Bug 16530 - Bug in LINQ Join over IEnumerable data when both rows have a "null" key
Summary: Bug in LINQ Join over IEnumerable data when both rows have a "null" key
Alias: None
Product: Class Libraries
Classification: Mono
Component: System.Core ()
Version: 3.2.x
Hardware: PC All
: --- normal
Target Milestone: Untriaged
Assignee: Marek Safar
Depends on:
Reported: 2013-11-30 10:55 UTC by donsyme
Modified: 2013-12-02 13:07 UTC (History)
2 users (show)

Is this bug a regression?: ---
Last known good build:

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Description donsyme 2013-11-30 10:55:12 UTC
This is a bug in the Mono Join method implementation for IEnumerables when used with Nullables. Joins are happening for rows where both columns have "null", this is a mistake. This is still present in 3.2.5.

F# repro below (there will be a C# repro too). .NET gives the right results.

GroupJoin should also be checked.


open System
open System.Linq

type Customer(name:string, cost:float, quantity:Nullable<int>) = 
    member x.Name = name
    member x.Cost = cost
    member x.Quantity = quantity

let c1 = Customer( name="Don", cost=6.2, quantity=Nullable())
let c2 = Customer( name="Peter", cost=4.2, quantity=Nullable(10))

let db = [c1;c2]

db.Join(db,(fun i -> i.Quantity),(fun i -> i.Quantity),(fun i j -> (i.Cost, j.Cost))).ToArray()
// expect [(4.2, 4.2)]
// get  [(6.2, 6.2); (4.2, 4.2)]
Comment 1 Marek Safar 2013-12-02 13:07:53 UTC
Fixed in master