Reenable compound assignment preference (PowerShell#17784)

Author: Molkree

.editorconfig

@@ -114,7 +114,6 @@ dotnet_style_prefer_conditional_expression_over_return = true:silent
 dotnet_style_prefer_conditional_expression_over_assignment = true:silent
 dotnet_style_prefer_auto_properties = true:suggestion
 csharp_prefer_simple_default_expression = true:suggestion
-dotnet_style_prefer_compound_assignment = false:silent
 dotnet_diagnostic.IDE0031.severity = none
 
 dotnet_code_quality_unused_parameters = non_public:suggestion

src/System.Management.Automation/singleshell/config/MshSnapinInfo.cs

@@ -1284,7 +1284,9 @@ private static IList<DefaultPSSnapInInformation> DefaultMshSnapins
                 {
                     lock (s_syncObject)
                     {
+#pragma warning disable IDE0074 // Disabling the rule because it can't be applied on non Unix
                         if (s_defaultMshSnapins == null)
+#pragma warning restore IDE0074
                         {
                             s_defaultMshSnapins = new List<DefaultPSSnapInInformation>()
                             {

src/System.Management.Automation/utils/tracing/PSSysLogProvider.cs

@@ -49,11 +49,8 @@ private static StringBuilder PayloadBuilder
         {
             get
             {
-                if (t_payloadBuilder == null)
-                {
-                    // NOTE: Thread static fields must be explicitly initialized for each thread.
-                    t_payloadBuilder = new StringBuilder(200);
-                }
+                // NOTE: Thread static fields must be explicitly initialized for each thread.
+                t_payloadBuilder ??= new StringBuilder(200);
 
                 return t_payloadBuilder;
             }

src/System.Management.Automation/utils/tracing/SysLogProvider.cs

@@ -130,11 +130,8 @@ private static StringBuilder MessageBuilder
         {
             get
             {
-                if (t_messageBuilder == null)
-                {
-                    // NOTE: Thread static fields must be explicitly initialized for each thread.
-                    t_messageBuilder = new StringBuilder(200);
-                }
+                // NOTE: Thread static fields must be explicitly initialized for each thread.
+                t_messageBuilder ??= new StringBuilder(200);
 
                 return t_messageBuilder;
             }
@@ -201,10 +198,7 @@ private bool ShouldLog(PSLevel level, PSKeyword keywords, PSChannel channel)
         {
             get
             {
-                if (_resourceManager is null)
-                {
-                    _resourceManager = new global::System.Resources.ResourceManager("System.Management.Automation.resources.EventResource", typeof(EventResource).Assembly);
-                }
+                _resourceManager ??= new global::System.Resources.ResourceManager("System.Management.Automation.resources.EventResource", typeof(EventResource).Assembly);
 
                 return _resourceManager;
             }

test/tools/WebListener/Controllers/RetryController.cs

@@ -23,10 +23,7 @@ public class RetryController : Controller
 
         public JsonResult Retry(string sessionId, int failureCode, int failureCount)
         {
-            if (retryInfo == null)
-            {
-                retryInfo = new Dictionary<string, Tuple<int, int, int>>();
-            }
+            retryInfo ??= new Dictionary<string, Tuple<int, int, int>>();
 
             if (retryInfo.TryGetValue(sessionId, out Tuple<int, int, int> retry))
             {