Enable IDE0030: UseCoalesceExpressionForNullable (#14289)

.globalconfig

@@ -1204,7 +1204,7 @@ dotnet_diagnostic.IDE0029.severity = silent
 
 # IDE0030: UseCoalesceExpressionForNullable
 # https://docs.microsoft.com/dotnet/fundamentals/code-analysis/style-rules/ide0030
-dotnet_diagnostic.IDE0030.severity = silent
+dotnet_diagnostic.IDE0030.severity = warning
 
 # IDE0031: UseNullPropagation
 # https://docs.microsoft.com/dotnet/fundamentals/code-analysis/style-rules/ide0031

src/System.Management.Automation/engine/Modules/NewModuleManifestCommand.cs

@@ -160,7 +160,7 @@ namespace Microsoft.PowerShell.Commands
         [Parameter]
         public ProcessorArchitecture ProcessorArchitecture
         {
-            get { return _processorArchitecture.HasValue ? _processorArchitecture.Value : ProcessorArchitecture.None; }
+            get { return _processorArchitecture ?? ProcessorArchitecture.None; }
 
             set { _processorArchitecture = value; }
         }

src/System.Management.Automation/engine/hostifaces/PowerShell.cs

@@ -3521,9 +3521,7 @@ namespace System.Management.Automation
                 ActionPreference preference;
                 if (_batchInvocationSettings != null)
                 {
-                    preference = (_batchInvocationSettings.ErrorActionPreference.HasValue) ?
-                        _batchInvocationSettings.ErrorActionPreference.Value
-                        : ActionPreference.Continue;
+                    preference = _batchInvocationSettings.ErrorActionPreference ?? ActionPreference.Continue;
                 }
                 else
                 {

src/System.Management.Automation/engine/remoting/commands/NewPSSessionOptionCommand.cs

@@ -136,8 +136,7 @@ namespace Microsoft.PowerShell.Commands
         {
             get
             {
-                return _openTimeout.HasValue ? _openTimeout.Value :
-                    RunspaceConnectionInfo.DefaultOpenTimeout;
+                return _openTimeout ?? RunspaceConnectionInfo.DefaultOpenTimeout;
             }
 
             set
@@ -164,8 +163,7 @@ namespace Microsoft.PowerShell.Commands
         {
             get
             {
-                return _cancelTimeout.HasValue ? _cancelTimeout.Value :
-                    BaseTransportManager.ClientCloseTimeoutMs;
+                return _cancelTimeout ?? BaseTransportManager.ClientCloseTimeoutMs;
             }
 
             set
@@ -189,8 +187,7 @@ namespace Microsoft.PowerShell.Commands
         {
             get
             {
-                return _idleTimeout.HasValue ? _idleTimeout.Value
-                    : RunspaceConnectionInfo.DefaultIdleTimeout;
+                return _idleTimeout ?? RunspaceConnectionInfo.DefaultIdleTimeout;
             }
 
             set
@@ -299,8 +296,7 @@ namespace Microsoft.PowerShell.Commands
         {
             get
             {
-                return (_operationtimeout.HasValue ? _operationtimeout.Value :
-                    BaseTransportManager.ClientDefaultOperationTimeoutMs);
+                return _operationtimeout ?? BaseTransportManager.ClientDefaultOperationTimeoutMs;
             }
 
             set

src/System.Management.Automation/engine/remoting/server/ServerRunspacePoolDriver.cs

@@ -168,7 +168,7 @@ namespace System.Management.Automation
             // The default server settings is to make new commands execute in the calling thread...this saves
             // thread switching time and thread pool pressure on the service.
             // Users can override the server settings only if they are administrators
-            PSThreadOptions serverThreadOptions = configData.ShellThreadOptions.HasValue ? configData.ShellThreadOptions.Value : PSThreadOptions.UseCurrentThread;
+            PSThreadOptions serverThreadOptions = configData.ShellThreadOptions ?? PSThreadOptions.UseCurrentThread;
             if (threadOptions == PSThreadOptions.Default || threadOptions == serverThreadOptions)
             {
                 RunspacePool.ThreadOptions = serverThreadOptions;
@@ -184,7 +184,7 @@ namespace System.Management.Automation
             }
 
             // Set Thread ApartmentState for this RunspacePool
-            ApartmentState serverApartmentState = configData.ShellThreadApartmentState.HasValue ? configData.ShellThreadApartmentState.Value : Runspace.DefaultApartmentState;
+            ApartmentState serverApartmentState = configData.ShellThreadApartmentState ?? Runspace.DefaultApartmentState;
 
             if (apartmentState == ApartmentState.Unknown || apartmentState == serverApartmentState)
             {