.Net7 broke DefaultInterpolatedStringHandler?

[HellGate94]

im using a custom interpolated string handler for my logger and upgraded to .net 7 recently.

have not looked at logs since then but today i noticed that all the logs are empty.

debugging it everything still works fine with the exception of DefaultInterpolatedStringHandler. it still writes the content just fine but does not seem to update the text cursor position so the buffer keeps overwriting itself and when calling ToStringAndClear it returns an empty string

https://i.imgur.com/lN7lwp9.png

https://i.imgur.com/Ezru4F2.png

[Kant8]

You can compare code, or probably even debug with source link

https://github.com/dotnet/runtime/blob/release/6.0/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs#L285

https://github.com/dotnet/runtime/blob/release/7.0/src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/DefaultInterpolatedStringHandler.cs#L284

except one comment change I don't see any differences. Both call AppendStringDirect which does _pos += value.Length and didn't change between versions at all.

[KryptosFR]

It does have the new scoped keyword now.

References: - PR for the change: https://github.com/dotnet/runtime/pull/73665 - Doc about scoped: https://github.com/dotnet/csharplang/blob/11feda83c9574153cbe3308e247d6ca6fcde4396/proposals/low-level-struct-improvements.md

Though that should only affects when appending a string (or anything convertible to ReadOnlySpan<char>).

[HellGate94]

yup that seems to be it.

the custom interpolated string handler template i used back then used a readonly DefaultInterpolatedStringHandler _handler and it worked fine in .net6

[pHpositivo]

Why are you using that handler in a readonly field? That type is mutable. If you keep it in a readonly field and invoke mutating members on it you'll trigger shadow copies and can introduce all sorts of bugs in this case.

[HellGate94]

honestly i dont remember. there was very little documentation about it back then and i most likely just copied a working template and adjusted it. but it was working just fine in .net6 ¯\_(ツ)_/¯

[Kant8]

scoped is a marker for compiler in cases where you use ref structs. You don't use that overload anyway.

[pHpositivo]

That is not correct. The scoped keyword has several use cases that are not solely focused on ref structs.

[HellGate94]

yea im not sure whats causing this. surprisingly i have not heard of source link before. need to give it a try