SERVER-61802: Create changeStreamOptions cluster server parameter

5 files changed, 50 insertions, 15 deletions

diff --git a/buildscripts/idl/idl/binder.py b/buildscripts/idl/idl/binder.py
index 1b11d1af4f7..1511b6c1b07 100644
--- a/buildscripts/idl/idl/binder.py
+++ b/buildscripts/idl/idl/binder.py
@@ -438,7 +438,7 @@ def _bind_struct_field(ctxt, ast_field, idl_type):
     ast_field.type = _bind_struct_type(struct)
     ast_field.type.is_array = isinstance(idl_type, syntax.ArrayType)
 
-    _validate_field_of_type_struct(ctxt, ast_field)
+    _validate_default_of_type_struct(ctxt, ast_field)
 
 
 def _bind_variant_field(ctxt, ast_field, idl_type):
@@ -747,11 +747,11 @@ def _validate_ignored_field(ctxt, field):
         ctxt.add_ignored_field_must_be_empty_error(field, field.name, "default")
 
 
-def _validate_field_of_type_struct(ctxt, field):
+def _validate_default_of_type_struct(ctxt, field):
     # type: (errors.ParserContext, Union[syntax.Field, ast.Field]) -> None
-    """Validate that for fields with a type of struct, no other properties are set."""
-    if field.default is not None:
-        ctxt.add_struct_field_must_be_empty_error(field, field.name, "default")
+    """Validate that for fields with a type of struct, the only default permitted is true, which causes it to be default-constructed."""
+    if (field.default is not None) and (field.default != "true"):
+        ctxt.add_struct_default_must_be_true_or_empty_error(field, field.name)
 
 
 def _validate_variant_type(ctxt, syntax_symbol, field):
diff --git a/buildscripts/idl/idl/errors.py b/buildscripts/idl/idl/errors.py
index f1c387df2f7..4efd18797f9 100644
--- a/buildscripts/idl/idl/errors.py
+++ b/buildscripts/idl/idl/errors.py
@@ -63,7 +63,7 @@ ERROR_ID_BAD_BSON_BINDATA_SUBTYPE_TYPE = "ID0015"
 ERROR_ID_BAD_BSON_BINDATA_SUBTYPE_VALUE = "ID0016"
 ERROR_ID_NO_STRINGDATA = "ID0017"
 ERROR_ID_FIELD_MUST_BE_EMPTY_FOR_IGNORED = "ID0018"
-ERROR_ID_FIELD_MUST_BE_EMPTY_FOR_STRUCT = "ID0019"
+ERROR_ID_DEFAULT_MUST_BE_TRUE_OR_EMPTY_FOR_STRUCT = "ID0019"
 ERROR_ID_CUSTOM_SCALAR_SERIALIZATION_NOT_SUPPORTED = "ID0020"
 ERROR_ID_BAD_ANY_TYPE_USE = "ID0021"
 ERROR_ID_BAD_NUMERIC_CPP_TYPE = "ID0022"
@@ -462,14 +462,13 @@ class ParserContext(object):
             ("Field '%s' cannot contain a value for property '%s' when a field is marked as ignored"
              ) % (name, field_name))
 
-    def add_struct_field_must_be_empty_error(self, location, name, field_name):
-        # type: (common.SourceLocation, str, str) -> None
-        """Add an error about field must be empty for fields of type struct."""
+    def add_struct_default_must_be_true_or_empty_error(self, location, name):
+        # type: (common.SourceLocation, str) -> None
+        """Add an error about default must be True or empty for fields of type struct."""
         # pylint: disable=invalid-name
-        self._add_error(
-            location, ERROR_ID_FIELD_MUST_BE_EMPTY_FOR_STRUCT,
-            ("Field '%s' cannot contain a value for property '%s' when a field's type is a struct")
-            % (name, field_name))
+        self._add_error(location, ERROR_ID_DEFAULT_MUST_BE_TRUE_OR_EMPTY_FOR_STRUCT, (
+            "Field '%s' can only contain value 'true' for property 'default' when a field's type is a struct"
+        ) % (name))
 
     def add_not_custom_scalar_serialization_not_supported_error(self, location, ast_type,
                                                                 ast_parent, bson_type_name):
diff --git a/buildscripts/idl/idl/generator.py b/buildscripts/idl/idl/generator.py
index 6c3bc4948cc..d8b38d51a0c 100644
--- a/buildscripts/idl/idl/generator.py
+++ b/buildscripts/idl/idl/generator.py
@@ -617,10 +617,14 @@ class _CppHeaderFileWriter(_CppFileWriterBase):
         member_type = cpp_type_info.get_storage_type()
         member_name = _get_field_member_name(field)
 
+        # Struct fields are allowed to specify default: true so that the member gets default-
+        # constructed.
         if field.default and not field.constructed:
             if field.type.is_enum:
                 self._writer.write_line('%s %s{%s::%s};' % (member_type, member_name,
                                                             field.type.cpp_type, field.default))
+            elif field.type.is_struct:
+                self._writer.write_line('%s %s;' % (member_type, member_name))
             else:
                 self._writer.write_line('%s %s{%s};' % (member_type, member_name, field.default))
         else:
diff --git a/buildscripts/idl/idl_check_compatibility.py b/buildscripts/idl/idl_check_compatibility.py
index d34dbc83409..9aab17079f3 100644
--- a/buildscripts/idl/idl_check_compatibility.py
+++ b/buildscripts/idl/idl_check_compatibility.py
@@ -191,6 +191,15 @@ SKIPPED_FILES = [
     "nsICollation.idl", "nsIStringBundle.idl", "nsIScriptableUConv.idl", "nsITextToSubURI.idl"
 ]
 
+# Do not add commands that were visible to users in previously released versions.
+IGNORE_COMMANDS_LIST: List[str] = [
+    # The following commands were released behind a feature flag in 5.3 but were shelved in
+    # favor of getClusterParameter and setClusterParameter. Since the feature flag was not enabled
+    # in 5.3, they were effectively unusable and so can be safely removed from the strict API.
+    'getChangeStreamOptions',
+    'setChangeStreamOptions',
+]
+
 
 class FieldCompatibility:
     """Information about a Field to check compatibility."""
@@ -1193,6 +1202,12 @@ def check_compatibility(old_idl_dir: str, new_idl_dir: str, old_import_directori
                     if old_cmd.api_version == "" or old_cmd.imported:
                         continue
 
+                    # Ignore select commands that were removed after being added to the strict API.
+                    # Only commands that were never visible to the end-user in previous releases
+                    # (i.e., hidden behind a feature flag) should be allowed here.
+                    if old_cmd.command_name in IGNORE_COMMANDS_LIST:
+                        continue
+
                     if old_cmd.api_version != "1":
                         # We're not ready to handle future API versions yet.
                         ctxt.add_command_invalid_api_version_error(
diff --git a/buildscripts/idl/tests/test_binder.py b/buildscripts/idl/tests/test_binder.py
index 2ce3dd45559..b52c755e34b 100644
--- a/buildscripts/idl/tests/test_binder.py
+++ b/buildscripts/idl/tests/test_binder.py
@@ -942,6 +942,23 @@ class TestBinder(testcase.IDLTestcase):
                             always_serialize: true
             """))
 
+        # Test field of a struct type with default=true
+        self.assert_bind(test_preamble + textwrap.dedent("""
+            structs:
+                foo:
+                    description: foo
+                    fields:
+                        field1: string
+
+                bar:
+                    description: foo
+                    fields:
+                        field2:
+                            type: foo
+                            default: true
+
+            """))
+
     def test_field_negative(self):
         # type: () -> None
         """Negative field tests."""
@@ -964,7 +981,7 @@ class TestBinder(testcase.IDLTestcase):
                 bindata_subtype: uuid
         """)
 
-        # Test field of a struct type with a default
+        # Test field of a struct type with a non-true default
         self.assert_bind_fail(
             test_preamble + textwrap.dedent("""
             structs:
@@ -980,7 +997,7 @@ class TestBinder(testcase.IDLTestcase):
                             type: foo
                             default: foo
 
-            """), idl.errors.ERROR_ID_FIELD_MUST_BE_EMPTY_FOR_STRUCT)
+            """), idl.errors.ERROR_ID_DEFAULT_MUST_BE_TRUE_OR_EMPTY_FOR_STRUCT)
 
         # Test array as field name
         self.assert_bind_fail(