change the POSTCOMPILE/ SCHEMA symbols to not conflict w mssql quoting

Adjusted the compiler's generation of "post compile" symbols including
those used for "expanding IN" as well as for the "schema translate map" to
not be based directly on plain bracketed strings with underscores, as this
conflicts directly with SQL Server's quoting format of also using brackets,
which produces false matches when the compiler replaces "post compile" and
"schema translate" symbols. The issue created easy to reproduce examples
both with the :meth:`.Inspector.get_schema_names` method when used in
conjunction with the
:paramref:`_engine.Connection.execution_options.schema_translate_map`
feature, as well in the unlikely case that a symbol overlapping with the
internal name "POSTCOMPILE" would be used with a feature like "expanding
in".

Fixes: #7300
Change-Id: I6255c850b140522a4aba95085216d0bca18ce230

2 files changed, 22 insertions, 5 deletions

diff --git a/doc/build/changelog/unreleased_14/7300.rst b/doc/build/changelog/unreleased_14/7300.rst
new file mode 100644
index 000000000..d9061af09
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/7300.rst
@@ -0,0 +1,17 @@
+.. change::
+    :tags: mssql, bug
+    :tickets: 7300
+
+    Adjusted the compiler's generation of "post compile" symbols including
+    those used for "expanding IN" as well as for the "schema translate map" to
+    not be based directly on plain bracketed strings with underscores, as this
+    conflicts directly with SQL Server's quoting format of also using brackets,
+    which produces false matches when the compiler replaces "post compile" and
+    "schema translate" symbols. The issue created easy to reproduce examples
+    both with the :meth:`.Inspector.get_schema_names` method when used in
+    conjunction with the
+    :paramref:`_engine.Connection.execution_options.schema_translate_map`
+    feature, as well in the unlikely case that a symbol overlapping with the
+    internal name "POSTCOMPILE" would be used with a feature like "expanding
+    in".
+
diff --git a/doc/build/core/operators.rst b/doc/build/core/operators.rst
index 8d962560d..d119db1e0 100644
--- a/doc/build/core/operators.rst
+++ b/doc/build/core/operators.rst
@@ -172,9 +172,9 @@ values to the :meth:`_sql.ColumnOperators.in_` method::
 
 
     >>> print(column('x').in_([1, 2, 3]))
-    x IN ([POSTCOMPILE_x_1])
+    x IN (__[POSTCOMPILE_x_1])
 
-The special bound form ``POSTCOMPILE`` is rendered into individual parameters
+The special bound form ``__[POSTCOMPILE`` is rendered into individual parameters
 at execution time, illustrated below:
 
 .. sourcecode:: pycon+sql
@@ -212,12 +212,12 @@ NOT IN
 "NOT IN" is available via the :meth:`_sql.ColumnOperators.not_in` operator::
 
     >>> print(column('x').not_in([1, 2, 3]))
-    (x NOT IN ([POSTCOMPILE_x_1]))
+    (x NOT IN (__[POSTCOMPILE_x_1]))
 
 This is typically more easily available by negating with the ``~`` operator::
 
     >>> print(~column('x').in_([1, 2, 3]))
-    (x NOT IN ([POSTCOMPILE_x_1]))
+    (x NOT IN (__[POSTCOMPILE_x_1]))
 
 Tuple IN Expressions
 ~~~~~~~~~~~~~~~~~~~~
@@ -232,7 +232,7 @@ then receives a list of tuples::
     >>> tup = tuple_(column('x', Integer), column('y', Integer))
     >>> expr = tup.in_([(1, 2), (3, 4)])
     >>> print(expr)
-    (x, y) IN ([POSTCOMPILE_param_1])
+    (x, y) IN (__[POSTCOMPILE_param_1])
 
 To illustrate the parameters rendered: