From 9dd2d5e3bb31a6517f9b826e7ca886646d52a456 Mon Sep 17 00:00:00 2001
From: Atif Aziz <code@raboof.com>
Date: Fri, 20 Nov 2020 09:35:58 +0100
Subject: [PATCH] Update to .NET 5.0 SDK (#766)

---
 .travis.yml              |  6 +++++-
 MoreLinq/MoreLinq.csproj |  4 ++--
 MoreLinq/Permutations.cs | 19 +++++++++----------
 global.json              |  2 +-
 4 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 9c82769aa..ae20362cb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,7 +8,7 @@ solution: MoreLinq.sln
 mono: 5.0.1
 dist: xenial
 sudo: required
-dotnet: 3.1.300
+dotnet: 5.0.100
 env:
   - CONFIGURATION=Debug
   - CONFIGURATION=Release
@@ -19,6 +19,7 @@ addons:
       key_url: 'https://packages.microsoft.com/keys/microsoft.asc'
     packages:
     - dotnet-runtime-2.1
+    - dotnet-runtime-3.1
 
 before_install:
   - |
@@ -28,6 +29,9 @@ before_install:
       # Install dotnet core 2.1 runtime
       wget --retry-connrefused --waitretry=1 -O /tmp/dn21.pkg 'https://download.visualstudio.microsoft.com/download/pr/9314da31-774c-4d2b-8743-998f2a21f5ab/bc918ca05ab6b650f2991b205c04f623/dotnet-runtime-2.1.13-osx-x64.pkg'
       sudo installer -pkg /tmp/dn21.pkg -target /
+      # Install dotnet core 3.1 runtime
+      wget --retry-connrefused --waitretry=1 -O /tmp/dn31.pkg 'https://download.visualstudio.microsoft.com/download/pr/cf89f4c1-b56a-4250-a927-461f17a828ac/3522d5d7cf26727e416d781533d07b65/dotnet-runtime-3.1.10-osx-x64.pkg'
+      sudo installer -pkg /tmp/dn31.pkg -target /
     fi
   - dotnet --info
 
diff --git a/MoreLinq/MoreLinq.csproj b/MoreLinq/MoreLinq.csproj
index ee4dfcdba..d61da8e75 100644
--- a/MoreLinq/MoreLinq.csproj
+++ b/MoreLinq/MoreLinq.csproj
@@ -120,7 +120,7 @@
     <VersionPrefix>3.3.2</VersionPrefix>
     <Authors>MoreLINQ Developers.</Authors>
     <TargetFrameworks>net451;netstandard1.0;netstandard2.0</TargetFrameworks>
-    <LangVersion>8</LangVersion>
+    <LangVersion>9</LangVersion>
     <Nullable>enable</Nullable>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
     <DebugType>portable</DebugType>
@@ -247,7 +247,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Nullable" Version="1.1.1">
+    <PackageReference Include="Nullable" Version="1.3.0">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>
diff --git a/MoreLinq/Permutations.cs b/MoreLinq/Permutations.cs
index 3c96161fd..0fac1001b 100644
--- a/MoreLinq/Permutations.cs
+++ b/MoreLinq/Permutations.cs
@@ -20,6 +20,7 @@ namespace MoreLinq
     using System;
     using System.Collections;
     using System.Collections.Generic;
+    using System.Diagnostics.CodeAnalysis;
     using System.Linq;
 
     public static partial class MoreEnumerable
@@ -83,25 +84,23 @@ public PermutationEnumerator(IEnumerable<T> valueSet)
                 // 1) for empty sets and sets of cardinality 1, there exists only a single permutation.
                 // 2) for sets larger than 1 element, the number of nested loops needed is: set.Count-1
                 _generator = NestedLoops(NextPermutation, Enumerable.Range(2, Math.Max(0, _valueSet.Count - 1)));
-                Reset(ref _current, ref _generatorIterator, ref _hasMoreResults);
+                Reset();
             }
 
-            public void Reset() =>
-                Reset(ref _current, ref _generatorIterator, ref _hasMoreResults);
-
-            void Reset(ref IList<T>? current, ref IEnumerator<Action> generatorIterator, ref bool hasMoreResults)
+            [MemberNotNull(nameof(_generatorIterator))]
+            public void Reset()
             {
-                current = null;
-                generatorIterator?.Dispose();
+                _current = null;
+                _generatorIterator?.Dispose();
                 // restore lexographic ordering of the permutation indexes
                 for (var i = 0; i < _permutation.Length; i++)
                     _permutation[i] = i;
                 // start a newiteration over the nested loop generator
-                generatorIterator = _generator.GetEnumerator();
+                _generatorIterator = _generator.GetEnumerator();
                 // we must advance the nestedloop iterator to the initial element,
                 // this ensures that we only ever produce N!-1 calls to NextPermutation()
-                generatorIterator.MoveNext();
-                hasMoreResults = true; // there's always at least one permutation: the original set itself
+                _generatorIterator.MoveNext();
+                _hasMoreResults = true; // there's always at least one permutation: the original set itself
             }
 
             public IList<T> Current => _current!;
diff --git a/global.json b/global.json
index aca3f3cb6..a46dc9b06 100644
--- a/global.json
+++ b/global.json
@@ -1,6 +1,6 @@
 {
   "sdk": {
-    "version": "3.1.300",
+    "version": "5.0.100",
     "rollForward": "latestFeature"
   }
 }