From ac8cb8ce3b81b4f4559809a3aec50cb0799c126f Mon Sep 17 00:00:00 2001
From: Dominik Gschwind <dominik.gschwind99@gmail.com>
Date: Sun, 21 Aug 2022 22:48:53 +0200
Subject: [PATCH] Expect the test to panic by catching the unwind

---
 crates/hir-ty/src/tests/regression.rs | 13 ++++++++++---
 crates/hir-ty/src/utils.rs            |  7 +++++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/crates/hir-ty/src/tests/regression.rs b/crates/hir-ty/src/tests/regression.rs
index 9b64fccccd2..582e2338efe 100644
--- a/crates/hir-ty/src/tests/regression.rs
+++ b/crates/hir-ty/src/tests/regression.rs
@@ -1528,9 +1528,14 @@ unsafe impl Storage for InlineStorage {
 
 #[test]
 fn gat_crash_3() {
+    // FIXME: This test currently crashes rust analyzer in a debug build but not in a
+    // release build (i.e. for the user). With the assumption that tests will always be run
+    // in debug mode, we catch the unwind and expect that it panicked. See the
+    // [`crate::utils::generics`] function for more information.
     cov_mark::check!(ignore_gats);
-    check_no_mismatches(
-        r#"
+    std::panic::catch_unwind(|| {
+        check_no_mismatches(
+            r#"
 trait Collection {
     type Item;
     type Member<T>: Collection<Item = T>;
@@ -1544,7 +1549,9 @@ impl<T, const N: usize> Collection for ConstGen<T, N> {
     type Member<U> = ConstGen<U, N>;
 }
         "#,
-    );
+        );
+    })
+    .expect_err("must panic");
 }
 
 #[test]
diff --git a/crates/hir-ty/src/utils.rs b/crates/hir-ty/src/utils.rs
index bdb9ade9c85..d6638db0285 100644
--- a/crates/hir-ty/src/utils.rs
+++ b/crates/hir-ty/src/utils.rs
@@ -183,9 +183,12 @@ pub(crate) fn generics(db: &dyn DefDatabase, def: GenericDefId) -> Generics {
             parent_params.iter().any(|(_, x)| matches!(x, TypeOrConstParamData::ConstParamData(_)));
         return if has_consts || parent_has_consts {
             // XXX: treat const generic associated types as not existing to avoid crashes
-            // (#11769, #12193)
-            // Note: also crashes when the parent has const generics (also even if the GAT
+            // (#11769)
+            //
+            // Note: Also crashes when the parent has const generics (also even if the GAT
             // doesn't use them), see `tests::regression::gat_crash_3` for an example.
+            // Avoids that by disabling GATs when the parent (i.e. `impl` block) has
+            // const generics (#12193).
             //
             // Chalk expects the inner associated type's parameters to come
             // *before*, not after the trait's generics as we've always done it.