Use Array.Empty (#1588)

Author: slozier

.editorconfig

@@ -93,6 +93,3 @@ dotnet_diagnostic.CA5350.severity = suggestion  # CA5350: Do Not Use Weak Crypto
 dotnet_diagnostic.CA5351.severity = suggestion  # CA5351: Do Not Use Broken Cryptographic Algorithms
 dotnet_diagnostic.CA5359.severity = suggestion  # CA5359: Do Not Disable Certificate Validation
 dotnet_diagnostic.CA5372.severity = suggestion  # CA5372: Use XmlReader For XPathDocument
-
-# TODO: remove this
-dotnet_diagnostic.CA1825.severity = suggestion  # CA1825: Avoid zero-length array allocations

Src/IronPython.Modules/_ctypes/StructType.cs

@@ -32,7 +32,7 @@ public static partial class CTypes {
         public class StructType : PythonType, INativeType {
             internal Field[] _fields;
             private int? _size, _alignment, _pack;
-            private static readonly Field[] _emptyFields = new Field[0]; // fields were never initialized before a type was created
+            private static readonly Field[] _emptyFields = System.Array.Empty<Field>(); // fields were never initialized before a type was created
 
             public StructType(CodeContext/*!*/ context, string name, PythonTuple bases, PythonDictionary members)
                 : base(context, name, bases, members) {

Src/IronPython.Modules/_ctypes/_ctypes.cs

@@ -380,7 +380,7 @@ public static object call_cdeclfunction(CodeContext context, IntPtr address, Pyt
 
             _CFuncPtr func = (_CFuncPtr)funcType.CreateInstance(context, address);
 
-            return PythonOps.CallWithArgsTuple(func, new object[0], args);
+            return PythonOps.CallWithArgsTuple(func, System.Array.Empty<object>(), args);
         }
 
         public static void call_commethod() {
@@ -399,7 +399,7 @@ public static object call_function(CodeContext context, IntPtr address, PythonTu
 
             _CFuncPtr func = (_CFuncPtr)funcType.CreateInstance(context, address);
 
-            return PythonOps.CallWithArgsTuple(func, new object[0], args);
+            return PythonOps.CallWithArgsTuple(func, System.Array.Empty<object>(), args);
         }
 
         private static CFuncPtrType GetFunctionType(CodeContext context, int flags) {
@@ -513,7 +513,7 @@ private static ModuleBuilder DynamicModule {
                     lock (_lock) {
                         if (_dynamicModule == null) {
                             var attributes = new[] {
-                                new CustomAttributeBuilder(typeof(UnverifiableCodeAttribute).GetConstructor(ReflectionUtils.EmptyTypes), new object[0]),
+                                new CustomAttributeBuilder(typeof(UnverifiableCodeAttribute).GetConstructor(ReflectionUtils.EmptyTypes), System.Array.Empty<object>()),
 #if !NETCOREAPP && !NETSTANDARD
                                 //PermissionSet(SecurityAction.Demand, Unrestricted = true)
                                 new CustomAttributeBuilder(typeof(PermissionSetAttribute).GetConstructor(new Type[] { typeof(SecurityAction) }),

Src/IronPython.Modules/hashlib/_hashlib.cs

@@ -23,7 +23,7 @@ public abstract class HashBase<T> : ICloneable where T : HashAlgorithm {
         protected T _hasher;
         private static MethodInfo _memberwiseClone;
 
-        private static readonly byte[] _empty = new byte[0];
+        private static readonly byte[] _empty = Array.Empty<byte>();
 
         public readonly string name;
         public readonly int block_size;
@@ -87,7 +87,7 @@ protected T CloneHasher() {
 
             if (_memberwiseClone != null) {
                 lock (_hasher) {
-                    clone = (T)_memberwiseClone.Invoke(_hasher, new object[0]);
+                    clone = (T)_memberwiseClone.Invoke(_hasher, Array.Empty<object>());
                 }
             }
 

Src/IronPython.SQLite/Cursor.cs

@@ -354,7 +354,7 @@ private object fetchOneRow(CodeContext context)
 
                             case Sqlite3.SQLITE_BLOB:
                             default:
-                                converted = new Bytes(Sqlite3.sqlite3_column_blob(this.statement.st, i) ?? new byte[0]); // TODO: avoid creating a copy
+                                converted = new Bytes(Sqlite3.sqlite3_column_blob(this.statement.st, i) ?? Array.Empty<byte>()); // TODO: avoid creating a copy
                                 break;
                         }
                     }

Src/IronPython.SQLite/c#sqlite/vdbeaux_c.cs

@@ -1646,7 +1646,7 @@ Vdbe p                   /* The VDBE */
       int i;                               /* Loop counter */
       int rc = SQLITE_OK;                  /* Return code */
       if ( p.pResultSet == null )
-        p.pResultSet = new Mem[0];//Mem* pMem = p.pResultSet = p.aMem[1];   /* First Mem of result set */
+        p.pResultSet = Array.Empty<Mem>();//Mem* pMem = p.pResultSet = p.aMem[1];   /* First Mem of result set */
       Mem pMem;
       Debug.Assert( p.explain != 0 );
       Debug.Assert( p.magic == VDBE_MAGIC_RUN );

Src/IronPython/Compiler/Ast/Node.cs

@@ -30,7 +30,7 @@ namespace IronPython.Compiler.Ast {
 
     public abstract class Node : MSAst.Expression {
         internal static readonly BlockExpression EmptyBlock = Ast.Block(AstUtils.Empty());
-        internal static readonly MSAst.Expression[] EmptyExpression = new MSAst.Expression[0];
+        internal static readonly MSAst.Expression[] EmptyExpression = Array.Empty<Ast>();
 
         internal static ParameterExpression FunctionStackVariable = Ast.Variable(typeof(List<FunctionStack>), "$funcStack");
         internal static readonly LabelTarget GeneratorLabel = Ast.Label(typeof(object), "$generatorLabel");

Src/IronPython/Compiler/Ast/TryStatement.cs

@@ -27,7 +27,7 @@ namespace IronPython.Compiler.Ast {
     public class TryStatement : Statement {
         private readonly TryStatementHandler[] _handlers;
 
-        private static readonly TryStatementHandler[] emptyArray = new TryStatementHandler[0];
+        private static readonly TryStatementHandler[] emptyArray = Array.Empty<TryStatementHandler>();
 
         public TryStatement(Statement body, TryStatementHandler[]? handlers, Statement? else_, Statement? finally_) {
             Body = body;

Src/IronPython/Compiler/GeneratorRewriter.cs

@@ -411,7 +411,7 @@ protected override Expression VisitTry(TryExpression node) {
                 block[1] = Expression.MakeTry(null, @try, null, null, new ReadOnlyCollection<CatchBlock>(handlers));
                 @try = Expression.Block(block);
                 Debug.Assert(@try.Type == node.Body.Type);
-                handlers = new CatchBlock[0]; // so we don't reuse these
+                handlers = Array.Empty<CatchBlock>(); // so we don't reuse these
             }
 
             if (finallyYields != catchYields) {
@@ -433,7 +433,7 @@ protected override Expression VisitTry(TryExpression node) {
                 if (handlers.Count > 0) {
                     @try = Expression.MakeTry(null, @try, null, null, handlers);
                     Debug.Assert(@try.Type == node.Body.Type);
-                    handlers = new CatchBlock[0];
+                    handlers = Array.Empty<CatchBlock>();
                 }
 
                 // NOTE: the order of these routers is important

Src/IronPython/Modules/_ast.cs

@@ -68,7 +68,7 @@ internal static PythonAst ConvertToPythonAst(CodeContext codeContext, AST source
             } else
                 throw PythonOps.TypeError("unsupported type of AST: {0}", (source.GetType()));
 
-            return new PythonAst(stmt, false, ModuleOptions.ExecOrEvalCode, printExpression, compilerContext, new int[] { });
+            return new PythonAst(stmt, false, ModuleOptions.ExecOrEvalCode, printExpression, compilerContext, Array.Empty<int>());
         }
 
         internal static AST BuildAst(CodeContext context, SourceUnit sourceUnit, PythonCompilerOptions opts, string mode) {