Query: Null semantics :: we are overzealous in applying "full" null expansion in some cases

[maumar]

ctx.Customers.Where(c => c.Name != "Foo" && c.NullableInt == 5);

will get expanded into:

ctx.Customers.Where(c => (c.Name != "Foo" || c.Name == null) && (c.NullableInt == 5 && c.NullableInt != null);

while first part, i.e. (c.Name != "Foo" || c.Name == null) is necessary, the second expansion is redundant in this case.

In some cases it is beneficial to expand all "leaf" nodes using full expansion, e.g.

ctx.Customers.Where(c => (c.Name != "Foo") ==  (c.NullableInt == 5));

but if the top level operand is different than == and !=, it is not needed and we should only apply simplified null expansion for the second term, which in this case is leave it as is

[smitpatel]

@maumar - Is this valid for new query pipeline?

[maumar]

we don't have the full/simplified null semantics in the new pipeline, so currently this issue is not applicable. However we might re-introduce it given the perf considerations raised in #17543