From 3ca40f7c08718a44c6d08d2cbe060244340e7157 Mon Sep 17 00:00:00 2001
From: Florian Diebold <flodiebold@gmail.com>
Date: Sat, 30 Nov 2019 12:39:21 +0100
Subject: Add cycle recovery for generic predicates

---
 crates/ra_hir_ty/src/db.rs    | 1 +
 crates/ra_hir_ty/src/lower.rs | 9 +++++++++
 crates/ra_hir_ty/src/tests.rs | 8 --------
 3 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/crates/ra_hir_ty/src/db.rs b/crates/ra_hir_ty/src/db.rs
index 6ecc0b096..8e461e359 100644
--- a/crates/ra_hir_ty/src/db.rs
+++ b/crates/ra_hir_ty/src/db.rs
@@ -41,6 +41,7 @@ pub trait HirDatabase: DefDatabase {
     fn callable_item_signature(&self, def: CallableDef) -> FnSig;
 
     #[salsa::invoke(crate::lower::generic_predicates_for_param_query)]
+    #[salsa::cycle(crate::lower::generic_predicates_for_param_recover)]
     fn generic_predicates_for_param(
         &self,
         def: GenericDefId,
diff --git a/crates/ra_hir_ty/src/lower.rs b/crates/ra_hir_ty/src/lower.rs
index a646406f1..c6ee75c7a 100644
--- a/crates/ra_hir_ty/src/lower.rs
+++ b/crates/ra_hir_ty/src/lower.rs
@@ -532,6 +532,15 @@ pub(crate) fn generic_predicates_for_param_query(
         .collect()
 }
 
+pub(crate) fn generic_predicates_for_param_recover(
+    _db: &impl HirDatabase,
+    _cycle: &[String],
+    _def: &GenericDefId,
+    _param_idx: &u32,
+) -> Arc<[GenericPredicate]> {
+    Arc::new([])
+}
+
 impl TraitEnvironment {
     pub fn lower(db: &impl HirDatabase, resolver: &Resolver) -> Arc<TraitEnvironment> {
         let predicates = resolver
diff --git a/crates/ra_hir_ty/src/tests.rs b/crates/ra_hir_ty/src/tests.rs
index b72f0f279..552eb8f75 100644
--- a/crates/ra_hir_ty/src/tests.rs
+++ b/crates/ra_hir_ty/src/tests.rs
@@ -4718,10 +4718,6 @@ fn test() {
 }
 
 #[test]
-// FIXME this is currently a Salsa panic; it would be nicer if it just returned
-// in Unknown, and we should be able to do that once Salsa allows us to handle
-// the cycle. But at least it doesn't overflow for now.
-#[should_panic]
 fn unselected_projection_in_trait_env_cycle_1() {
     let t = type_at(
         r#"
@@ -4742,10 +4738,6 @@ fn test<T: Trait>() where T: Trait2<T::Item> {
 }
 
 #[test]
-// FIXME this is currently a Salsa panic; it would be nicer if it just returned
-// in Unknown, and we should be able to do that once Salsa allows us to handle
-// the cycle. But at least it doesn't overflow for now.
-#[should_panic]
 fn unselected_projection_in_trait_env_cycle_2() {
     let t = type_at(
         r#"
-- 
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