Change GetParametersNoCopy to GetParametersAsSpan and use it in a few…

… more places (#92310)

* Change GetParametersNoCopy to GetParametersAsSpan and use it  in a few more places

The internal GetParametersNoCopy avoids a defensive ParameterInfo[] copy, but it requires the callers to promise not to mutate the array. I'm changing the method to return a `ReadOnlySpan<ParameterInfo>`, which means a caller can't mutate it without using unsafe code, and enabling the compiler to flag any misuse.  I've then used it in a few more places. We might subsequently want to consider exposing it publicly.

* Update src/libraries/Common/src/System/Runtime/InteropServices/ComEventsMethod.cs

src/coreclr/System.Private.CoreLib/src/Internal/Runtime/InteropServices/ComActivator.cs

@@ -201,7 +201,7 @@ private static void ClassRegistrationScenarioForType(ComActivationContext cxt, b
  }
 
  // Finally validate signature
- ParameterInfo[] methParams = method.GetParameters();
+ ReadOnlySpan<ParameterInfo> methParams = method.GetParametersAsSpan();
  if (method.ReturnType != typeof(void)
  || methParams == null
  || methParams.Length != 1

src/coreclr/System.Private.CoreLib/src/System/Attribute.CoreCLR.cs

@@ -227,8 +227,7 @@ private static bool InternalIsDefined(EventInfo element, Type attributeType, boo
  }
  else
  {
- ParameterInfo[] parameters = rtMethod.GetParameters();
- return parameters[position]; // Point to the correct ParameterInfo of the method
+ return rtMethod.GetParametersAsSpan()[position]; // Point to the correct ParameterInfo of the method
  }
  }
  }

src/coreclr/System.Private.CoreLib/src/System/Delegate.CoreCLR.cs

@@ -200,7 +200,7 @@ protected virtual MethodInfo GetMethodImpl()
  {
  // it's an open one, need to fetch the first arg of the instantiation
  MethodInfo invoke = this.GetType().GetMethod("Invoke")!;
- declaringType = (RuntimeType)invoke.GetParameters()[0].ParameterType;
+ declaringType = (RuntimeType)invoke.GetParametersAsSpan()[0].ParameterType;
  }
  }
  }

src/coreclr/System.Private.CoreLib/src/System/Reflection/Emit/DynamicILGenerator.cs

@@ -94,7 +94,7 @@ public override void Emit(OpCode opcode, MethodInfo meth)
  }
  if (opcode.StackBehaviourPop == StackBehaviour.Varpop)
  {
- stackchange -= meth.GetParametersNoCopy().Length;
+ stackchange -= meth.GetParametersAsSpan().Length;
  }
  // Pop the "this" parameter if the method is non-static,
  // and the instruction is not newobj/ldtoken/ldftn.
@@ -416,7 +416,7 @@ private int GetMemberRefToken(MethodInfo methodInfo, Type[]? optionalParameterTy
  if (rtMeth == null && dm == null)
  throw new ArgumentException(SR.Argument_MustBeRuntimeMethodInfo, nameof(methodInfo));
 
- ParameterInfo[] paramInfo = methodInfo.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> paramInfo = methodInfo.GetParametersAsSpan();
  if (paramInfo != null && paramInfo.Length != 0)
  {
  parameterTypes = new Type[paramInfo.Length];

src/coreclr/System.Private.CoreLib/src/System/Reflection/Emit/RuntimeModuleBuilder.cs

@@ -458,7 +458,7 @@ internal SignatureHelper GetMemberRefSignature(MethodBase? method, int cGenericP
  }
 
  Debug.Assert(method is RuntimeMethodInfo || method is RuntimeConstructorInfo);
- ParameterInfo[] parameters = method.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameters = method.GetParametersAsSpan();
 
  Type[] parameterTypes = new Type[parameters.Length];
  Type[][] requiredCustomModifiers = new Type[parameterTypes.Length][];

src/coreclr/System.Private.CoreLib/src/System/Reflection/MethodBase.CoreCLR.cs

@@ -47,7 +47,7 @@ public abstract partial class MethodBase : MemberInfo
  // used by EE
  private IntPtr GetMethodDesc() { return MethodHandle.Value; }
 
- internal virtual ParameterInfo[] GetParametersNoCopy() { return GetParameters(); }
+ internal virtual ReadOnlySpan<ParameterInfo> GetParametersAsSpan() { return GetParameters(); }
  #endregion
  }
 }

src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeConstructorInfo.CoreCLR.cs

@@ -180,20 +180,11 @@ public override IList<CustomAttributeData> GetCustomAttributesData()
  // This seems to always returns System.Void.
  internal override Type GetReturnType() { return Signature.ReturnType; }
 
- internal override ParameterInfo[] GetParametersNoCopy() =>
+ internal override ReadOnlySpan<ParameterInfo> GetParametersAsSpan() =>
  m_parameters ??= RuntimeParameterInfo.GetParameters(this, this, Signature);
 
- public override ParameterInfo[] GetParameters()
- {
- ParameterInfo[] parameters = GetParametersNoCopy();
-
- if (parameters.Length == 0)
- return parameters;
-
- ParameterInfo[] ret = new ParameterInfo[parameters.Length];
- Array.Copy(parameters, ret, parameters.Length);
- return ret;
- }
+ public override ParameterInfo[] GetParameters() =>
+ GetParametersAsSpan().ToArray();
 
  public override MethodImplAttributes GetMethodImplementationFlags()
  {

src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeCustomAttributeData.cs

@@ -278,7 +278,7 @@ private RuntimeCustomAttributeData(RuntimeModule scope, MetadataToken caCtorToke
  m_ctor = (RuntimeConstructorInfo)scope.ResolveMethod(caCtorToken, attributeType.GenericTypeArguments, null)!.MethodHandle.GetMethodInfo();
  }
 
- ParameterInfo[] parameters = m_ctor.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameters = m_ctor.GetParametersAsSpan();
  if (parameters.Length != 0)
  {
  m_ctorParams = new CustomAttributeCtorParameter[parameters.Length];
@@ -412,7 +412,7 @@ private void Init(object pca)
  // Ensure there is only a single constructor for 'pca', so it is safe to suppress IL2075
  ConstructorInfo[] allCtors = type.GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance);
  Debug.Assert(allCtors.Length == 1);
- Debug.Assert(allCtors[0].GetParameters().Length == 0);
+ Debug.Assert(allCtors[0].GetParametersAsSpan().Length == 0);
 #endif
 
  m_ctor = type.GetConstructors(BindingFlags.Public | BindingFlags.Instance)[0];

src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeEventInfo.cs

@@ -63,10 +63,14 @@ o is RuntimeEventInfo m &&
  #region Object Overrides
  public override string ToString()
  {
- if (m_addMethod == null || m_addMethod.GetParametersNoCopy().Length == 0)
+ ReadOnlySpan<ParameterInfo> parameters;
+ if (m_addMethod == null ||
+ (parameters = m_addMethod.GetParametersAsSpan()).Length == 0)
+ {
  throw new InvalidOperationException(SR.InvalidOperation_NoPublicAddMethod);
+ }
 
- return m_addMethod.GetParametersNoCopy()[0].ParameterType.FormatTypeName() + " " + Name;
+ return parameters[0].ParameterType.FormatTypeName() + " " + Name;
  }
 
  public override bool Equals(object? obj) =>

src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimeMethodInfo.CoreCLR.cs

@@ -240,7 +240,7 @@ public override Type? ReflectedType
  #endregion
 
  #region MethodBase Overrides
- internal override ParameterInfo[] GetParametersNoCopy() =>
+ internal override ReadOnlySpan<ParameterInfo> GetParametersAsSpan() =>
  FetchNonReturnParameters();
 
  public override ParameterInfo[] GetParameters()

src/coreclr/System.Private.CoreLib/src/System/Reflection/RuntimePropertyInfo.cs

@@ -261,38 +261,25 @@ public override MethodInfo[] GetAccessors(bool nonPublic)
  return m_setterMethod;
  }
 
- public override ParameterInfo[] GetIndexParameters()
- {
- ParameterInfo[] indexParams = GetIndexParametersNoCopy();
-
- int numParams = indexParams.Length;
-
- if (numParams == 0)
- return indexParams;
-
- ParameterInfo[] ret = new ParameterInfo[numParams];
-
- Array.Copy(indexParams, ret, numParams);
-
- return ret;
- }
+ public override ParameterInfo[] GetIndexParameters() =>
+ GetIndexParametersSpan().ToArray();
 
- internal ParameterInfo[] GetIndexParametersNoCopy()
+ internal ReadOnlySpan<ParameterInfo> GetIndexParametersSpan()
  {
  // @History - Logic ported from RTM
 
  // No need to lock because we don't guarantee the uniqueness of ParameterInfo objects
  if (m_parameters == null)
  {
  int numParams = 0;
- ParameterInfo[]? methParams = null;
+ ReadOnlySpan<ParameterInfo> methParams = default;
 
  // First try to get the Get method.
  RuntimeMethodInfo? m = GetGetMethod(true);
  if (m != null)
  {
  // There is a Get method so use it.
- methParams = m.GetParametersNoCopy();
+ methParams = m.GetParametersAsSpan();
  numParams = methParams.Length;
  }
  else
@@ -302,7 +289,7 @@ internal ParameterInfo[] GetIndexParametersNoCopy()
 
  if (m != null)
  {
- methParams = m.GetParametersNoCopy();
+ methParams = m.GetParametersAsSpan();
  numParams = methParams.Length - 1;
  }
  }

src/coreclr/System.Private.CoreLib/src/System/RuntimeType.CoreCLR.cs

@@ -2290,7 +2290,7 @@ private static bool FilterApplyMethodBase(
  // Check if argumentTypes supplied
  if (argumentTypes != null)
  {
- ParameterInfo[] parameterInfos = methodBase.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameterInfos = methodBase.GetParametersAsSpan();
 
  if (argumentTypes.Length != parameterInfos.Length)
  {
@@ -2848,8 +2848,7 @@ public override InterfaceMapping GetInterfaceMap([DynamicallyAccessedMembers(Dyn
  {
  ConstructorInfo firstCandidate = candidates[0];
 
- ParameterInfo[] parameters = firstCandidate.GetParametersNoCopy();
- if (parameters == null || parameters.Length == 0)
+ if (firstCandidate.GetParametersAsSpan().IsEmpty)
  {
  return firstCandidate;
  }
@@ -3817,7 +3816,7 @@ private void CreateInstanceCheckThis()
  throw new MissingMethodException(SR.Format(SR.MissingConstructor_Name, FullName));
  }
 
- if (invokeMethod.GetParametersNoCopy().Length == 0)
+ if (invokeMethod.GetParametersAsSpan().Length == 0)
  {
  if (args.Length != 0)
  {

src/coreclr/nativeaot/System.Private.CoreLib/src/CompatibilitySuppressions.xml

@@ -938,7 +938,7 @@
  </Suppression>
  <Suppression>
  <DiagnosticId>CP0002</DiagnosticId>
- <Target>M:System.Reflection.MethodBase.GetParametersNoCopy</Target>
+ <Target>M:System.Reflection.MethodBase.GetParametersAsSpan</Target>
  </Suppression>
  <Suppression>
  <DiagnosticId>CP0002</DiagnosticId>

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Reflection/Extensions/NonPortable/CustomAttributeInheritanceRules.cs

@@ -235,7 +235,7 @@ public sealed override ParameterInfo GetParent(ParameterInfo e)
 
  if (e.Position >= 0)
  {
- return methodParent.GetParametersNoCopy()[e.Position];
+ return methodParent.GetParametersAsSpan()[e.Position];
  }
  else
  {

src/coreclr/nativeaot/System.Private.CoreLib/src/Internal/Reflection/Extensions/NonPortable/CustomAttributeInstantiator.cs

@@ -40,11 +40,11 @@ public static Attribute Instantiate(this CustomAttributeData cad)
  // Find the public constructor that matches the supplied arguments.
  //
  ConstructorInfo? matchingCtor = null;
- ParameterInfo[]? matchingParameters = null;
+ ReadOnlySpan<ParameterInfo> matchingParameters = default;
  IList<CustomAttributeTypedArgument> constructorArguments = cad.ConstructorArguments;
  foreach (ConstructorInfo ctor in attributeType.GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly))
  {
- ParameterInfo[] parameters = ctor.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameters = ctor.GetParametersAsSpan();
  if (parameters.Length != constructorArguments.Count)
  continue;
  int i;
@@ -68,7 +68,7 @@ public static Attribute Instantiate(this CustomAttributeData cad)
  //
  // Found the right constructor. Instantiate the Attribute.
  //
- int arity = matchingParameters!.Length;
+ int arity = matchingParameters.Length;
  object?[] invokeArguments = new object[arity];
  for (int i = 0; i < arity; i++)
  {

src/coreclr/nativeaot/System.Private.CoreLib/src/System/ActivatorImplementation.cs

@@ -99,7 +99,7 @@ public static object CreateInstance(
  binder ??= Type.DefaultBinder;
 
  MethodBase invokeMethod = binder.BindToMethod(bindingAttr, matches.ToArray(), ref args, null, culture, null, out object? state);
- if (invokeMethod.GetParametersNoCopy().Length == 0)
+ if (invokeMethod.GetParametersAsSpan().Length == 0)
  {
  if (args.Length != 0)
  {

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/ConstructorInvoker.cs

@@ -18,7 +18,7 @@ public sealed class ConstructorInvoker
  internal ConstructorInvoker(RuntimeConstructorInfo constructor)
  {
  _methodBaseInvoker = constructor.MethodInvoker;
- _parameterCount = constructor.GetParametersNoCopy().Length;
+ _parameterCount = constructor.GetParametersAsSpan().Length;
  _declaringTypeHandle = constructor.DeclaringType.TypeHandle;
  }
 

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/DynamicInvokeInfo.cs

@@ -61,7 +61,7 @@ public DynamicInvokeInfo(MethodBase method, IntPtr invokeThunk)
 
  // _isValueTypeInstanceMethod = method.DeclaringType?.IsValueType ?? false;
 
- ParameterInfo[] parameters = method.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameters = method.GetParametersAsSpan();
 
  _argumentCount = parameters.Length;
 
@@ -579,7 +579,7 @@ private unsafe ref byte InvokeDirectWithFewArguments(
 
  private unsafe object? GetCoercedDefaultValue(int index, in ArgumentInfo argumentInfo)
  {
- object? defaultValue = Method.GetParametersNoCopy()[index].DefaultValue;
+ object? defaultValue = Method.GetParametersAsSpan()[index].DefaultValue;
  if (defaultValue == DBNull.Value)
  throw new ArgumentException(SR.Arg_VarMissNull, "parameters");
 

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/MethodBase.NativeAot.cs

@@ -16,7 +16,7 @@ public abstract partial class MethodBase : MemberInfo
  public static MethodBase GetCurrentMethod() { throw NotImplemented.ByDesign; } //Implemented by toolchain.
 
  // This is not an api but needs to be declared public so that System.Private.Reflection.Core can access (and override it)
- public virtual ParameterInfo[] GetParametersNoCopy() => GetParameters();
+ public virtual ReadOnlySpan<ParameterInfo> GetParametersAsSpan() => GetParameters();
 
  //
  // MethodBase MetadataDefinitionMethod { get; }

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/MethodInvoker.cs

@@ -17,7 +17,7 @@ public sealed class MethodInvoker
  internal MethodInvoker(RuntimeMethodInfo method)
  {
  _methodBaseInvoker = method.MethodInvoker;
- _parameterCount = method.GetParametersNoCopy().Length;
+ _parameterCount = method.GetParametersAsSpan().Length;
  }
 
  internal MethodInvoker(RuntimeConstructorInfo constructor)

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/BindingFlagSupport/MemberPolicies.cs

@@ -88,8 +88,8 @@ protected static bool AreNamesAndSignaturesEqual(MethodInfo method1, MethodInfo
  if (method1.Name != method2.Name)
  return false;
 
- ParameterInfo[] p1 = method1.GetParametersNoCopy();
- ParameterInfo[] p2 = method2.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> p1 = method1.GetParametersAsSpan();
+ ReadOnlySpan<ParameterInfo> p2 = method2.GetParametersAsSpan();
  if (p1.Length != p2.Length)
  return false;
 

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/BindingFlagSupport/Shared.cs

@@ -40,7 +40,7 @@ public static bool QualifiesBasedOnParameterCount(this MethodBase methodBase, Bi
  #endregion
 
  #region ArgumentTypes
- ParameterInfo[] parameterInfos = methodBase.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameterInfos = methodBase.GetParametersAsSpan();
 
  if (argumentTypes.Length != parameterInfos.Length)
  {

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/CustomAttributes/RuntimeCustomAttributeData.cs

@@ -72,7 +72,7 @@ protected static ConstructorInfo ResolveAttributeConstructor(
  int parameterCount = parameterTypes.Length;
  foreach (ConstructorInfo candidate in attributeType.GetConstructors(BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.DeclaredOnly))
  {
- ParameterInfo[] candidateParameters = candidate.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> candidateParameters = candidate.GetParametersAsSpan();
  if (parameterCount != candidateParameters.Length)
  continue;
 

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/EventInfos/RuntimeEventInfo.cs

@@ -110,7 +110,7 @@ public sealed override MethodInfo RemoveMethod
  public sealed override string ToString()
  {
  MethodInfo addMethod = this.AddMethod;
- ParameterInfo[] parameters = addMethod.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameters = addMethod.GetParametersAsSpan();
  if (parameters.Length == 0)
  throw new InvalidOperationException(); // Legacy: Why is a ToString() intentionally throwing an exception?
  RuntimeParameterInfo runtimeParameterInfo = (RuntimeParameterInfo)(parameters[0]);

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/General/ReflectionCoreCallbacksImplementation.cs

@@ -304,7 +304,7 @@ private static RuntimeMethodInfo LookupMethodForCreateDelegate(RuntimeTypeInfo r
  bindingFlags |= BindingFlags.IgnoreCase;
  }
  RuntimeMethodInfo invokeMethod = runtimeDelegateType.GetInvokeMethod();
- ParameterInfo[] parameters = invokeMethod.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameters = invokeMethod.GetParametersAsSpan();
  int numParameters = parameters.Length;
  Type[] parameterTypes = new Type[numParameters];
  for (int i = 0; i < numParameters; i++)

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/MethodInfos/CustomMethodMapper.cs

@@ -30,7 +30,7 @@ public static MethodBaseInvoker GetCustomMethodInvokerIfNeeded(this MethodBase m
  if (!map.TryGetValue(methodBase.MetadataDefinitionMethod, out CustomMethodInvokerAction? action))
  return null;
 
- ParameterInfo[] parameterInfos = methodBase.GetParametersNoCopy();
+ ReadOnlySpan<ParameterInfo> parameterInfos = methodBase.GetParametersAsSpan();
  Type[] parameterTypes = new Type[parameterInfos.Length];
  for (int i = 0; i < parameterInfos.Length; i++)
  {

src/coreclr/nativeaot/System.Private.CoreLib/src/System/Reflection/Runtime/MethodInfos/RuntimeConstructorInfo.cs

@@ -54,7 +54,7 @@ public sealed override ParameterInfo[] GetParameters()
  return result;
  }
 
- public sealed override ParameterInfo[] GetParametersNoCopy()
+ public sealed override ReadOnlySpan<ParameterInfo> GetParametersAsSpan()
  {
  return RuntimeParameters;
  }