Merge "Render NULL for bindparam w/ None value/literal_binds, warn"

2 files changed, 13 insertions, 4 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index aabc257eb..353de2c48 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -2055,6 +2055,7 @@ class SQLCompiler(Compiled):
         _in_binary = kw.get("_in_binary", False)
 
         kw["_in_binary"] = True
+        kw["_binary_op"] = binary.operator
         text = (
             binary.left._compiler_dispatch(
                 self, eager_grouping=eager_grouping, **kw
@@ -2306,10 +2307,15 @@ class SQLCompiler(Compiled):
             value = render_literal_value
         else:
             if bindparam.value is None and bindparam.callable is None:
-                raise exc.CompileError(
-                    "Bind parameter '%s' without a "
-                    "renderable value not allowed here." % bindparam.key
-                )
+                op = kw.get("_binary_op", None)
+                if op and op not in (operators.is_, operators.is_not):
+                    util.warn_limited(
+                        "Bound parameter '%s' rendering literal NULL in a SQL "
+                        "expression; comparisons to NULL should not use "
+                        "operators outside of 'is' or 'is not'",
+                        (bindparam.key,),
+                    )
+                return self.process(sqltypes.NULLTYPE, **kw)
             value = bindparam.effective_value
 
         if bindparam.expanding:
diff --git a/lib/sqlalchemy/testing/assertions.py b/lib/sqlalchemy/testing/assertions.py
index f2ed91b79..79125e1f1 100644
--- a/lib/sqlalchemy/testing/assertions.py
+++ b/lib/sqlalchemy/testing/assertions.py
@@ -388,6 +388,7 @@ class AssertsCompiledSQL(object):
         check_prefetch=None,
         use_default_dialect=False,
         allow_dialect_select=False,
+        supports_default_values=True,
         literal_binds=False,
         render_postcompile=False,
         schema_translate_map=None,
@@ -396,6 +397,7 @@ class AssertsCompiledSQL(object):
     ):
         if use_default_dialect:
             dialect = default.DefaultDialect()
+            dialect.supports_default_values = supports_default_values
         elif allow_dialect_select:
             dialect = None
         else:
@@ -406,6 +408,7 @@ class AssertsCompiledSQL(object):
                 dialect = config.db.dialect
             elif dialect == "default":
                 dialect = default.DefaultDialect()
+                dialect.supports_default_values = supports_default_values
             elif dialect == "default_enhanced":
                 dialect = default.StrCompileDialect()
             elif isinstance(dialect, util.string_types):