fix(array): make the Array.length null exception containing the param… (#10337)

Author: natalie-o-perret

src/fsharp/FSharp.Core/array.fs

@@ -23,7 +23,9 @@ namespace Microsoft.FSharp.Collections
         let inline indexNotFound() = raise (KeyNotFoundException(SR.GetString(SR.keyNotFoundAlt)))
 
         [<CompiledName("Length")>]
-        let length (array: _[])    = array.Length
+        let length (array: _[])    = 
+            checkNonNull "array" array
+            array.Length
 
         [<CompiledName("Last")>]
         let inline last (array: 'T[]) =

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule2.fs

@@ -44,8 +44,14 @@ type ArrayModule2() =
 
         // null array
         let nullArr = null:string[]      
-        CheckThrowsNullRefException (fun () -> Array.length  nullArr  |> ignore)  
+        CheckThrowsArgumentNullException (fun () -> Array.length  nullArr  |> ignore)  
 
+        // null array, argument name showing up
+        try
+            Array.length nullArr |> ignore
+        with 
+        | :? ArgumentNullException as e -> Assert.Equal("array", e.ParamName) |> ignore
+
         ()
 
     [<Fact>]

tests/fsharpqa/Source/Optimizations/ForLoop/ZeroToArrLength02.il.bsl

@@ -1,9 +1,6 @@
 
-//  Microsoft (R) .NET Framework IL Disassembler.  Version 4.6.1055.0
+//  Microsoft (R) .NET Framework IL Disassembler.  Version 4.8.3928.0
 //  Copyright (c) Microsoft Corporation.  All rights reserved.
-
-
-
 // Metadata version: v4.0.30319
 .assembly extern mscorlib
 {
@@ -13,82 +10,78 @@
 .assembly extern FSharp.Core
 {
   .publickeytoken = (B0 3F 5F 7F 11 D5 0A 3A )                         // .?_....:
-  .ver 4:4:1:0
+  .ver 5:0:0:0
 }
 .assembly ZeroToArrLength02
 {
   .custom instance void [FSharp.Core]Microsoft.FSharp.Core.FSharpInterfaceDataVersionAttribute::.ctor(int32,
                                                                                                       int32,
                                                                                                       int32) = ( 01 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 ) 
-
   // --- The following custom attribute is added automatically, do not uncomment -------
   //  .custom instance void [mscorlib]System.Diagnostics.DebuggableAttribute::.ctor(valuetype [mscorlib]System.Diagnostics.DebuggableAttribute/DebuggingModes) = ( 01 00 01 00 00 00 00 00 ) 
-
   .hash algorithm 0x00008004
   .ver 0:0:0:0
 }
 .mresource public FSharpSignatureData.ZeroToArrLength02
 {
-  // Offset: 0x00000000 Length: 0x000001E0
+  // Offset: 0x00000000 Length: 0x0000020E
 }
 .mresource public FSharpOptimizationData.ZeroToArrLength02
 {
-  // Offset: 0x000001E8 Length: 0x0000007B
+  // Offset: 0x00000218 Length: 0x0000007B
 }
 .module ZeroToArrLength02.dll
-// MVID: {59B18AEE-A36B-03A7-A745-0383EE8AB159}
+// MVID: {5F9557F9-A36B-03A7-A745-0383F957955F}
 .imagebase 0x00400000
 .file alignment 0x00000200
 .stackreserve 0x00100000
 .subsystem 0x0003       // WINDOWS_CUI
 .corflags 0x00000001    //  ILONLY
-// Image base: 0x01550000
-
-
+// Image base: 0x04D90000
 // =============== CLASS MEMBERS DECLARATION ===================
-
 .class public abstract auto ansi sealed ZeroToArrLength02
        extends [mscorlib]System.Object
 {
   .custom instance void [FSharp.Core]Microsoft.FSharp.Core.CompilationMappingAttribute::.ctor(valuetype [FSharp.Core]Microsoft.FSharp.Core.SourceConstructFlags) = ( 01 00 07 00 00 00 00 00 ) 
   .method public static void  f1(int32[] arr) cil managed
   {
-    // Code size       23 (0x17)
+    // Code size       34 (0x22)
     .maxstack  5
-    .locals init ([0] int32 i)
+    .locals init ([0] int32 V_0,
+             [1] int32 i)
     .language '{AB4F38C9-B6E6-43BA-BE3B-58080B2CCCE3}', '{994B45C4-E6E9-11D2-903F-00C04FA302A1}', '{5A869D0B-6611-11D3-BD2A-0000F80849BD}'
-    .line 6,6 : 5,41 'C:\\GitHub\\dsyme\\visualfsharp\\tests\\fsharpqa\\Source\\Optimizations\\ForLoop\\ZeroToArrLength02.fs'
+    .line 6,6 : 5,41 'C:\\Users\\Michelle\\Desktop\\Personal\\Repos\\fsharp\\tests\\fsharpqa\\source\\Optimizations\\ForLoop\\ZeroToArrLength02.fs'
     IL_0000:  ldc.i4.0
-    IL_0001:  stloc.0
-    IL_0002:  br.s       IL_0010
-
+    IL_0001:  stloc.1
+    IL_0002:  ldarg.0
+    IL_0003:  call       int32 [FSharp.Core]Microsoft.FSharp.Collections.ArrayModule::Length<int32>(!!0[])
+    IL_0008:  ldc.i4.1
+    IL_0009:  sub
+    IL_000a:  stloc.0
+    IL_000b:  ldloc.0
+    IL_000c:  ldloc.1
+    IL_000d:  blt.s      IL_0021
     .line 7,7 : 9,21 ''
-    IL_0004:  ldarg.0
-    IL_0005:  ldloc.0
-    IL_0006:  ldloc.0
-    IL_0007:  stelem     [mscorlib]System.Int32
-    IL_000c:  ldloc.0
-    IL_000d:  ldc.i4.1
-    IL_000e:  add
-    IL_000f:  stloc.0
+    IL_000f:  ldarg.0
+    IL_0010:  ldloc.1
+    IL_0011:  ldloc.1
+    IL_0012:  stelem     [mscorlib]System.Int32
+    IL_0017:  ldloc.1
+    IL_0018:  ldc.i4.1
+    IL_0019:  add
+    IL_001a:  stloc.1
     .line 6,6 : 5,41 ''
-    IL_0010:  ldloc.0
-    IL_0011:  ldarg.0
-    IL_0012:  ldlen
-    IL_0013:  conv.i4
-    IL_0014:  blt.s      IL_0004
-
-    IL_0016:  ret
+    IL_001b:  ldloc.1
+    IL_001c:  ldloc.0
+    IL_001d:  ldc.i4.1
+    IL_001e:  add
+    IL_001f:  bne.un.s   IL_000f
+    IL_0021:  ret
   } // end of method ZeroToArrLength02::f1
-
 } // end of class ZeroToArrLength02
-
 .class private abstract auto ansi sealed '<StartupCode$ZeroToArrLength02>'.$ZeroToArrLength02
        extends [mscorlib]System.Object
 {
 } // end of class '<StartupCode$ZeroToArrLength02>'.$ZeroToArrLength02
-
-
 // =============================================================
-
 // *********** DISASSEMBLY COMPLETE ***********************