Fix: Config binder generator doesn't generate code when named arguments are out of order

src/libraries/Microsoft.Extensions.Configuration.Binder/gen/Parser/ConfigurationBinder.cs

@@ -77,7 +77,7 @@ private void ParseBindInvocation_ConfigurationBinder(BinderInvocation invocation
                     _ => throw new InvalidOperationException()
                 };
 
-                IArgumentOperation instanceArg = operation.Arguments[instanceIndex];
+                IArgumentOperation instanceArg = GetArgumentForParameterAtIndex(operation.Arguments, instanceIndex);
                 if (instanceArg.Parameter.Type.SpecialType != SpecialType.System_Object)
                 {
                     return;
@@ -119,6 +119,19 @@ private void ParseBindInvocation_ConfigurationBinder(BinderInvocation invocation
                     };
             }
 
+            private static IArgumentOperation GetArgumentForParameterAtIndex(ImmutableArray<IArgumentOperation> arguments, int parameterIndex)
+            {
+                foreach (var argument in arguments)
+                {
+                    if (argument.Parameter?.Ordinal == parameterIndex)
+                    {
+                        return argument;
+                    }
+                }
+
+                throw new InvalidOperationException();
+            }
+
             private void ParseGetInvocation(BinderInvocation invocation)
             {
                 IInvocationOperation operation = invocation.Operation!;
@@ -158,7 +171,7 @@ private void ParseGetInvocation(BinderInvocation invocation)
                 }
                 else
                 {
-                    ITypeOfOperation? typeOfOperation = operation.Arguments[1].ChildOperations.FirstOrDefault() as ITypeOfOperation;
+                    ITypeOfOperation? typeOfOperation = GetArgumentForParameterAtIndex(operation.Arguments, 1).ChildOperations.FirstOrDefault() as ITypeOfOperation;
                     type = typeOfOperation?.TypeOperand;
 
                     if (paramCount is 2)
@@ -218,7 +231,7 @@ private void ParseGetValueInvocation(BinderInvocation invocation)
                         return;
                     }
 
-                    ITypeOfOperation? typeOfOperation = operation.Arguments[1].ChildOperations.FirstOrDefault() as ITypeOfOperation;
+                    ITypeOfOperation? typeOfOperation = GetArgumentForParameterAtIndex(operation.Arguments, 1).ChildOperations.FirstOrDefault() as ITypeOfOperation;
                     type = typeOfOperation?.TypeOperand;
 
                     if (paramCount is 3)

src/libraries/Microsoft.Extensions.Configuration.Binder/tests/SourceGenerationTests/Baselines/ConfigurationBinder/Bind_NamedParameters.generated.txt

@@ -0,0 +1,170 @@
+// <auto-generated/>
+#nullable enable
+#pragma warning disable CS0612, CS0618 // Suppress warnings about [Obsolete] member usage in generated code.
+
+namespace System.Runtime.CompilerServices
+{
+    using System;
+    using System.CodeDom.Compiler;
+
+    [GeneratedCode("Microsoft.Extensions.Configuration.Binder.SourceGeneration", "42.42.42.42")]
+    [AttributeUsage(AttributeTargets.Method, AllowMultiple = true)]
+    file sealed class InterceptsLocationAttribute : Attribute
+    {
+        public InterceptsLocationAttribute(string filePath, int line, int column)
+        {
+        }
+    }
+}
+
+namespace Microsoft.Extensions.Configuration.Binder.SourceGeneration
+{
+    using Microsoft.Extensions.Configuration;
+    using System;
+    using System.CodeDom.Compiler;
+    using System.Collections.Generic;
+    using System.Globalization;
+    using System.Runtime.CompilerServices;
+
+    [GeneratedCode("Microsoft.Extensions.Configuration.Binder.SourceGeneration", "42.42.42.42")]
+    file static class BindingExtensions
+    {
+        #region IConfiguration extensions.
+        /// <summary>Attempts to bind the given object instance to configuration values by matching property names against configuration keys recursively.</summary>
+        [InterceptsLocation(@"src-0.cs", 12, 33)]
+        public static void Bind_ProgramMyClass(this IConfiguration configuration, object? instance)
+        {
+            if (configuration is null)
+            {
+                throw new ArgumentNullException(nameof(configuration));
+            }
+
+            if (instance is null)
+            {
+                return;
+            }
+
+            var typedObj = (Program.MyClass)instance;
+            BindCore(configuration, ref typedObj, binderOptions: null);
+        }
+        #endregion IConfiguration extensions.
+
+        #region Core binding extensions.
+        private readonly static Lazy<HashSet<string>> s_configKeys_ProgramMyClass = new(() => new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "MyString", "MyInt", "MyList", "MyDictionary", "MyComplexDictionary" });
+
+        public static void BindCore(IConfiguration configuration, ref List<int> instance, BinderOptions? binderOptions)
+        {
+            foreach (IConfigurationSection section in configuration.GetChildren())
+            {
+                if (section.Value is string value)
+                {
+                    instance.Add(ParseInt(value, () => section.Path));
+                }
+            }
+        }
+
+        public static void BindCore(IConfiguration configuration, ref Dictionary<string, string> instance, BinderOptions? binderOptions)
+        {
+            foreach (IConfigurationSection section in configuration.GetChildren())
+            {
+                if (section.Value is string value)
+                {
+                    instance[section.Key] = value;
+                }
+            }
+        }
+
+        public static void BindCore(IConfiguration configuration, ref Dictionary<string, Program.MyClass2> instance, BinderOptions? binderOptions)
+        {
+            foreach (IConfigurationSection section in configuration.GetChildren())
+            {
+                if (!(instance.TryGetValue(section.Key, out Program.MyClass2? element) && element is not null))
+                {
+                    element = new Program.MyClass2();
+                }
+                instance[section.Key] = element;
+            }
+        }
+
+        public static void BindCore(IConfiguration configuration, ref Program.MyClass instance, BinderOptions? binderOptions)
+        {
+            ValidateConfigurationKeys(typeof(Program.MyClass), s_configKeys_ProgramMyClass, configuration, binderOptions);
+
+            instance.MyString = configuration["MyString"]!;
+
+            if (configuration["MyInt"] is string value1)
+            {
+                instance.MyInt = ParseInt(value1, () => configuration.GetSection("MyInt").Path);
+            }
+
+            if (AsConfigWithChildren(configuration.GetSection("MyList")) is IConfigurationSection section2)
+            {
+                List<int>? temp4 = instance.MyList;
+                temp4 ??= new List<int>();
+                BindCore(section2, ref temp4, binderOptions);
+                instance.MyList = temp4;
+            }
+
+            if (AsConfigWithChildren(configuration.GetSection("MyDictionary")) is IConfigurationSection section5)
+            {
+                Dictionary<string, string>? temp7 = instance.MyDictionary;
+                temp7 ??= new Dictionary<string, string>();
+                BindCore(section5, ref temp7, binderOptions);
+                instance.MyDictionary = temp7;
+            }
+
+            if (AsConfigWithChildren(configuration.GetSection("MyComplexDictionary")) is IConfigurationSection section8)
+            {
+                Dictionary<string, Program.MyClass2>? temp10 = instance.MyComplexDictionary;
+                temp10 ??= new Dictionary<string, Program.MyClass2>();
+                BindCore(section8, ref temp10, binderOptions);
+                instance.MyComplexDictionary = temp10;
+            }
+        }
+
+
+        /// <summary>If required by the binder options, validates that there are no unknown keys in the input configuration object.</summary>
+        public static void ValidateConfigurationKeys(Type type, Lazy<HashSet<string>> keys, IConfiguration configuration, BinderOptions? binderOptions)
+        {
+            if (binderOptions?.ErrorOnUnknownConfiguration is true)
+            {
+                List<string>? temp = null;
+
+                foreach (IConfigurationSection section in configuration.GetChildren())
+                {
+                    if (!keys.Value.Contains(section.Key))
+                    {
+                        (temp ??= new List<string>()).Add($"'{section.Key}'");
+                    }
+                }
+
+                if (temp is not null)
+                {
+                    throw new InvalidOperationException($"'ErrorOnUnknownConfiguration' was set on the provided BinderOptions, but the following properties were not found on the instance of {type}: {string.Join(", ", temp)}");
+                }
+            }
+        }
+
+        public static IConfiguration? AsConfigWithChildren(IConfiguration configuration)
+        {
+            foreach (IConfigurationSection _ in configuration.GetChildren())
+            {
+                return configuration;
+            }
+            return null;
+        }
+
+        public static int ParseInt(string value, Func<string?> getPath)
+        {
+            try
+            {
+                return int.Parse(value, NumberStyles.Integer, CultureInfo.InvariantCulture);
+            }
+            catch (Exception exception)
+            {
+                throw new InvalidOperationException($"Failed to convert configuration value at '{getPath()}' to type '{typeof(int)}'.", exception);
+            }
+        }
+        #endregion Core binding extensions.
+    }
+}