call _compiler_dispatch for merge_into and copy_into clauses

Author: sjhewitt

src/snowflake/sqlalchemy/base.py

@@ -158,8 +158,11 @@ def visit_merge_into(self, merge_into, **kw):
         clauses = " ".join(
             clause._compiler_dispatch(self, **kw) for clause in merge_into.clauses
         )
+        target = merge_into.target._compiler_dispatch(self, asfrom=True, **kw)
+        source = merge_into.source._compiler_dispatch(self, asfrom=True, **kw)
+        on = merge_into.on._compiler_dispatch(self, **kw)
         return (
-            f"MERGE INTO {merge_into.target} USING {merge_into.source} ON {merge_into.on}"
+            f"MERGE INTO {target} USING {source} ON {on}"
             + (" " + clauses if clauses else "")
         )
 
@@ -207,11 +210,7 @@ def visit_copy_into(self, copy_into, **kw):
             formatter = copy_into.formatter._compiler_dispatch(self, **kw)
         else:
             formatter = ""
-        into = (
-            copy_into.into
-            if isinstance(copy_into.into, Table)
-            else copy_into.into._compiler_dispatch(self, **kw)
-        )
+        into = copy_into.into._compiler_dispatch(self, asfrom=True, **kw)
         from_ = None
         if isinstance(copy_into.from_, Table):
             from_ = copy_into.from_