Document that swisstable and b-tree containers are not exception-safe.

For performance reasons, these containers are optimized for the case in which allocations/deallocations/comparisons/hashers can't throw exceptions.

PiperOrigin-RevId: 645054627
Change-Id: I99be651b26f5bbb87da6ef246b92b20a375224d7

absl/container/btree_map.h

@@ -49,6 +49,8 @@
 //
 // Another API difference is that btree iterators can be subtracted, and this
 // is faster than using std::distance.
+//
+// B-tree maps are not exception-safe.
 
 #ifndef ABSL_CONTAINER_BTREE_MAP_H_
 #define ABSL_CONTAINER_BTREE_MAP_H_

absl/container/btree_set.h

@@ -48,6 +48,8 @@
 //
 // Another API difference is that btree iterators can be subtracted, and this
 // is faster than using std::distance.
+//
+// B-tree sets are not exception-safe.
 
 #ifndef ABSL_CONTAINER_BTREE_SET_H_
 #define ABSL_CONTAINER_BTREE_SET_H_

absl/container/flat_hash_map.h

@@ -26,6 +26,8 @@
 //
 // In most cases, your default choice for a hash map should be a map of type
 // `flat_hash_map`.
+//
+// `flat_hash_map` is not exception-safe.
 
 #ifndef ABSL_CONTAINER_FLAT_HASH_MAP_H_
 #define ABSL_CONTAINER_FLAT_HASH_MAP_H_

absl/container/flat_hash_set.h

@@ -26,6 +26,9 @@
 //
 // In most cases, your default choice for a hash set should be a set of type
 // `flat_hash_set`.
+//
+// `flat_hash_set` is not exception-safe.
+
 #ifndef ABSL_CONTAINER_FLAT_HASH_SET_H_
 #define ABSL_CONTAINER_FLAT_HASH_SET_H_
 

absl/container/node_hash_map.h

@@ -32,6 +32,8 @@
 // migration, because it guarantees pointer stability. Consider migrating to
 // `node_hash_map` and perhaps converting to a more efficient `flat_hash_map`
 // upon further review.
+//
+// `node_hash_map` is not exception-safe.
 
 #ifndef ABSL_CONTAINER_NODE_HASH_MAP_H_
 #define ABSL_CONTAINER_NODE_HASH_MAP_H_

absl/container/node_hash_set.h

@@ -31,6 +31,8 @@
 // `node_hash_set` should be an easy migration. Consider migrating to
 // `node_hash_set` and perhaps converting to a more efficient `flat_hash_set`
 // upon further review.
+//
+// `node_hash_set` is not exception-safe.
 
 #ifndef ABSL_CONTAINER_NODE_HASH_SET_H_
 #define ABSL_CONTAINER_NODE_HASH_SET_H_