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Infer delegate type from lambda expression with explicit return statements without expressions #56236

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merged 2 commits into from
Sep 14, 2021
Merged

Infer delegate type from lambda expression with explicit return statements without expressions #56236

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Infer delegate type from lambda expression with explicit return state…
cston Sep 8, 2021
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More tests
cston Sep 13, 2021
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2 changes: 1 addition & 1 deletion src/Compilers/CSharp/Portable/BoundTree/UnboundLambda.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -624,7 +624,7 @@ private static TypeWithAnnotations DelegateReturnTypeWithAnnotations(MethodSymbo
returnType = inferredReturnType.TypeWithAnnotations;
returnRefKind = inferredReturnType.RefKind;

if (!returnType.HasType && returnTypes.Count > 0)
if (!returnType.HasType && inferredReturnType.NumExpressions > 0)
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@AlekseyTs AlekseyTs Sep 9, 2021 •
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if (!returnType.HasType && inferredReturnType.NumExpressions > 0)

It looks like the change only affects scenarios that involve return statements without expressions. Is this correct? If so, consider adjusting commit's title/description as right now it feels too broad. #Closed

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@AlekseyTs AlekseyTs Sep 9, 2021 •
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inferredReturnType.NumExpressions > 0

It looks like all added tests are success tests. Do we have failure tests for this condition? Specifically when there is a mix of returns with and without an expression. #Closed

{
return null;
}
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45 changes: 45 additions & 0 deletions src/Compilers/CSharp/Test/Semantic/Semantics/DelegateTypeTests.cs
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Expand Up @@ -3804,6 +3804,51 @@ static void Main()
Assert.True(HaveMatchingSignatures(((INamedTypeSymbol)typeInfo.Type!).DelegateInvokeMethod!, method));
}

[WorkItem(55320, "https://github.com/dotnet/roslyn/issues/55320")]
[Fact]
public void InferredReturnType_01()
{
var source =
@"using System;
class Program
{
static void Main()
{
Report(() => { return; });
Report((bool b) => { if (b) return; });
Report((bool b) => { if (b) return; else return; });
}
static void Report(object obj) => Console.WriteLine(obj.GetType());
}";
CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput:
@"System.Action
System.Action`1[System.Boolean]
System.Action`1[System.Boolean]
");
}

[Fact]
public void InferredReturnType_02()
{
var source =
@"using System;
class Program
{
static void Main()
{
Report(async () => { return; });
Report(async (bool b) => { if (b) return; });
Report(async (bool b) => { if (b) return; else return; });
}
static void Report(object obj) => Console.WriteLine(obj.GetType());
}";
CompileAndVerify(source, options: TestOptions.ReleaseExe, expectedOutput:
@"System.Func`1[System.Threading.Tasks.Task]
System.Func`2[System.Boolean,System.Threading.Tasks.Task]
System.Func`2[System.Boolean,System.Threading.Tasks.Task]
");
}

[Fact]
public void TypeInference_Constraints_01()
{
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