Don't use Delegate.Method in ServiceDescriptor
#114008
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The problem with this API is that in a trimmed app, accessing `Method` on a delegate type forces trimming to consider all delegate targets also targets of reflection (since we're grabbing a `MethodInfo` for whatever is the target). We do try to optimize this and only consider targets of the same delegate type, but in this case it means `Func<T, U>` and `Func<T,U,V>` which are very popular delegate types. Avoiding `Delegate.Method` is a 0.8% size saving for the Microsoft Store app. The differences are: * Originally this was calling `ToString` on the `MethodInfo`, which returns the name and signature of the method. I'm replacing this with `FullName` of the owning type and the name of the method. This is both more information and less information - we get owning type, we lose signature. It feels more useful nevertheless. * When the app is trimmed and `StackTraceSupport` feature switch is set to false, this will return question marks. The 0.8% size savings is present no matter the value of the `StackTraceSupport` switch.
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Pull Request Overview
This PR updates ServiceDescriptor’s ToString implementation for service factories to avoid using Delegate.Method, reducing trimming impact and saving app size.
- Replaces calls to Delegate.Method.ToString with explicit formatting of the declaring type’s full name and method name.
- Uses conditional compilation (#if NET9_0_OR_GREATER) to support newer diagnostics while retaining legacy behavior.
| @@ -262,7 +263,17 @@ public override string ToString() | |||
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| if (KeyedImplementationFactory != null) | |||
| { | |||
| return lifetime + $"{nameof(KeyedImplementationFactory)}: {KeyedImplementationFactory.Method}"; | |||
| #if NET9_0_OR_GREATER | |||
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The logic for retrieving and formatting method information for KeyedImplementationFactory is duplicated for ImplementationFactory. Consider refactoring this logic into a shared helper method to reduce duplication and improve maintainability.
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| @@ -276,7 +287,17 @@ public override string ToString() | |||
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| if (ImplementationFactory != null) | |||
| { | |||
| return lifetime + $"{nameof(ImplementationFactory)}: {ImplementationFactory.Method}"; | |||
| #if NET9_0_OR_GREATER | |||
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The same method info retrieval logic is used here as for KeyedImplementationFactory. Refactoring this logic into a common helper can ensure consistency and reduce maintenance effort.
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Tagging subscribers to this area: @dotnet/area-extensions-dependencyinjection |
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Some test failures: |
I've updated the tests to expect the new format, CI looks good now. |
The problem with this API is that in a trimmed app, accessing
Methodon a delegate type forces trimming to consider all delegate targets also targets of reflection (since we're grabbing aMethodInfofor whatever is the target). We do try to optimize this and only consider targets of the same delegate type, but in this case it meansFunc<T, U>andFunc<T,U,V>which are very popular delegate types. AvoidingDelegate.Methodis a 0.8% size saving for the Microsoft Store app.The differences are:
ToStringon theMethodInfo, which returns the name and signature of the method. I'm replacing this withFullNameof the owning type and the name of the method. This is both more information and less information - we get owning type, we lose signature. It feels more useful nevertheless.StackTraceSupportfeature switch is set to false, this will return question marks.The 0.8% size savings is present no matter the value of the
StackTraceSupportswitch.