Use nameof where possible.

src/Avalonia.Animation/IterationCount.cs

@@ -44,7 +44,7 @@ namespace Avalonia.Animation
         {
             if (type > IterationType.Infinite)
             {
-                throw new ArgumentException("Invalid value", "type");
+                throw new ArgumentException("Invalid value", nameof(type));
             }
 
             _type = type;

src/Avalonia.Base/Collections/AvaloniaDictionary.cs

@@ -148,7 +148,7 @@ namespace Avalonia.Collections
         {
             if (_inner.TryGetValue(key, out TValue value))
             {
-                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Count"));
+                PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Count)));
                 PropertyChanged?.Invoke(this, new PropertyChangedEventArgs($"Item[{key}]"));
 
                 if (CollectionChanged != null)
@@ -209,7 +209,7 @@ namespace Avalonia.Collections
 
         private void NotifyAdd(TKey key, TValue value)
         {
-            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Count"));
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Count)));
             PropertyChanged?.Invoke(this, new PropertyChangedEventArgs($"Item[{key}]"));
             
 

src/Avalonia.Base/Collections/AvaloniaList.cs

@@ -511,7 +511,7 @@ namespace Avalonia.Collections
         /// </summary>
         private void NotifyCountChanged()
         {
-            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Count"));
+            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(Count)));
         }
 
         /// <summary>

src/Avalonia.Controls/Calendar/DatePicker.cs

@@ -954,7 +954,7 @@ namespace Avalonia.Controls
                 }
                 else
                 {
-                    var dateValidationError = new DatePickerDateValidationErrorEventArgs(new ArgumentOutOfRangeException("text", "SelectedDate value is not valid."), text);
+                    var dateValidationError = new DatePickerDateValidationErrorEventArgs(new ArgumentOutOfRangeException(nameof(text), "SelectedDate value is not valid."), text);
                     OnDateValidationError(dateValidationError);
 
                     if (dateValidationError.ThrowException)

src/Avalonia.Controls/GridLength.cs

@@ -56,12 +56,12 @@ namespace Avalonia.Controls
         {
             if (value < 0 || double.IsNaN(value) || double.IsInfinity(value))
             {
-                throw new ArgumentException("Invalid value", "value");
+                throw new ArgumentException("Invalid value", nameof(value));
             }
 
             if (type < GridUnitType.Auto || type > GridUnitType.Star)
             {
-                throw new ArgumentException("Invalid value", "type");
+                throw new ArgumentException("Invalid value", nameof(type));
             }
 
             _type = type;

src/Avalonia.Controls/NumericUpDown/NumericUpDown.cs

@@ -487,7 +487,7 @@ namespace Avalonia.Controls
         {
             if (e == null)
             {
-                throw new ArgumentNullException("e");
+                throw new ArgumentNullException(nameof(e));
             }
 
             var handler = Spinned;

src/Avalonia.Styling/Styling/Setter.cs

@@ -69,7 +69,7 @@ namespace Avalonia.Styling
                 {
                     throw new ArgumentException(
                         "Cannot assign a control to Setter.Value. Wrap the control in a <Template>.",
-                        "value");
+                        nameof(value));
                 }
 
                 _value = value;