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-rw-r--r--tests/ui/traits/cycle-cache-err-60010.rs74
1 files changed, 74 insertions, 0 deletions
diff --git a/tests/ui/traits/cycle-cache-err-60010.rs b/tests/ui/traits/cycle-cache-err-60010.rs
new file mode 100644
index 000000000..94e718317
--- /dev/null
+++ b/tests/ui/traits/cycle-cache-err-60010.rs
@@ -0,0 +1,74 @@
+// Test that we properly detect the cycle amongst the traits
+// here and report an error.
+
+use std::panic::RefUnwindSafe;
+
+trait Database {
+ type Storage;
+}
+trait HasQueryGroup {}
+trait Query<DB> {
+ type Data;
+}
+trait SourceDatabase {
+ fn parse(&self) {
+ loop {}
+ }
+}
+
+struct ParseQuery;
+struct RootDatabase {
+ _runtime: Runtime<RootDatabase>,
+}
+struct Runtime<DB: Database> {
+ _storage: Box<DB::Storage>,
+}
+struct SalsaStorage {
+ _parse: <ParseQuery as Query<RootDatabase>>::Data,
+ //~^ ERROR overflow
+}
+
+impl Database for RootDatabase {
+ // This would also be an error if we didn't abort compilation on the error
+ // above.
+ type Storage = SalsaStorage;
+}
+impl HasQueryGroup for RootDatabase {}
+impl<DB> Query<DB> for ParseQuery
+where
+ DB: SourceDatabase,
+ DB: Database,
+{
+ type Data = RootDatabase;
+}
+impl<T> SourceDatabase for T
+where
+ T: RefUnwindSafe,
+ T: HasQueryGroup,
+{
+}
+
+pub(crate) fn goto_implementation(db: &RootDatabase) -> u32 {
+ // This is not satisfied:
+ //
+ // - `RootDatabase: SourceDatabase`
+ // - requires `RootDatabase: RefUnwindSafe` + `RootDatabase: HasQueryGroup`
+ // - `RootDatabase: RefUnwindSafe`
+ // - requires `Runtime<RootDatabase>: RefUnwindSafe`
+ // - `Runtime<RootDatabase>: RefUnwindSafe`
+ // - requires `DB::Storage: RefUnwindSafe` (`SalsaStorage: RefUnwindSafe`)
+ // - `SalsaStorage: RefUnwindSafe`
+ // - requires `<ParseQuery as Query<RootDatabase>>::Data: RefUnwindSafe`,
+ // which means `ParseQuery: Query<RootDatabase>`
+ // - `ParseQuery: Query<RootDatabase>`
+ // - requires `RootDatabase: SourceDatabase`,
+ // - `RootDatabase: SourceDatabase` is already on the stack, so we have a
+ // cycle with non-coinductive participants
+ //
+ // we used to fail to report an error here because we got the
+ // caching wrong.
+ SourceDatabase::parse(db);
+ 22
+}
+
+fn main() {}