Follow up on requested changes from #5359 (#5368)

#5359 was merged and then there were some additional changes requested.
This pull request implements those changes.
- [fix a comment
typo](#5359 (comment))
- [avoid nested C API calls and fix memory
leak](#5359 (comment))
- [add a test with schema
evolution](#5359 (comment))

---
TYPE: BUG
DESC: Follow up on #5359

test/src/unit-cppapi-enumerations.cc

@@ -902,6 +902,34 @@ TEST_CASE_METHOD(
   REQUIRE(rc != TILEDB_OK);
 }
 
+TEST_CASE_METHOD(
+    CPPEnumerationFx,
+    "C API: ArraySchemaEvolution - Add Enumeration, retrieve with "
+    "ArraySchema::get_enumeration_from_name",
+    "[enumeration][array-schema-evolution][array-schema-get-enumeration-from-"
+    "name][rest]") {
+  create_array();
+
+  // Evolve once to add an enumeration.
+  ArraySchemaEvolution ase(ctx_);
+  std::vector<std::string> var_values{"one", "two", "three"};
+  auto var_enmr = Enumeration::create(ctx_, "ase_var_enmr", var_values);
+  ase.add_enumeration(var_enmr);
+  auto attr4 = Attribute::create<uint16_t>(ctx_, "attr4");
+  AttributeExperimental::set_enumeration_name(ctx_, attr4, "ase_var_enmr");
+  ase.add_attribute(attr4);
+  // Apply evolution to the array and reopen.
+  ase.array_evolve(uri_);
+
+  auto schema = Array::load_schema(ctx_, uri_);
+  auto actual_enumeration = ArraySchemaExperimental::get_enumeration_from_name(
+      ctx_, schema, "ase_var_enmr");
+
+  CHECK(test::is_equivalent_enumeration(
+      *var_enmr.ptr()->enumeration(),
+      *actual_enumeration.ptr()->enumeration()));
+}
+
 TEST_CASE_METHOD(
     CPPEnumerationFx,
     "CPP: Enumeration Query - Basic",

tiledb/api/c_api/array_schema/array_schema_api.cc

@@ -210,24 +210,30 @@ capi_return_t tiledb_array_schema_get_enumeration_from_attribute_name(
   ensure_array_schema_is_valid(array_schema);
   ensure_output_pointer_is_valid(enumeration);
 
-  tiledb_attribute_t* attribute;
-  capi_return_t getattr = tiledb_array_schema_get_attribute_from_name(
-      ctx, array_schema, attribute_name, &attribute);
-  if (tiledb_status(getattr) != TILEDB_OK) {
-    return getattr;
+  if (attribute_name == nullptr) {
+    throw CAPIException("'attribute_name' must not be null");
+  }
+  std::string attribute_name_string(attribute_name);
+  auto found_attr = array_schema->shared_attribute(attribute_name_string);
+  if (!found_attr) {
+    throw CAPIException(
+        std::string("Attribute name: ") +
+        (attribute_name_string.empty() ? "<anonymous>" : attribute_name) +
+        " does not exist for array " + array_schema->array_uri().to_string());
   }
 
-  tiledb_string_t* enumeration_name_inner;
-  capi_return_t getenmr = tiledb_attribute_get_enumeration_name(
-      ctx, attribute, &enumeration_name_inner);
-  if (tiledb_status(getenmr) != TILEDB_OK) {
-    return getenmr;
+  auto enumeration_name = found_attr->get_enumeration_name();
+  if (!enumeration_name.has_value()) {
+    *enumeration = nullptr;
+    return TILEDB_OK;
   }
 
-  std::string enumeration_name(enumeration_name_inner->view());
-  return api_entry_with_context<
-      tiledb::api::tiledb_array_schema_get_enumeration_from_name>(
-      ctx, array_schema, enumeration_name.c_str(), enumeration);
+  array_schema->load_enumeration(ctx, enumeration_name->c_str());
+
+  auto ptr = array_schema->get_enumeration(enumeration_name->c_str());
+  *enumeration = tiledb_enumeration_handle_t::make_handle(ptr);
+
+  return TILEDB_OK;
 }
 
 capi_return_t tiledb_array_schema_add_enumeration(

tiledb/api/c_api/array_schema/array_schema_api_experimental.h

@@ -68,7 +68,7 @@ TILEDB_EXPORT capi_return_t tiledb_array_schema_timestamp_range(
     uint64_t* hi) TILEDB_NOEXCEPT;
 
 /**
- * Retrieves an enumeration from an array schema using the enumeration name,
+ * Retrieves an enumeration from an array schema using the enumeration name.
  *
  * **Example:**
  *