Query: compilation error for query with Except projecting a constant

[maumar]

query:

ctx.Customers.Except(ctx.Customers).Select(e => 1)

exception:

Expression of type 'System.Collections.Generic.IEnumerable`1[System.Int32]' cannot be used for parameter of type 'System.Collections.Generic.IEnumerable`1[System.Object]' of method 'System.Collections.Generic.IEnumerable`1[System.Object] Except[Object](System.Collections.Generic.IEnumerable`1[System.Object], System.Collections.Generic.IEnumerable`1[System.Object])'
	at System.Linq.Expressions.Expression.ValidateOneArgument(MethodBase method, ExpressionType nodeKind, Expression arg, ParameterInfo pi)
	at System.Linq.Expressions.Expression.Call(MethodInfo method, Expression arg0, Expression arg1)
	at Microsoft.EntityFrameworkCore.Query.ResultOperatorHandler.HandleSetOperation(EntityQueryModelVisitor entityQueryModelVisitor, Expression secondSource, MethodInfo setMethodInfo)
	at Microsoft.EntityFrameworkCore.Query.ResultOperatorHandler.HandleExcept(EntityQueryModelVisitor entityQueryModelVisitor, ExceptResultOperator exceptResultOperator)
	at Microsoft.EntityFrameworkCore.Query.ResultOperatorHandler.<>c.<.cctor>b__33_9(EntityQueryModelVisitor v, ResultOperatorBase r, QueryModel __)
	at Microsoft.EntityFrameworkCore.Query.ResultOperatorHandler.HandleResultOperator(EntityQueryModelVisitor entityQueryModelVisitor, ResultOperatorBase resultOperator, QueryModel queryModel)
	at Microsoft.EntityFrameworkCore.Query.Internal.RelationalResultOperatorHandler.HandlerContext.EvalOnClient(Boolean requiresClientResultOperator)
	at Microsoft.EntityFrameworkCore.Query.Internal.RelationalResultOperatorHandler.HandleResultOperator(EntityQueryModelVisitor entityQueryModelVisitor, ResultOperatorBase resultOperator, QueryModel queryModel)
	at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitResultOperator(ResultOperatorBase resultOperator, QueryModel queryModel, Int32 index)
	at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitResultOperator(ResultOperatorBase resultOperator, QueryModel queryModel, Int32 index)
	at Remotion.Linq.Clauses.ResultOperatorBase.Accept(IQueryModelVisitor visitor, QueryModel queryModel, Int32 index)
	at Remotion.Linq.QueryModelVisitorBase.VisitResultOperators(ObservableCollection`1 resultOperators, QueryModel queryModel)
	at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
	at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
	at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
	at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateQueryExecutor[TResult](QueryModel queryModel)
	at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](QueryModel queryModel)
	--- End of stack trace from previous location where exception was thrown ---
	at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
	at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](Expression query, IQueryModelGenerator queryModelGenerator, IDatabase database, IDiagnosticsLogger`1 logger, Type contextType)
	at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass13_0`1.<Execute>b__0()
	at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
	at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
	at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
	at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.Execute[TResult](Expression expression)
	at Remotion.Linq.QueryableBase`1.GetEnumerator()
	at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
	at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
	at Microsoft.EntityFrameworkCore.Query.SimpleQueryTestBase`1.Except_simple(Boolean isAsync)
	at Microsoft.EntityFrameworkCore.Query.SimpleQuerySqlServerTest.Except_simple(Boolean isAsync)

[roji]

This issue disappears with the new implementation of set operations (PR #16249).

[roji]

The original issue disappears but the test now fails with:

System.InvalidCastException : Unable to cast object of type 'System.String' to type 'System.Int32'.
   at Microsoft.Data.SqlClient.SqlBuffer.get_Int32()
   at Microsoft.Data.SqlClient.SqlDataReader.GetInt32(Int32 i)
   at Microsoft.EntityFrameworkCore.Relational.Query.Pipeline.RelationalShapedQueryCompilingExpressionVisitor.QueryingEnumerable`1.Enumerator.MoveNext() in /home/roji/projects/EFCore/src/EFCore.Relational/Query/Pipeline/QueryingEnumerable.cs:line 143
   at System.Collections.Generic.LargeArrayBuilder`1.AddRange(IEnumerable`1 items)
   at System.Collections.Generic.EnumerableHelpers.ToArray[T](IEnumerable`1 source)
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Microsoft.EntityFrameworkCore.Query.SimpleQueryTestBase`1.Union_Select_constant() in /home/roji/projects/EFCore/test/EFCore.Specification.Tests/Query/SimpleQueryTestBase.SetOperations.cs:line 225
   at Microsoft.EntityFrameworkCore.Query.SimpleQuerySqlServerTest.Union_Select_constant() in /home/roji/projects/EFCore/test/EFCore.SqlServer.FunctionalTests/Query/SimpleQuerySqlServerTest.SetOperations.cs:line 211

[smitpatel]

Check the shaper expression before compiling into QueryingEnumerable. Possible cause of error is unexpected column getting projected and mangling index.

[roji]

Verified and this no longer fails.