Coalesce with not equal unexpected SQL translation

[ickers]

Evaluation of simple LINQ expression involving null coalescing operator and subsequent primitive not-equals comparison within predicate returns an unexpected result set.

Given data saved:

context.Data.Add( new Data { Name = "HasTestId", TestId = 123 } );
context.Data.Add( new Data { Name = "ZeroTestId", TestId = 0 } );
context.Data.Add( new Data { Name = "NullTestId", TestId = null } );
context.SaveChanges( );

the LINQ

context.Data.Where( o => (o.TestId ?? 0) != 0 ).Select( o => o.Name )

evaluates to the result [ "HasTestId", "NullTestId" ] instead of the expected [ "HasTestId" ]. This is because the above LINQ is compiled by EF Core to the SQL:

SELECT "o"."Name"
FROM "Data" AS "o"
WHERE (COALESCE("o"."TestId", 0) <> 0) OR "o"."TestId" IS NULL

The extraneous OR "o"."TestId" IS NULL added to the WHERE clause seems incorrect IMHO. Interestingly, by switching the predicate from != to == the LINQ evaluates to the expected result [ "ZeroTestId", "NullTestId" ].

Steps to reproduce

Clone repro project at ickers/ef-core-coalesce-not-equal-query@6d5af16 (multi-targeted project for netcoreapp2.0/ef-core-2.0.3, netcoreapp2.1/ef-core-2.1.11, netcoreapp2.2/ef-core-2.2.6 - issue is reproducible in all three runtime/EF Core versions).

Further technical details

EF Core version: 2.2.6, 2.1.11, 2.0.3
Database Provider: Microsoft.EntityFrameworkCore.Sqlite (originally observed with Microsoft.EntityFrameworkCore.SqlServer)
Operating system: Linux Mint 18
IDE: VS Code 1.36 (originally observed with Visual Studio 2017 15.4)

[maumar]

Looks like Bug in null semantics

[maumar]

fixed in dd92ba3