crate:main deps:foo,bar
+struct LocalType;
+trait LocalTrait {}
+  impl foo::Foo for bar::Bar {}
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: only traits defined in the current crate can be implemented for arbitrary types
+impl foo::Foo for LocalType {}
+impl LocalTrait for bar::Bar {}
+"#,
+        );
+    }
+
+    #[test]
+    fn generics() {
+        check_diagnostics(
+            r#"
+//- /foo.rs crate:foo
+pub trait Foo<T> {}
+//- /bar.rs crate:bar
+pub struct Bar<T>(T);
+//- /main.rs crate:main deps:foo,bar
+struct LocalType<T>;
+trait LocalTrait<T> {}
+  impl<T> foo::Foo<T> for bar::Bar<T> {}
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: only traits defined in the current crate can be implemented for arbitrary types
+
+  impl<T> foo::Foo<T> for bar::Bar<LocalType<T>> {}
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: only traits defined in the current crate can be implemented for arbitrary types
+
+  impl<T> foo::Foo<LocalType<T>> for bar::Bar<T> {}
+
+  impl<T> foo::Foo<bar::Bar<LocalType<T>>> for bar::Bar<LocalType<T>> {}
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: only traits defined in the current crate can be implemented for arbitrary types
+"#,
+        );
+    }
+
+    #[test]
+    fn fundamental() {
+        check_diagnostics(
+            r#"
+//- /foo.rs crate:foo
+pub trait Foo<T> {}
+//- /bar.rs crate:bar
+pub struct Bar<T>(T);
+#[lang = "owned_box"]
+#[fundamental]
+pub struct Box<T>(T);
+//- /main.rs crate:main deps:foo,bar
+struct LocalType;
+  impl<T> foo::Foo<T> for bar::Box<T> {}
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ error: only traits defined in the current crate can be implemented for arbitrary types
+  impl<T> foo::Foo<T> for &LocalType {}
+  impl<T> foo::Foo<T> for bar::Box<LocalType> {}
+"#,
+        );
+    }
+
+    #[test]
+    fn dyn_object() {
+        check_diagnostics(
+            r#"
+//- /foo.rs crate:foo
+pub trait Foo<T> {}
+//- /bar.rs crate:bar
+pub struct Bar;
+//- /main.rs crate:main deps:foo,bar
+trait LocalTrait {}
+impl<T> foo::Foo<T> for dyn LocalTrait {}
+impl<T> foo::Foo<dyn LocalTrait> for Bar {}
+"#,
+        );
+    }
+}