Query: we don't know how to lift join on QSRE projecting a single column

[maumar]

from g in ctx.Gears
join inner in (
	from g2 in ctx.Gears
	select g2.Nickname
	) on g.Nickname equals inner
select g;

produces the following query plan:

(QueryContext queryContext) => IEnumerable<Gear> _InterceptExceptions(
    source: IEnumerable<Gear> _Select(
        source: IEnumerable<TransparentIdentifier<Gear, string>> _Join(
            outer: IEnumerable<Gear> _ShapedQuery(
                queryContext: queryContext, 
                shaperCommandContext: SelectExpression: 
                    SELECT [g].[Nickname], [g].[SquadId], [g].[AssignedCityName], [g].[CityOrBirthName], [g].[Discriminator], [g].[FullName], [g].[HasSoulPatch], [g].[LeaderNickname], [g].[LeaderSquadId], [g].[Rank]
                    FROM [Gears] AS [g]
                    WHERE [g].[Discriminator] IN (N'Officer', N'Gear'), 
                shaper: BufferedEntityShaper<Gear>), 
            inner: IEnumerable<string> _ShapedQuery(
                queryContext: queryContext, 
                shaperCommandContext: SelectExpression: 
                    SELECT [t].[Nickname]
                    FROM (
                        SELECT [g2].[Nickname]
                        FROM [Gears] AS [g2]
                        WHERE [g2].[Discriminator] IN (N'Officer', N'Gear')
                    ) AS [t], 
                shaper: (TypedProjectionShaper<ValueBufferShaper, ValueBuffer, string>
                materializer: (ValueBuffer g2) => string TryReadValue(g2, 0, Gear.Nickname))), 
            outerKeySelector: (Gear g) => g.Nickname, 
            innerKeySelector: (string inner) => inner, 
            resultSelector: (Gear g | string inner) => TransparentIdentifier<Gear, string> CreateTransparentIdentifier(
                outer: g, 
                inner: inner)), 
        selector: (TransparentIdentifier<Gear, string> t0) => t0.Outer), 
    contextType: TestModels.GearsOfWarModel.GearsOfWarContext, 
    logger: DiagnosticsLogger<Query>, 
    queryContext: queryContext)

However we are perfectly capable of translating very similar query, that projects single property wrapped in anonymous type:

from g in ctx.Gears
join inner in (
     from g2 in ctx.Gears
     select new { g2.Nickname }
     ) on g.Nickname equals inner.Nickname
select g;

produces:

(QueryContext queryContext) => IEnumerable<Gear> _InterceptExceptions(
    source: IEnumerable<Gear> _ShapedQuery(
        queryContext: queryContext, 
        shaperCommandContext: SelectExpression: 
            SELECT [g].[Nickname], [g].[SquadId], [g].[AssignedCityName], [g].[CityOrBirthName], [g].[Discriminator], [g].[FullName], [g].[HasSoulPatch], [g].[LeaderNickname], [g].[LeaderSquadId], [g].[Rank], [t].[Nickname]
            FROM [Gears] AS [g]
            INNER JOIN (
                SELECT [g2].[Nickname]
                FROM [Gears] AS [g2]
                WHERE [g2].[Discriminator] IN (N'Officer', N'Gear')
            ) AS [t] ON [g].[Nickname] = [t].[Nickname]
            WHERE [g].[Discriminator] IN (N'Officer', N'Gear'), 
        shaper: (BufferedOffsetEntityShaper<Gear>
        materializer: (TransparentIdentifier<Gear, <>f__AnonymousType227<string>> t0) => t0.Outer)), 
    contextType: TestModels.GearsOfWarModel.GearsOfWarContext, 
    logger: DiagnosticsLogger<Query>, 
    queryContext: queryContext)

[maumar]

verified this issue has been fixed in 3.0