internal error on trait functions taking multiple arguments of trait type parameter

[erniecohen]

Dafny version

nightly 4/25/24

Code to produce this issue

newtype V = bv64 
trait Op<T> {
    //function op(t:T):T // no problem with this
    function op2(t0:T,t1:T):T // this triggers the problem
}

Command to run and resulting output

vscode

What happened?

Dafny encountered an internal error. Please report it at https://github.com/dafny-lang/dafny/issues.
System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Dafny.ModuleResolver.AddToInheritedMembers(TopLevelDeclWithMembers cl, TopLevelDeclWithMembers baseOrParentTypeDecl, Dictionary2 inheritedMembers, List1 membersWithErrors)
at Microsoft.Dafny.ModuleResolver.RegisterInheritedMembers(TopLevelDeclWithMembers cl, DPreType basePreType)
at Microsoft.Dafny.PreTypeResolver.ResolvePreTypeSignature(Declaration d, PreTypeInferenceModuleState preTypeInferenceModuleState, ModuleResolver resolver)
at Microsoft.Dafny.PreTypeResolver.ResolveDeclarations(List1 declarations, ModuleResolver resolver, Boolean firstPhaseOnly) at Microsoft.Dafny.ModuleResolver.ResolveTopLevelDecls_Core(List1 declarations, Graph1 datatypeDependencies, Graph1 codatatypeDependencies, String moduleDescription, Boolean isAnExport)
at Microsoft.Dafny.ModuleDefinition.Resolve(ModuleSignature sig, ModuleResolver resolver, String exportSetName)
at Microsoft.Dafny.LiteralModuleDecl.Resolve(ModuleResolver resolver, CompilationData compilation)
at Microsoft.Dafny.ModuleResolver.ResolveModuleDeclaration(CompilationData compilation, ModuleDecl decl)
at Microsoft.Dafny.ProgramResolver.ResolveModuleDeclaration(CompilationData compilation, ModuleDecl decl)
at Microsoft.Dafny.LanguageServer.Language.CachingResolver.ResolveModuleDeclaration(CompilationData compilation, ModuleDecl decl)
at Microsoft.Dafny.ProgramResolver.Resolve(CancellationToken cancellationToken)
at Microsoft.Dafny.LanguageServer.Language.CachingResolver.<>n__0(CancellationToken cancellationToken)
at Microsoft.Dafny.LanguageServer.Language.CachingResolver.<>c__DisplayClass5_0.b__0()
at Microsoft.Dafny.LanguageServer.Language.CacheExtensions.ProfileAndPruneCache[T,Key,Value](PruneIfNotUsedSinceLastPruneCache2 cache, Func1 useCache, TelemetryPublisherBase telemetryPublisher, String programName, String activity)
at Microsoft.Dafny.LanguageServer.Language.CachingResolver.Resolve(CancellationToken cancellationToken)
at Microsoft.Dafny.LanguageServer.Language.Symbols.DafnyLangSymbolResolver.RunDafnyResolver(Compilation compilation, Program program, CancellationToken cancellationToken)
at Microsoft.Dafny.LanguageServer.Language.Symbols.DafnyLangSymbolResolver.ResolveSymbols(Compilation compilation, Program program, CancellationToken cancellationToken)
at Microsoft.Dafny.TextDocumentLoader.ResolveInternal(Compilation compilation, Program program, CancellationToken cancellationToken)
at Microsoft.Dafny.TextDocumentLoader.<>c__DisplayClass5_0.<b__0>d.MoveNext()
--- End of stack trace from previous location ---
at Microsoft.Dafny.TextDocumentLoader.ResolveAsync(Compilation compilation, Program program, CancellationToken cancellationToken)
at Microsoft.Dafny.Compilation.ResolveAsync()

What type of operating system are you experiencing the problem on?

Mac

[erniecohen]

I assume this is a temporary breakage, but this means a regression test should probably be added.

[keyboardDrummer]

I assume this is a temporary breakage, but this means a regression test should probably be added.

Definitely. These reports are useful. We'll try to resolve them ASAP.