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  Rolf Kristensen September 2, 2022 · Edited 0

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  Think .NET7 should perform full-trim by default, but when detecting assemblies with warnings, then it should only perform partial triming of the assembly, unless the assembly is explictly marked

  <IsTrimmable>true</IsTrimmable>

• 

  Rolf Kristensen August 21, 2022 1

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  Is there a way to mark an assembly, that it should not be trimmed?

  Will the NET7 linker recognize this assembly-attribute:

  [AssemblyMetadata(“IsTrimmable”, “False”)]

• 

  Ion Robu August 10, 2022 0

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  Regarding

  MaxInteger[T](System.Collections.Generic.IEnumerable`1[T])' violates the constraint of type parameter 'T' exception

  Automapper issue, I used myget version (11.0.2) and it worked. Is a workaround until issue will be solved with a new nuget package.
  https://myget.org/feed/automapperdev/package/nuget/AutoMapper

• 

  William Liu August 10, 2022 2

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  There could be a type error in the demo of simplified-ordering-with-system-linq

  The new code might be OrderDescending.

  var data = new[] { 2, 1, 3 };
  var sorted = data.Order();
  var sortedDesc = data.OrderDescending();

• 

  Jonathan Vella August 10, 2022 0

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  The below paragraph is written twice in this section.

  For example, an app that uses Newtonsoft.Json or System.Text.Json without source generation to serialize and deserialize a type in the user project may have functioned before the change, because types in the user project were fully preserved. However, one or more trim warnings (warning codes ILxxxx) would have been present. Now, types in the user project are trimmed, and serialization may fail or produce unexpected results.

  Read more

  The below paragraph is written twice in this section.

  For example, an app that uses Newtonsoft.Json or System.Text.Json without source generation to serialize and deserialize a type in the user project may have functioned before the change, because types in the user project were fully preserved. However, one or more trim warnings (warning codes ILxxxx) would have been present. Now, types in the user project are trimmed, and serialization may fail or produce unexpected results.

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• 

  Blake Mitchell August 9, 2022 0

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  What is LibraryImport and how does it differ from DllImport? The example shows basically no difference and the description doesn’t say. Where is the documentation for it? Also, partial is a C# language feature and is not in F#, so does LibraryImport support F#?

  • 

    Steve August 10, 2022 · Edited 0

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    A DllImport will be compiled to an IL stub, and when the first time a DllImport method is called, the runtime generates code for marshalling data. This works fine if code does not get trimmed. But if trimming is enabled, some types for marshalling will be trimmed away because the compiler does not know whether a type will be referenced by the marshalling code which is generated at the runtime.
    LibraryImport is a source generator...

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    A DllImport will be compiled to an IL stub, and when the first time a DllImport method is called, the runtime generates code for marshalling data. This works fine if code does not get trimmed. But if trimming is enabled, some types for marshalling will be trimmed away because the compiler does not know whether a type will be referenced by the marshalling code which is generated at the runtime.
    LibraryImport is a source generator that produces all marshalling code at compile time, so types won’t be trimmed by the compiler accidentally.

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    • 

      Jeremy Koritzinsky August 10, 2022 0

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      As others have mentioned, LibraryImport is an attribute that a built-in source generator recognizes to generate interop code at compile-time instead of at runtime. This provides a few benefits:

      Additionally, the flexibility of the new model enables us to both add support for newer .NET types in interop and allowing developers like yourself to write your own interop support for either your types or built-in types with specific behaviors for your scenarios without having to allocate...

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      As others have mentioned, LibraryImport is an attribute that a built-in source generator recognizes to generate interop code at compile-time instead of at runtime. This provides a few benefits:

      • The marshalling code is generated at compile-time, so it can be seen with Go-to-Definition in Visual Studio. Additionally, it can be stepped into, unlike marshalling code generated when using DllImport.
      • The marshalling code versions with the TFM you compile against, not the TFM you run against. This makes it easier to know what your code will do and limits our concerns around breaking changes as any new changes in behavior will be part of a new target framework version that users will have to explicitly opt into by compiling against it.

      Additionally, the flexibility of the new model enables us to both add support for newer .NET types in interop and allowing developers like yourself to write your own interop support for either your types or built-in types with specific behaviors for your scenarios without having to allocate or box or having limitations around value types. For example, LibraryImport-based P/Invokes support Span<T> and ReadOnlySpan<T> parameters and return values similar to arrays. Additionally, our new model also enabled us to easily support marshalling jagged arrays, which is not supported in the DllImport system.

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  • 

    Michael Taylor August 10, 2022 0

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    That feature is talked about at the top of the article under . The gist of it is that it is used as an indicator for source generators. Today if you use then nothing happens until runtime outside the compiler flagging the method as external (I believe). When the method is actually called there is overhead as the attribute values are translated into the actual call (e.g. should we search for an exact name...

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    That feature is talked about at the top of the article under LibraryImport P/Invoke source generator. The gist of it is that it is used as an indicator for source generators. Today if you use DllImport then nothing happens until runtime outside the compiler flagging the method as external (I believe). When the method is actually called there is overhead as the attribute values are translated into the actual call (e.g. should we search for an exact name or do a wildcard search, ANSI or Unicode, etc). This slows the call down.

    Source generators are a newer feature of C# and allow the compiler to auto-generate code on the fly. They are becoming heavily used in boilerplate code like implementing INotifyPropertyChanged and logging. You should read up on them if you’re interested. But for a source generator to work it generally needs some sort of indicator to look for, attributes are common. Hence the LibraryImport is an indicator that tells the source generator to generate, at compile time, the necessary code to make the native call at runtime. This increases your code size a little bit but puts a lot of the heavy lifting into the compilation process so the runtime call is fast. Rather than picking the attribute apart at runtime it does so at compile time. The net effect is faster runtime code in many cases.

    They could have used the existing DllImport attribute (hence why they work similar) but then the compiler would be auto-generating code that you might not wanted (and might break things if a particular scenario isn’t working in the generator). So a new attribute avoids problems. In theory you could find all references to DllImport and convert them and then verify your code still works. The compiler just won’t do it automatically.

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  • 

    Yegor Stepanov August 10, 2022 0

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    As I understand, DllImportGenerator(experimental compile-time DllImport) has been renamed to LibraryImport.

    It eliminates generating stubs on the first invoke and doesn’t use Reflection.

    F# doesn’t support it because F# doesn’t support SourceGenerators yet.

  • 

    Kirsan August 9, 2022 0

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    +1 about LibraryImport above DllImport benefits.

• 

  Holger Schwichtenberg (www.DOTNET-DOKTOR.de) August 9, 2022 · Edited 0

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  This sample does not compile in .NET 7 Preview 7 SDK:

  <code>

  Error: SYSLIB1050 Method 'ToLower' is contained in a type 'Native' that is not marked 'partial'. P/Invoke source generation will ignore method 'ToLower'.

  Shouldn't your sample be like that?

  <code>

  Read more

  This sample does not compile in .NET 7 Preview 7 SDK:

  public static class Native
  {
      [LibraryImport(nameof(Native), StringMarshalling = StringMarshalling.Utf16)]
      public static partial string ToLower(string str);
  }

  Error: SYSLIB1050 Method ‘ToLower’ is contained in a type ‘Native’ that is not marked ‘partial’. P/Invoke source generation will ignore method ‘ToLower’.

  Shouldn’t your sample be like that?

  public static partial class Native
  {
      [LibraryImport(nameof(Native), StringMarshalling = StringMarshalling.Utf16)]
      public static partial string ToLower(string str);
  }

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• 

  Holger Schwichtenberg (www.DOTNET-DOKTOR.de) August 9, 2022 · Edited 0

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  The sample show in the section “Support for Unix file modes” does not compile with the .NET 7 Preview 7 SDK.
  The enum UnixFileMode is not in System.IO. The methods File.GetUnixFileMode() and File.SetUnixFileMode() are not found.
  Which extra package is needed for this?

• 

  Beau Gosse August 9, 2022 · Edited 0

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  Does the breaking change “Trimming and NativeAOT: All assemblies trimmed by default” only apply to projects with PublishAot true ?

  • 

    Michal Strehovsky August 10, 2022 0

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    It applies to both PublishTrimmed and PublishAot (PublishAot just turns on PublishTrimmed implicitly and it’s not possible to turn it off).

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  Marko Stupar August 9, 2022 · Edited 0

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  .net 7 preview 7

  System.Security.VerificationException: ‘Method System.Text.RegularExpressions.Symbolic.SymbolicRegexMatcher`1+FullNullabilityHandler[TSet].System.Text.RegularExpressions.Symbolic.SymbolicRegexMatcher.INullabilityHandler.IsNullableAt: type argument ‘TStateHandler’ violates the constraint of type parameter ‘TStateHandler’.’

  .net 7 preview 6

  Method System.Text.RegularExpressions.Symbolic.SymbolicRegexMatcher`1+FullNullabilityHandler[TSet].IsNullableAt: type argument ‘TStateHandler’ violates the constraint of type parameter ‘TStateHandler’.

  .net 7 preview 5
  ok

  • 

    Stephen Toub - MSFT August 9, 2022 0

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    Can you share a repro?

    • 

      Marko Stupar August 9, 2022 · Edited 0

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      pseudoCode:

      Type x = Type {FullName = “System.Text.RegularExpressions.Symbolic.SymbolicRegexMatcher`1+FullNullabilityHandler”, GenericTypeParameters{TSet}, GenericTypeArguments{}, IsGenericTypeDefinition = true};

      Type x2 = Type {Name = “INullabilityHandler”, FullName = null, DeclaringType = Type{FullName = “System.Text.RegularExpressions.Symbolic.SymbolicRegexMatcher`1”, IsGenericTypeDefinition = true} }

      x.GetInterfaceMap(x2);

    • 

      Marko Stupar August 9, 2022 0

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      realCode:

      using System.Reflection;
      
      namespace net7
      {
          internal static class Program
          {
              [STAThread]
              static void Main()
              {
                  Assembly a = Assembly.Load("System.Text.RegularExpressions");
                  Type x = a.GetType("System.Text.RegularExpressions.Symbolic.SymbolicRegexMatcher`1+FullNullabilityHandler");
                  Type x2 = x.GetInterface("INullabilityHandler");
      
                  
      
      
                  x.GetInterfaceMap(x2);
              }
          }
      }

    • 

      Stephen Toub - MSFT August 9, 2022 0

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      Thanks. I opened https://github.com/dotnet/runtime/issues/73658.

    • 

      Marko Stupar August 9, 2022 · Edited 0

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      framework recursive reflection pass and test, when it comes out new.

      comparing with previous versions, is it growing. (in natural speaking "pushing every button", "small code recursively pushes every button")

      i haven't expected that there would be any error, and first noticed it in preview 6. i thought it is normal because it is preview and it would be fixed in next version. in preview 7 here it is again, should i post about it...

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      framework recursive reflection pass and test, when it comes out new.

      comparing with previous versions, is it growing. (in natural speaking “pushing every button”, “small code recursively pushes every button”)

      i haven’t expected that there would be any error, and first noticed it in preview 6. i thought it is normal because it is preview and it would be fixed in next version. in preview 7 here it is again, should i post about it ? and i posted.

      when error occurred i was looking where the recursion went it. because of that i needed time to understand, by debugging, what it operated on and generate realCode.

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    • 

      Stephen Toub - MSFT August 9, 2022 · Edited 0

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      Thanks. Exception aside, why are you using private reflection to access these internal implementation details?