From 120347aad15fac4a54e16aa60e0e5b3b6b3995c4 Mon Sep 17 00:00:00 2001
From: Oliver Rice <github@oliverrice.com>
Date: Sat, 13 Feb 2021 14:21:55 -0500
Subject: [PATCH] Support legacy select(<iterable>) in addition to
 select(<list>) in v1.4

Fixed regression where use of an arbitrary iterable with the
:func:`_sql.select` function was not working, outside of plain lists. The
forwards/backwards compatibility logic here now checks for a wider range of
incoming "iterable" types including that a ``.c`` collection from a
selectable can be passed directly. Pull request compliments of Oliver Rice.

Fixes: #5935
Closes: #5936
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5936
Pull-request-sha: 575ab3e7df30fc8da03752d102c8eeb6cb3a3e3d

Change-Id: Icd972f1078d9ea96c47a64133079f00d9b0a66f3
---
 doc/build/changelog/unreleased_14/5935.rst |  9 +++++++++
 lib/sqlalchemy/sql/selectable.py           |  6 +++++-
 test/sql/test_deprecations.py              | 10 ++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 doc/build/changelog/unreleased_14/5935.rst

diff --git a/doc/build/changelog/unreleased_14/5935.rst b/doc/build/changelog/unreleased_14/5935.rst
new file mode 100644
index 0000000000..f7d06301a9
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/5935.rst
@@ -0,0 +1,9 @@
+.. change::
+    :tags: bug, sql
+    :tickets: 5935
+
+    Fixed regression where use of an arbitrary iterable with the
+    :func:`_sql.select` function was not working, outside of plain lists. The
+    forwards/backwards compatibility logic here now checks for a wider range of
+    incoming "iterable" types including that a ``.c`` collection from a
+    selectable can be passed directly. Pull request compliments of Oliver Rice.
diff --git a/lib/sqlalchemy/sql/selectable.py b/lib/sqlalchemy/sql/selectable.py
index 23fdf7e12b..ee2c4dafc5 100644
--- a/lib/sqlalchemy/sql/selectable.py
+++ b/lib/sqlalchemy/sql/selectable.py
@@ -4861,7 +4861,11 @@ class Select(
           constructs as given, as well as ORM-mapped classes.
 
         """
-        if (args and isinstance(args[0], list)) or kw:
+        if (
+            args
+            and hasattr(args[0], "__iter__")
+            and not isinstance(args[0], util.string_types + (ClauseElement,))
+        ) or kw:
             return cls.create_legacy_select(*args, **kw)
         else:
             return cls._create_future_select(*args)
diff --git a/test/sql/test_deprecations.py b/test/sql/test_deprecations.py
index 35633a1a36..1e5b1b995f 100644
--- a/test/sql/test_deprecations.py
+++ b/test/sql/test_deprecations.py
@@ -437,6 +437,16 @@ class SelectableTest(fixtures.TestBase, AssertsCompiledSQL):
             stmt = select([column("q")])
         self.assert_compile(stmt, "SELECT q")
 
+    def test_select_column_collection_argument(self):
+        t1 = table("t1", column("q"))
+
+        with testing.expect_deprecated_20(
+            r"The legacy calling style of select\(\) is deprecated "
+            "and will be removed in SQLAlchemy 2.0"
+        ):
+            stmt = select(t1.c)
+        self.assert_compile(stmt, "SELECT t1.q FROM t1")
+
     def test_select_kw_argument(self):
 
         with testing.expect_deprecated_20(
-- 
2.47.2