tweak in assembly equality comparer

[lafar6502]

Sometimes I got strange 'An item with the same key has already been added' from the MemoizedFunction, but this shouldn't be possible by looking at the Invoke code. I suspected this happens for dynamically generated assemblies (because I have seen this many times when compiling some boo-based dsl scripts) and by heuristics concluded that there might be a problem with equality comparer used with memoized function. Sorry, no definite test case as it was a 'heisenbug' almost impossible to reproduce reliably. Modified the assemblyequalitycomparer class, the change should not break anything - just replaced the hashcode generating method.

[lafar6502]

Stack trace example:

BCE0055: Boo.Lang.Compiler.CompilerError: Internal compiler error: An item with the same key has already been added.. ---> System.ArgumentException: An item with the same key has already been added.
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at Boo.Lang.Compiler.Util.MemoizedFunction`2.Invoke(TArg arg)
   at Boo.Lang.Compiler.TypeSystem.Reflection.AssemblyReference.Map(Type type)
   at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionTypeSystemProvider.Map(Type type)
   at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionNamespace.AddModule(Type type)
   at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionNamespace.Add(Type type)
   at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionNamespaceBuilder.CatalogPublicTypes(IEnumerable`1 types)
   at Boo.Lang.Compiler.TypeSystem.Reflection.ReflectionNamespaceBuilder.Build()
   at Boo.Lang.Compiler.TypeSystem.Reflection.AssemblyReference.CreateRootNamespace()
   at Boo.Lang.Compiler.TypeSystem.Reflection.AssemblyReference.get_RootNamespace()
   at Boo.Lang.Compiler.TypeSystem.Core.GlobalNamespace.<RootNamespaces>d__0.MoveNext()
   at Boo.Lang.Compiler.TypeSystem.Core.Namespaces.ResolveCoalescingNamespaces(INamespace parent, IEnumerable`1 namespacesToResolveAgainst, String name, EntityType typesToConsider, ICollection`1 resultingSet)
   at Boo.Lang.Compiler.TypeSystem.Core.GlobalNamespace.Resolve(ICollection`1 resultingSet, String name, EntityType typesToConsider)
   at Boo.Lang.Compiler.TypeSystem.Core.Namespaces.ResolveCoalescingNamespaces(INamespace parent, INamespace namespaceToResolveAgainst, String name, EntityType typesToConsider, ICollection`1 resultingSet)
   at Boo.Lang.Compiler.TypeSystem.Services.NameResolutionService.Resolve(ICollection`1 targetList, String name, EntityType flags)
   at Boo.Lang.Compiler.TypeSystem.Services.NameResolutionService.ResolveImpl(String name, EntityType flags)
   at Boo.Lang.Compiler.Util.MemoizedFunction`3.Invoke(T1 arg1, T2 arg2)
   at Boo.Lang.Compiler.TypeSystem.Services.NameResolutionService.Resolve(String name, EntityType flags)
   at Boo.Lang.Compiler.TypeSystem.Services.NameResolutionService.ResolveQualifiedName(String name, EntityType flags)
   at Boo.Lang.Compiler.TypeSystem.Services.NameResolutionService.ResolveQualifiedName(String name)
   at Boo.Lang.Compiler.Steps.MacroProcessing.MacroExpander.ResolvePreferringInternalMacros(String macroTypeName)
   at Boo.Lang.Compiler.Steps.MacroProcessing.MacroExpander.ResolveMacroName(MacroStatement node)
   at Boo.Lang.Compiler.Steps.MacroProcessing.MacroExpander.OnMacroStatement(MacroStatement node)
   at Boo.Lang.Compiler.Ast.MacroStatement.Accept(IAstVisitor visitor)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.OnNode(Node node)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.VisitNode(Node node)
   --- End of inner exception stack trace ---
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.OnError(Node node, Exception error)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.VisitNode(Node node)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.Visit[T](NodeCollection`1 collection)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.OnBlock(Block node)
   at Boo.Lang.Compiler.Ast.Block.Accept(IAstVisitor visitor)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.OnNode(Node node)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.VisitNode(Node node)
   at Boo.Lang.Compiler.Ast.DepthFirstTransformer.OnMethod(Method node)
   at Boo.Lang.Compiler.Ast.Method.Accept(IAstVisitor visitor)

[drslump]

@masonwheeler Does this look right to you? Shall we merge it?

[masonwheeler]

Looks good to me. If we want to hash assemblies, it's better to hash the assembly objects themselves than their names, especially if the current system is causing collisions.

[drslump]

thanks @lafar6502 and @masonwheeler!