add more tests for pathological implementations

crates/iddqd/README.md

@@ -255,9 +255,13 @@ This crate is validated through a combination of:
 
 * Unit tests
 * Property-based tests using a naive map as an oracle
-* Chaos tests for several kinds of buggy `Eq` and `Ord` implementations
-* Explicit tests for panic safety in some scenarios
-* Miri tests for unsafe code
+* Unit and property-based tests for several kinds of pathological `Eq`,
+  `Hash` and `Ord` implementations
+* Property-based tests for panic safety
+* Miri tests for unsafe code, checked against both Stacked and Tree Borrows
+
+Pathological user implementations written in safe Rust might corrupt
+internal map state and result in panics, but should never cause UB.
 
 If you see a gap in testing, new tests are welcome. Thank you!
 

crates/iddqd/src/lib.rs

@@ -283,9 +283,13 @@
 //!
 //! * Unit tests
 //! * Property-based tests using a naive map as an oracle
-//! * Chaos tests for several kinds of buggy `Eq` and `Ord` implementations
-//! * Explicit tests for panic safety in some scenarios
-//! * Miri tests for unsafe code
+//! * Unit and property-based tests for several kinds of pathological `Eq`,
+//!   `Hash` and `Ord` implementations
+//! * Property-based tests for panic safety
+//! * Miri tests for unsafe code, checked against both Stacked and Tree Borrows
+//!
+//! Pathological user implementations written in safe Rust might corrupt
+//! internal map state and result in panics, but should never cause UB.
 //!
 //! If you see a gap in testing, new tests are welcome. Thank you!
 //!

crates/iddqd/src/support/btree_table.rs

@@ -374,9 +374,8 @@ where
     move |a: &Index, b: &Index| {
         let (a, b) = (a.value(), b.value());
         if a == b {
-            // This is potentially load-bearing! It means that even if the Eq
-            // implementation on map items is wrong, we treat items at the same
-            // index as equal.
+            // This is load-bearing! It means that even if the Eq implementation
+            // on map items is wrong, we treat items at the same index as equal.
             //
             // Unsafe code relies on this to ensure that we don't return
             // multiple mutable references to the same index.

crates/iddqd/tests/integration/main.rs

@@ -4,6 +4,8 @@ mod id_hash_map;
 mod id_ord_map;
 #[cfg(any(feature = "std", feature = "default-hasher"))]
 mod panic_safety;
+#[cfg(all(feature = "std", feature = "default-hasher"))]
+mod pathological;
 #[cfg(feature = "schemars08")]
 mod schemars_tests;
 #[cfg(all(

crates/iddqd/tests/integration/panic_safety.rs

@@ -72,11 +72,11 @@ fn take_op_count() -> u32 {
     OP_COUNT.with(|c| c.replace(0))
 }
 
-fn arm_panic_after(n: u32) {
+pub(crate) fn arm_panic_after(n: u32) {
     PANIC_COUNTDOWN.with(|c| c.set(Some(n)));
 }
 
-fn disarm_panic() {
+pub(crate) fn disarm_panic() {
     PANIC_COUNTDOWN.with(|c| c.set(None));
 }