Fix #74 Prevent a crash when there's a complex expression to the left…

… of the dot in an extension method

src/Zomp.SyncMethodGenerator/AsyncToSyncRewriter.cs

@@ -133,7 +133,7 @@ static BinaryExpressionSyntax CheckNull(ExpressionSyntax expr) => BinaryExpressi
             CastExpression(NullableType(IdentifierName(SystemObject)), expr).AppendSpace(),
             LiteralExpression(SyntaxKind.NullLiteralExpression).PrependSpace());
 
-        var argumentType = GetSymbol(leftOfTheDot) ?? throw new InvalidOperationException("Can't process");
+        var argumentType = GetSymbol(node.Expression) ?? throw new InvalidOperationException("Can't process");
         var funcArgumentType = GetReturnType(argumentType);
 
         IdentifierNameSyntax toCheckForNullExpr;

tests/Generator.Tests/ExtensionMethodTests.cs

@@ -0,0 +1,73 @@
+namespace Generator.Tests;
+
+public class ExtensionMethodTests
+{
+    [Fact]
+    public Task UnwrapGenericExtensionMethod() => """
+using System.Drawing;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Zomp.SyncMethodGenerator.IntegrationTests
+{
+    using Extensi.ons123;
+    partial class Extensions
+    {
+        [CreateSyncVersion]
+        public static async Task HasGenericExtensionAsync(object o, CancellationToken ct)
+        {
+            var z = o.TryGetValue<Point>(out var item);
+        }
+
+        [CreateSyncVersion]
+        public static async Task HasGeneric2ExtensionAsync(object o, CancellationToken ct)
+        {
+            var z = o.TryGetValue<Point, PointF>(out var _, out var _1);
+        }
+    }
+}
+
+namespace Extensi.ons123
+{
+    internal static class MyExtensionClass
+    {
+        public static bool TryGetValue<T>(this object _, out T? item)
+        {
+            item = default;
+            return false;
+        }
+
+        public static bool TryGetValue<T1, T2>(this object _, out T1? item1, out T2? item2)
+        {
+            item1 = default;
+            item2 = default;
+            return false;
+        }
+    }
+}
+""".Verify(sourceType: SourceType.Full);
+
+    [Fact]
+    public Task LeftOfTheDotTest() => """
+namespace Tests;
+
+internal class Bar
+{
+    public static Bar Create() => new Bar();
+}
+
+partial class Class
+{
+    [Zomp.SyncMethodGenerator.CreateSyncVersion]
+    public async Task MethodAsync()
+    {
+        _ = Bar.Create()?.DoSomething();
+    }
+}
+
+internal static class BarExtension
+{
+    public static Bar DoSomething(this Bar bar) => bar;
+}
+""".Verify(sourceType: SourceType.Full);
+}

tests/Generator.Tests/Snapshots/ExtensionMethodTests.LeftOfTheDotTest#Tests.Class.MethodAsync.g.verified.cs

@@ -0,0 +1,11 @@
+//HintName: Tests.Class.MethodAsync.g.cs
+// <auto-generated/>
+#nullable enable
+namespace Tests;
+partial class Class
+{
+    public void Method()
+    {
+        _ = ((global::System.Func<global::Tests.Bar?,global::Tests.Bar?>)((param)=>(object?)param == null?(global::Tests.Bar?)null: global::Tests.BarExtension.DoSomething(param)))(global::Tests.Bar.Create());
+    }
+}

tests/Generator.Tests/UnitTests.cs

@@ -643,51 +643,6 @@ These comments shouldn't show
 #endregion
 }
 
-""".Verify(sourceType: SourceType.Full);
-
-    [Fact]
-    public Task UnwrapGenericExtensionMethod() => """
-using System.Drawing;
-using System.Threading;
-using System.Threading.Tasks;
-
-namespace Zomp.SyncMethodGenerator.IntegrationTests
-{
-    using Extensi.ons123;
-    partial class Extensions
-    {
-        [CreateSyncVersion]
-        public static async Task HasGenericExtensionAsync(object o, CancellationToken ct)
-        {
-            var z = o.TryGetValue<Point>(out var item);
-        }
-
-        [CreateSyncVersion]
-        public static async Task HasGeneric2ExtensionAsync(object o, CancellationToken ct)
-        {
-            var z = o.TryGetValue<Point, PointF>(out var _, out var _1);
-        }
-    }
-}
-
-namespace Extensi.ons123
-{
-    internal static class MyExtensionClass
-    {
-        public static bool TryGetValue<T>(this object _, out T? item)
-        {
-            item = default;
-            return false;
-        }
-
-        public static bool TryGetValue<T1, T2>(this object _, out T1? item1, out T2? item2)
-        {
-            item1 = default;
-            item2 = default;
-            return false;
-        }
-    }
-}
 """.Verify(sourceType: SourceType.Full);
 
 #if NETCOREAPP1_0_OR_GREATER