Free variables are no longer translated to bind variables if they are defined by the type

[cello99d]

public class Blog
	{
		BloggingContext _ctx;
		public Blog(BloggingContext ctx) {
			_ctx = ctx;
		}

		public int BlogId { get; set; }
		public string Url { get; set; }
		public int Rating { get; set; }

		private Blog meField;
		private Blog This => this;
		private Blog MeFieldGet { get { return meField; } }
		private static string UrlGet() { return "Fo' and 1=1 and 'o"; }
		public int CountOthers() {
			var me = this;
			meField = this;
			int s1 = _ctx.Blogs.Where(b => b != this).Count();
			int s2 = _ctx.Blogs.Where(b => b != This).Count();
			int s3 = _ctx.Blogs.Where(b => b != me).Count();
			int s4 = _ctx.Blogs.Where(b => b != MeFieldGet).Count();
			int s5 = _ctx.Blogs.Where(b => b != meField).Count();
			return s1;
		}
	}

Using EF Core 2.2 the statements s2, s3, s4, s5 were translated to
SELECT COUNT(*) FROM "Blogs" AS "b"WHERE ("b"."BlogId" <> @__entity_equality_me_0_BlogId) OR @__entity_equality_me_0_BlogId IS NULL

Ef Core 3 translates s1, s2, s4, s5 to:
SELECT COUNT(*) FROM "Blogs" AS "b" WHERE "b"."BlogId" <> 99

Only acces to the local variable "me" in s3 ist still using a bind variable.
The edge case s1 was not translated as I would excpect in EF Core 2.2, see Query: Number is written into SQL Command Text instead of being a parameter when using 'this'

Using literals instead of bind variables causes performance problems in Oracle because it destroys the statement cache. I don't know about other brands but I guess its the same problem too.
Program.zip

[smitpatel]

Duplicate of #17172

Generated SQL in latest daily builds (Entity Framework Core 3.0.0-rc1.19429.10)

SELECT COUNT(*)
FROM [Blogs] AS [b]
WHERE [b].[BlogId] <> 99

exec sp_executesql N'SELECT COUNT(*)
FROM [Blogs] AS [b]
WHERE ([b].[BlogId] <> @__entity_equality_This_0_BlogId) OR @__entity_equality_This_0_BlogId IS NULL',N'@__entity_equality_This_0_BlogId int',@__entity_equality_This_0_BlogId=99

exec sp_executesql N'SELECT COUNT(*)
FROM [Blogs] AS [b]
WHERE ([b].[BlogId] <> @__entity_equality_me_0_BlogId) OR @__entity_equality_me_0_BlogId IS NULL',N'@__entity_equality_me_0_BlogId int',@__entity_equality_me_0_BlogId=99

exec sp_executesql N'SELECT COUNT(*)
FROM [Blogs] AS [b]
WHERE ([b].[BlogId] <> @__entity_equality_MeFieldGet_0_BlogId) OR @__entity_equality_MeFieldGet_0_BlogId IS NULL',N'@__entity_equality_MeFieldGet_0_BlogId int',@__entity_equality_MeFieldGet_0_BlogId=99

exec sp_executesql N'SELECT COUNT(*)
FROM [Blogs] AS [b]
WHERE ([b].[BlogId] <> @__entity_equality_meField_0_BlogId) OR @__entity_equality_meField_0_BlogId IS NULL',N'@__entity_equality_meField_0_BlogId int',@__entity_equality_meField_0_BlogId=99
``

[cello99d]

Is there any chance that query s1 could also be translated to using a bind variable?

[smitpatel]

@cello99d - It is not easy to do that. Essentially we only see a constant in Expression tree. The only way we would make it parameter is to convert every constant ever appeared as a parameter. Which may not be desired behavior in all cases.