Merge pull request #14551 from dotnet/merges/main-to-release/dev17.5

Merge main to release/dev17.5

Author: dotnet-bot

src/Compiler/Checking/AugmentWithHashCompare.fs

@@ -996,7 +996,16 @@ let MakeBindingsForEqualityWithComparerAugmentation (g: TcGlobals) (tycon: Tycon
             // build the hash rhs
             let withcGetHashCodeExpr =
                 let compv, compe = mkCompGenLocal m "comp" g.IEqualityComparer_ty
-                let thisv, hashe = hashf g tcref tycon compe
+
+                // Special case List<T> type to avoid StackOverflow exception , call custom hash code instead
+                let thisv,hashe = 
+                    if tyconRefEq g tcref g.list_tcr_canon && tycon.HasMember g "CustomHashCode" [g.IEqualityComparer_ty] then
+                        let customCodeVal = (tycon.TryGetMember g "CustomHashCode" [g.IEqualityComparer_ty]).Value                  
+                        let tinst, ty = mkMinimalTy g tcref
+                        let thisv, thise = mkThisVar g m ty   
+                        thisv,mkApps g ((exprForValRef m customCodeVal, customCodeVal.Type), (if isNil tinst then [] else [tinst]), [thise; compe], m)
+                    else                     
+                        hashf g tcref tycon compe
                 mkLambdas g m tps [thisv; compv] (hashe, g.int_ty)
 
             // build the equals rhs

src/Compiler/TypedTree/TypedTreeOps.fs

@@ -9573,11 +9573,11 @@ type Entity with
                 List.lengthsEqAndForall2 (typeEquiv g) (List.map fst argInfos) argTys &&  
                 membInfo.MemberFlags.IsOverrideOrExplicitImpl
             | _ -> false) 
-    
-    member tycon.HasMember g nm argTys = 
+
+    member tycon.TryGetMember g nm argTys = 
         tycon.TypeContents.tcaug_adhoc 
         |> NameMultiMap.find nm
-        |> List.exists (fun vref -> 
+        |> List.tryFind (fun vref -> 
             match vref.MemberInfo with 
             | None -> false 
             | _ ->
@@ -9586,7 +9586,8 @@ type Entity with
             match argInfos with
             | [argInfos] -> List.lengthsEqAndForall2 (typeEquiv g) (List.map fst argInfos) argTys
             | _ -> false) 
-
+    
+    member tycon.HasMember g nm argTys = (tycon.TryGetMember g nm argTys).IsSome
 
 type EntityRef with 
     member tcref.HasInterface g ty = tcref.Deref.HasInterface g ty

src/Compiler/TypedTree/TypedTreeOps.fsi

@@ -2449,6 +2449,8 @@ type Entity with
 
     member HasMember: TcGlobals -> string -> TType list -> bool
 
+    member internal TryGetMember: TcGlobals -> string -> TType list -> ValRef option
+
 type EntityRef with
 
     member HasInterface: TcGlobals -> TType -> bool

src/FSharp.Core/prim-types.fs

@@ -3912,6 +3912,16 @@ namespace Microsoft.FSharp.Collections
     type List<'T> = 
        | ([])  :                  'T list
        | ( :: )  : Head: 'T * Tail: 'T list -> 'T list
+       member private this.CustomHashCode(c:IEqualityComparer) =        
+            let rec loop l acc position =
+                match l with
+                | [] -> acc           
+                | h::t ->
+                    let hashOfH = GenericHashWithComparer c h
+                    let acc = LanguagePrimitives.HashCompare.HashCombine position acc hashOfH
+                    loop t acc (position+1)
+
+            loop this 0 0
        interface IEnumerable<'T>
        interface IEnumerable
        interface IReadOnlyCollection<'T>

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ListType.fs

@@ -120,6 +120,29 @@ type ListType() =
         Assert.AreEqual("[1; 2; 3]", [1; 2; 3].ToString())
         Assert.AreEqual("[]", [].ToString())
         Assert.AreEqual("[]", ([] : decimal list list).ToString())
+
+    [<Fact>]
+    member this.HashCodeNotThrowingStackOverflow() = 
+        let l = 1 :: 2 :: [0.. 35_000]
+        let hash = l.GetHashCode()
+
+        let l2 = [1;2] @ [0.. 35_000]
+        let hash2 = l.GetHashCode()
+
+        Assert.AreEqual(hash,hash2)
+
+    [<Fact>]
+    member this.HashCodeDoesNotThrowOnListOfNullStrings() = 
+        let l = ["1";"2";null;null]
+        Assert.AreEqual(l.GetHashCode(),l.GetHashCode())
+
+    [<Fact>]
+    member this.HashCodeIsDifferentForListsWithSamePrefix() = 
+        let sharedPrefix = [0..500]
+        let l1 = sharedPrefix @ [1]
+        let l2 = sharedPrefix @ [2]       
+
+        Assert.AreNotEqual(l1.GetHashCode(),l2.GetHashCode())
 
     [<Fact>]
     member this.ObjectEquals() =