TableValuedAlias generation fixes

Fixed bug in newly implemented
:paramref:`.FunctionElement.table_valued.joins_implicitly` feature where
the parameter would not automatically propagate from the original
:class:`.TableValuedAlias` object to the secondary object produced when
calling upon :meth:`.TableValuedAlias.render_derived` or
:meth:`.TableValuedAlias.alias`.

Additionally repaired these issues in :class:`.TableValuedAlias`:

* repaired a potential memory issue which could occur when
repeatedly calling :meth:`.TableValuedAlias.render_derived` against
successive copies of the same object (for .alias(), we currently
have to still continue chaining from the previous element.  not sure
if this can be improved but this is standard behavior for .alias()
elsewhere)
* repaired issue where the individual element types would be lost when
calling upon :meth:`.TableValuedAlias.render_derived` or
:meth:`.TableValuedAlias.alias`.

Fixes: #7890
Change-Id: Ie5120c7ff1e5c1bba5aaf77c782a51c637860208

1 files changed, 13 insertions, 0 deletions

diff --git a/test/aaa_profiling/test_memusage.py b/test/aaa_profiling/test_memusage.py
index f084eac2c..24cc0b99b 100644
--- a/test/aaa_profiling/test_memusage.py
+++ b/test/aaa_profiling/test_memusage.py
@@ -6,6 +6,7 @@ import weakref
 
 import sqlalchemy as sa
 from sqlalchemy import ForeignKey
+from sqlalchemy import func
 from sqlalchemy import inspect
 from sqlalchemy import Integer
 from sqlalchemy import MetaData
@@ -359,6 +360,18 @@ class MemUsageTest(EnsureZeroed):
 
         go()
 
+    def test_tv_render_derived(self):
+        root_expr = func.some_fn().table_valued()
+        expr = root_expr
+
+        @profile_memory()
+        def go():
+            nonlocal expr
+
+            expr = expr.render_derived()
+
+        go()
+
 
 @testing.add_to_marker.memory_intensive
 class MemUsageWBackendTest(fixtures.MappedTest, EnsureZeroed):