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Merged
Ilya (iSazonov) merged 7 commits into from
Nov 4, 2020
Merged

Enable CA1825: Avoid zero-length array allocations #13961

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Enable CA1825: Avoid zero-length array allocations
xtqqczze Nov 1, 2020
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Remove outdated comments
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Remove outdated content
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Revert changes and suppress rule
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2 changes: 1 addition & 1 deletion .globalconfig
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Expand Up @@ -286,7 +286,7 @@ dotnet_diagnostic.CA1823.severity = none
dotnet_diagnostic.CA1824.severity = suggestion

# CA1825: Avoid zero-length array allocations
dotnet_diagnostic.CA1825.severity = suggestion
dotnet_diagnostic.CA1825.severity = warning

# CA1826: Do not use Enumerable methods on indexable collections
dotnet_diagnostic.CA1826.severity = suggestion
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3 changes: 0 additions & 3 deletions docs/dev-process/coding-guidelines.md
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Expand Up @@ -111,9 +111,6 @@ Some general guidelines:
* Avoid using string interpolations and overloads with implicit parameters such as `Culture` and `StringComparison`.
Instead, use overloads with more explicit parameters such as `String.Format(IFormatProvider, String, Object[])` and `Equals(String, String, StringComparison)`.

* Avoid creating empty arrays.
Comment thread
xtqqczze marked this conversation as resolved.
Instead, reuse the static ones via `Utils.EmptyArray<T>`.

* Avoid unnecessary memory allocation in a loop.
Move the memory allocation outside the loop if possible.

Expand Down
2 changes: 1 addition & 1 deletion src/Microsoft.PowerShell.Commands.Utility/commands/utility/ImplicitRemotingCommands.cs
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Expand Up @@ -480,7 +480,7 @@ public ModuleSpecification[] FullyQualifiedModule
}
}

private ModuleSpecification[] _moduleSpecifications = new ModuleSpecification[0];
private ModuleSpecification[] _moduleSpecifications = Array.Empty<ModuleSpecification>();
internal bool IsFullyQualifiedModuleSpecified = false;

private bool _commandParameterSpecified; // initialized to default value in the constructor
Expand Down
8 changes: 4 additions & 4 deletions src/Microsoft.PowerShell.Commands.Utility/commands/utility/MatchString.cs
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Expand Up @@ -366,7 +366,7 @@ private string FormatLine(string lineStr, int displayLineNumber, string displayP
/// <summary>
/// Gets or sets a list of all Regex matches on the matching line.
/// </summary>
public Match[] Matches { get; set; } = new Match[] { };
public Match[] Matches { get; set; } = Array.Empty<Match>();

/// <summary>
/// Create a deep copy of this MatchInfo instance.
Expand Down Expand Up @@ -1897,8 +1897,8 @@ private bool DoMatchWorker(string operandString, MatchInfo matchInfo, out MatchI
if (matchInfo.Context != null)
{
matchResult = matchInfo.Clone();
matchResult.Context.DisplayPreContext = new string[] { };
matchResult.Context.DisplayPostContext = new string[] { };
matchResult.Context.DisplayPreContext = Array.Empty<string>();
matchResult.Context.DisplayPostContext = Array.Empty<string>();
}
else
{
Expand All @@ -1924,7 +1924,7 @@ private bool DoMatchWorker(string operandString, MatchInfo matchInfo, out MatchI

// Matches should be an empty list, rather than null,
// in the cases of notMatch and simpleMatch.
matchResult.Matches = matches ?? new Match[] { };
matchResult.Matches = matches ?? Array.Empty<Match>();

return true;
}
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2 changes: 1 addition & 1 deletion src/Microsoft.PowerShell.Commands.Utility/commands/utility/New-Object.cs
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Expand Up @@ -207,7 +207,7 @@ protected override void BeginProcessing()
ConstructorInfo ci = type.GetConstructor(Type.EmptyTypes);
if (ci != null && ci.IsPublic)
{
_newObject = CallConstructor(type, new ConstructorInfo[] { ci }, new object[] { });
_newObject = CallConstructor(type, new ConstructorInfo[] { ci }, Array.Empty<object>());
if (_newObject != null && Property != null)
{
// The method invocation is disabled for "Hashtable to Object conversion" (Win8:649519), but we need to keep it enabled for New-Object for compatibility to PSv2
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2 changes: 1 addition & 1 deletion src/System.Management.Automation/engine/EventManager.cs
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Expand Up @@ -599,7 +599,7 @@ private void OnElapsedEvent(object source)
if (_engineEventSubscribers.TryGetValue(PSEngineEvent.OnIdle, out subscribers) && subscribers.Count > 0)
{
// We send out on-idle event and keep enabling the timer only if there still are subscribers to the on-idle event
GenerateEvent(PSEngineEvent.OnIdle, null, new object[] { }, null, false, false);
GenerateEvent(PSEngineEvent.OnIdle, null, Array.Empty<object>(), null, false, false);
EnableTimer();
}
else
Expand Down
2 changes: 1 addition & 1 deletion src/System.Management.Automation/engine/LanguagePrimitives.cs
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Expand Up @@ -384,7 +384,7 @@ private void CreateGetEnumerator()

emitter.Emit(OpCodes.Ldarg_0);
emitter.Emit(OpCodes.Castclass, _enumerableType);
MethodInfo methodInfo = _enumerableType.GetMethod("GetEnumerator", new Type[] { });
MethodInfo methodInfo = _enumerableType.GetMethod("GetEnumerator", Array.Empty<Type>());
emitter.Emit(OpCodes.Callvirt, methodInfo);
emitter.Emit(OpCodes.Ret);
}
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2 changes: 1 addition & 1 deletion src/System.Management.Automation/engine/Modules/ModuleCmdletBase.cs
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Expand Up @@ -6882,7 +6882,7 @@ internal PSModuleInfo LoadBinaryModule(PSModuleInfo parentModule, bool trySnapIn
iss.Bind(Context, updateOnly: true, module, options.NoClobber, options.Local, setLocation: false);

// Scan all of the types in the assembly to register JobSourceAdapters.
IEnumerable<Type> allTypes = new Type[] { };
IEnumerable<Type> allTypes = Array.Empty<Type>();
if (assembly != null)
{
allTypes = assembly.ExportedTypes;
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2 changes: 1 addition & 1 deletion src/System.Management.Automation/engine/ParameterBinderBase.cs
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Expand Up @@ -1559,7 +1559,7 @@ private object EncodeCollection(
toType,
0,
null,
new object[] { },
Array.Empty<object>(),
System.Globalization.CultureInfo.InvariantCulture);
if (collectionTypeInformation.ParameterCollectionType == ParameterCollectionType.IList)
resultAsIList = (IList)resultCollection;
Expand Down
2 changes: 1 addition & 1 deletion src/System.Management.Automation/engine/PseudoParameters.cs
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Expand Up @@ -236,6 +236,6 @@ public string HelpFile
/// </summary>
public object Data { get; set; }

internal static readonly RuntimeDefinedParameter[] EmptyParameterArray = new RuntimeDefinedParameter[0];
internal static readonly RuntimeDefinedParameter[] EmptyParameterArray = Array.Empty<RuntimeDefinedParameter>();

@xtqqczze xtqqczze Nov 1, 2020

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Perhaps we can inline EmptyParameterArray ?

@iSazonov Ilya (iSazonov) Nov 2, 2020

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Not in the PR.

}
}
2 changes: 1 addition & 1 deletion src/System.Management.Automation/engine/hostifaces/LocalConnection.cs
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Expand Up @@ -851,7 +851,7 @@ private void DoCloseHelper()

// Generate the shutdown event
if (Events != null)
Events.GenerateEvent(PSEngineEvent.Exiting, null, new object[] { }, null, true, false);
Events.GenerateEvent(PSEngineEvent.Exiting, null, Array.Empty<object>(), null, true, false);

// Stop all running pipelines
// Note:Do not perform the Cancel in lock. Reason is
Expand Down
54 changes: 27 additions & 27 deletions src/System.Management.Automation/engine/remoting/host/RemoteHostMethodInfo.cs
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Expand Up @@ -144,35 +144,35 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHost),
"get_Name",
typeof(string),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetVersion:
return new RemoteHostMethodInfo(
typeof(PSHost),
"get_Version",
typeof(Version),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetInstanceId:
return new RemoteHostMethodInfo(
typeof(PSHost),
"get_InstanceId",
typeof(Guid),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetCurrentCulture:
return new RemoteHostMethodInfo(
typeof(PSHost),
"get_CurrentCulture",
typeof(System.Globalization.CultureInfo),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetCurrentUICulture:
return new RemoteHostMethodInfo(
typeof(PSHost),
"get_CurrentUICulture",
typeof(System.Globalization.CultureInfo),
new Type[] { });
Array.Empty<Type>());

// Host methods.

Expand All @@ -188,28 +188,28 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHost),
"EnterNestedPrompt",
typeof(void),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.ExitNestedPrompt:
return new RemoteHostMethodInfo(
typeof(PSHost),
"ExitNestedPrompt",
typeof(void),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.NotifyBeginApplication:
return new RemoteHostMethodInfo(
typeof(PSHost),
"NotifyBeginApplication",
typeof(void),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.NotifyEndApplication:
return new RemoteHostMethodInfo(
typeof(PSHost),
"NotifyEndApplication",
typeof(void),
new Type[] { });
Array.Empty<Type>());

// Host UI methods.

Expand All @@ -218,14 +218,14 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostUserInterface),
"ReadLine",
typeof(string),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.ReadLineAsSecureString:
return new RemoteHostMethodInfo(
typeof(PSHostUserInterface),
"ReadLineAsSecureString",
typeof(System.Security.SecureString),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.Write1:
return new RemoteHostMethodInfo(
Expand All @@ -246,7 +246,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostUserInterface),
"WriteLine",
typeof(void),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.WriteLine2:
return new RemoteHostMethodInfo(
Expand Down Expand Up @@ -339,7 +339,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_ForegroundColor",
typeof(ConsoleColor),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetForegroundColor:
return new RemoteHostMethodInfo(
Expand All @@ -353,7 +353,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_BackgroundColor",
typeof(ConsoleColor),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetBackgroundColor:
return new RemoteHostMethodInfo(
Expand All @@ -367,7 +367,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_CursorPosition",
typeof(Coordinates),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetCursorPosition:
return new RemoteHostMethodInfo(
Expand All @@ -381,7 +381,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_WindowPosition",
typeof(Coordinates),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetWindowPosition:
return new RemoteHostMethodInfo(
Expand All @@ -395,7 +395,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_CursorSize",
typeof(int),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetCursorSize:
return new RemoteHostMethodInfo(
Expand All @@ -409,7 +409,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_BufferSize",
typeof(Size),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetBufferSize:
return new RemoteHostMethodInfo(
Expand All @@ -423,7 +423,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_WindowSize",
typeof(Size),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetWindowSize:
return new RemoteHostMethodInfo(
Expand All @@ -437,7 +437,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_WindowTitle",
typeof(string),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetWindowTitle:
return new RemoteHostMethodInfo(
Expand All @@ -453,21 +453,21 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"get_MaxWindowSize",
typeof(Size),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetMaxPhysicalWindowSize:
return new RemoteHostMethodInfo(
typeof(PSHostRawUserInterface),
"get_MaxPhysicalWindowSize",
typeof(Size),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetKeyAvailable:
return new RemoteHostMethodInfo(
typeof(PSHostRawUserInterface),
"get_KeyAvailable",
typeof(bool),
new Type[] { });
Array.Empty<Type>());

// Host raw UI methods.

Expand All @@ -483,7 +483,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(PSHostRawUserInterface),
"FlushInputBuffer",
typeof(void),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.SetBufferContents1:
return new RemoteHostMethodInfo(
Expand Down Expand Up @@ -527,7 +527,7 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(IHostSupportsInteractiveSession),
"PopRunspace",
typeof(void),
new Type[] { });
Array.Empty<Type>());

// IHostSupportsInteractiveSession properties.

Expand All @@ -536,14 +536,14 @@ internal static RemoteHostMethodInfo LookUp(RemoteHostMethodId methodId)
typeof(IHostSupportsInteractiveSession),
"get_IsRunspacePushed",
typeof(bool),
new Type[] { });
Array.Empty<Type>());

case RemoteHostMethodId.GetRunspace:
return new RemoteHostMethodInfo(
typeof(IHostSupportsInteractiveSession),
"get_Runspace",
typeof(System.Management.Automation.Runspaces.Runspace),
new Type[] { });
Array.Empty<Type>());

default:
Dbg.Assert(false, "All RemoteHostMethodId's should be handled. This code should not be reached.");
Expand Down
5 changes: 4 additions & 1 deletion src/System.Management.Automation/engine/runtime/Operations/ArrayOps.cs
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Expand Up @@ -52,7 +52,10 @@ internal static T[] Multiply<T>(T[] array, uint times)

if (times == 0 || array.Length == 0)
{
return new T[0]; // don't use Utils.EmptyArray, always return a new array
#pragma warning disable CA1825 // Avoid zero-length array allocations
// Don't use Array.Empty<T>(); always return a new instance.
return new T[0];
#pragma warning restore CA1825 // Avoid zero-length array allocations
}

var context = LocalPipeline.GetExecutionContextFromTLS();
Expand Down
5 changes: 4 additions & 1 deletion src/System.Management.Automation/engine/runtime/Operations/MiscOps.cs
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Expand Up @@ -3228,7 +3228,10 @@ internal static object Multiply(IEnumerator enumerator, uint times)

if (originalList.Count == 0)
{
return new object[0]; // don't use Utils.EmptyArray, always return a new array
#pragma warning disable CA1825 // Avoid zero-length array allocations
// Don't use Array.Empty<object>(); always return a new instance.
return new object[0];
#pragma warning restore CA1825 // Avoid zero-length array allocations
}

return ArrayOps.Multiply(originalList.ToArray(), times);
Expand Down
4 changes: 2 additions & 2 deletions src/System.Management.Automation/namespaces/RegistryProvider.cs
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Expand Up @@ -3814,7 +3814,7 @@ private static object ConvertValueToKind(object value, RegistryValueKind kind)
value,
typeof(byte[]),
CultureInfo.CurrentCulture)
: new byte[] { };
: Array.Empty<byte>();
break;

case RegistryValueKind.DWord:
Expand Down Expand Up @@ -3851,7 +3851,7 @@ private static object ConvertValueToKind(object value, RegistryValueKind kind)
value,
typeof(string[]),
CultureInfo.CurrentCulture)
: new string[] { };
: Array.Empty<string>();
break;

case RegistryValueKind.QWord:
Expand Down
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