LINQ: Select Clause

In [11.18.3.6 Select clauses](https://github.com/dotnet/csharpstandard/blob/draft-v7/standard/expressions.md#111836-select-clauses) the spec says that

```csharp
from c in customers.Where(c => c.City == "London")
select c
```

is translated to

```csharp
(customers).Where(c => c.City == "London")
```

But the current reference implementation translates it to (ignoring delegate caching and extension method expansion):

```csharp
customers.Where(c => c.City == "London").Select(c => c)
```

-> The `Select` call is not omitted

Only for queries like:

```csharp
from c in customers
where c.City == "London"
select c
```
the `Select` call is omitted.

Is this a spec or roslyn bug?

---
To make it work, compilers would need to analyze invocation expressions and "expand" the original Linq query first - which is not done in roslyn.