Could not inject EventInvoker method

This issue seems to be the same as in #316 and is as of now present in PropertyChanged 2.5.6 / Fody 3.0.3 when used in Xamarin.Forms solutions, temporary workaround has been to downgrade the respective packages to 2.2.10 and 2.5.0. Minimal repro has been uploaded here. I’ve yet to test this issue on a Windows PC, however both VSMac and msbuild fails. I’m currently on Xamarin.Forms 3.0.0.446417.

Steps to reproduce:

1. Create a blank Xamarin.Forms application (netstandard 2.0 in this case).
2. Add PropertyChanged 2.5.6 package, adding Fody 3.0.3.
3. Add FodyWeavers.xml to projects, add weaver <PropertyChanged/> or <PropertyChanged EventInvokerNames="RaisePropertyChanged" />.
4. Build either with VS or msbuild.

Full msbuild log:

MSBUILD : error : Fody: An unhandled exception occurred:
MSBUILD : error : Exception:
MSBUILD : error : Failed to execute weaver /Users/arnemolland/.nuget/packages/propertychanged.fody/2.5.6/netclassicweaver/PropertyChanged.Fody.dll
MSBUILD : error : Type:
MSBUILD : error : System.Exception
MSBUILD : error : StackTrace:
MSBUILD : error :   at InnerWeaver.ExecuteWeavers () [0x0007a] in C:\projects\fody\FodyIsolated\InnerWeaver.cs:208 
MSBUILD : error :   at InnerWeaver.Execute () [0x0004d] in C:\projects\fody\FodyIsolated\InnerWeaver.cs:103 
MSBUILD : error : Source:
MSBUILD : error : FodyIsolated
MSBUILD : error : TargetSite:
MSBUILD : error : Void ExecuteWeavers()
MSBUILD : error : Could not inject EventInvoker method on type 'FodyRepro.App'. It is possible you are inheriting from a base class and have not correctly set 'EventInvokerNames' or you are using a explicit PropertyChanged event and the event field is not visible to this instance. Either correct 'EventInvokerNames' or implement your own EventInvoker on this class. If you want to suppress this place a [DoNotNotifyAttribute] on FodyRepro.App.
MSBUILD : error : Type:
MSBUILD : error : Fody.WeavingException
MSBUILD : error : StackTrace:
MSBUILD : error :   at ModuleWeaver.InjectMethod (Mono.Cecil.TypeDefinition targetType, InvokerTypes& invokerType) [0x0005e] in C:\projects\propertychanged\PropertyChanged.Fody\MethodInjector.cs:102 
MSBUILD : error :   at ModuleWeaver.AddOnPropertyChangedMethod (Mono.Cecil.TypeDefinition targetType) [0x0005c] in C:\projects\propertychanged\PropertyChanged.Fody\MethodInjector.cs:28 
MSBUILD : error :   at ModuleWeaver.FindMethodsForNodes () [0x00026] in C:\projects\propertychanged\PropertyChanged.Fody\MethodFinder.cs:237 
MSBUILD : error :   at ModuleWeaver.Execute () [0x00042] in C:\projects\propertychanged\PropertyChanged.Fody\ModuleWeaver.cs:18 
MSBUILD : error :   at InnerWeaver.ExecuteWeavers () [0x0006b] in C:\projects\fody\FodyIsolated\InnerWeaver.cs:204 
MSBUILD : error : Source:
MSBUILD : error : PropertyChanged.Fody
MSBUILD : error : TargetSite:
MSBUILD : error : Mono.Cecil.MethodDefinition InjectMethod(Mono.Cecil.TypeDefinition, InvokerTypes ByRef)

[ltrzesniewski]

@arnemolland Ok so I’ve installed Xamarin and tested your repro.

You’ve used the following config:

<?xml version="1.0" encoding="utf-8"?>
<Weavers>
    <PropertyChanged EventInvokerNames="RaisePropertyChanged" />
</Weavers>

But the issue here is that App inherits from Application which ultimately inherits from BindableObject which implements INotifyPropertyChanged, but it declares an event invoker named OnPropertyChanged.

=> if you put EventInvokerNames="OnPropertyChanged" in your config or if you remove the EventInvokerNames attribute altogether, the project compiles just fine.

[ltrzesniewski]

You’re welcome. Your repro compiled fine when I removed the attribute, so if you manage to extract an example which fails without the attribute, feel free to post it.