Fixed exception throw on sync completion of async lambda

dotnet · Feb 17, 2024 · 3ef82a9 · 3ef82a9
1 parent 3d09840
commit 3ef82a9
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/src/DotNext.Metaprogramming/Linq/Expressions/AsyncResultExpression.cs b/src/DotNext.Metaprogramming/Linq/Expressions/AsyncResultExpression.cs
@@ -60,6 +60,10 @@ public AsyncResultExpression(bool valueTask)
     /// </remarks>
     public override Type Type => taskType;
 
+    // indicates that AsyncResult cannot throw exception so it can be inlined
+    internal bool IsSimpleResult
+        => AsyncResult is ConstantExpression or ParameterExpression or DefaultExpression;
+
     /// <summary>
     /// Translates this expression into predefined set of expressions
     /// using Lowering technique.

diff --git a/src/DotNext.Metaprogramming/Runtime/CompilerServices/AsyncStateMachineBuilder.cs b/src/DotNext.Metaprogramming/Runtime/CompilerServices/AsyncStateMachineBuilder.cs
@@ -245,9 +245,7 @@ private Expression VisitAsyncResult(AsyncResultExpression expr)
         var prologue = context.CurrentStatement.PrologueCodeInserter();
         expr = (AsyncResultExpression)base.VisitExtension(expr);
 
-        var containsAwait = ExpressionAttributes.Get(expr.AsyncResult) is { ContainsAwait: true };
-
-        if (containsAwait && Task.HasResult)
+        if (Task.HasResult && expr.IsSimpleResult is false)
         {
             ResultVariable ??= Expression.Parameter(Task.ResultType);
             prologue(Expression.Assign(ResultVariable, expr.AsyncResult));