Fix generate_schema_name macro for multiple args

Add repeat flag to warn_or_error to suppress duplicate warnings
Add a warning if a user's macro does not take a second argument

core/dbt/exceptions.py

@@ -652,10 +652,16 @@ def raise_not_implemented(msg):
     raise NotImplementedException(msg)
 
 
-def warn_or_error(msg, node=None, log_fmt=None):
+_REPEAT_MESSAGE_CACHE = set()
+
+
+def warn_or_error(msg, node=None, log_fmt=None, repeat=True):
     if dbt.flags.WARN_ERROR:
         raise_compiler_error(msg, node)
     else:
+        if not repeat and msg in _REPEAT_MESSAGE_CACHE:
+            return
+        _REPEAT_MESSAGE_CACHE.add(msg)
         if log_fmt is not None:
             msg = log_fmt.format(msg)
         logger.warning(msg)

core/dbt/parser/base.py

@@ -209,7 +209,21 @@ def _update_parsed_node_info(self, parsed_node, config):
         # definition, not the current package
         schema_override = config.config.get('schema')
         get_schema = self.get_schema_func()
-        parsed_node.schema = get_schema(schema_override, parsed_node).strip()
+        try:
+            schema = get_schema(schema_override, parsed_node)
+        except dbt.exceptions.CompilationException as exc:
+            too_many_args = (
+                "macro 'dbt_macro__generate_schema_name' takes not more than "
+                "1 argument(s)"
+            )
+            if too_many_args not in str(exc):
+                raise
+            msg = ('The generate_schema_name macro does not accept a second '
+                   'argument. This form is deprecated as of 0.14.0')
+            dbt.exceptions.warn_or_error(msg, node=parsed_node, repeat=False,
+                                         log_fmt='WARNING: {}')
+            schema = get_schema(schema_override)
+        parsed_node.schema = schema.strip()
 
         alias_override = config.config.get('alias')
         get_alias = self.get_alias_func()