6.0.0

After 2 years of development, v6.0.0 is officially here!

This version focuses on five key milestones:

• Expanded Architecture Support: A new Platform abstraction enables support for more architectures, including ARM32 and ARM64. Furthermore, this version revamps the entire PE file building mechanism, and introduces TemplatedPEFileBuilder as a flexible foundation for building native Windows PEs and mixed-mode .NET modules.

• Multi-Assembly Processing: A single .NET assembly is rarely fully self-contained and typically references code in external assemblies (e.g., DLLs). This version introduces RuntimeContext, which mimics an AppDomain or AssemblyLoadContext. It is responsible for automating assembly resolution and shared metadata caching, and significantly improves .NET cross-binary processing.

• API Simplification: The API has undergone many Quality-of-Life improvements, removing many redundant interfaces and namespaces, adding more NRT annotations, and improving AOT trimming support. Furthermore, it is no longer required to manually import metadata as AsmResolver now auto-importing references at build time.

• Improved Portability: With the help of @MonoMod, we now support more build targets, including .NET Framework 3.5. We thereby extend compatibility to legacy environments like older versions of Unity/Mono.

• Performance Boosts: Next to RuntimeContext's shared caching model and more lazy evaluation, we now leverage Span<T>, source generators, and other modern .NET features in more places, delivering significantly faster PE processing with fewer allocations and lowering memory consumption across the board.

We've seen a huge uptick in the number of contributors, bug testers and new users over this period. A huge thank you to all of you! Without you this release wouldn't have been possible!

Migrating from v5.x

Migrating from v5.x requires addressing breaking changes. See the Migration Guide for more information.

Full Changelog

Changelog is relative to v5.5.1.

General Changes

12 changes

Improvements

• Remove System.Text.Json as a hard dependency for older .NET (FX) targets (#450, #538).
• Remove many redundant interfaces (e.g., IPEFile and IPEImage) (#445, #561, #562).
• Flatten many namespaces, drastically reducing the required using directives for typical use (#446, #560).
• Use EmptyErrorListener.Instance for reading input files by default (#472, #564).
• Add IInputFile::BaseAddress (a1af121)
• Add IReadOnlyList<T> explicitly to collection classes for better compatibility with lower .NET targets (62ed463)
• Add PatchContext::WriterBase (#653)

Performance

• Improve the internal mechanisms for lazy-initialization using source generated lazy properties, significantly reducing the number of allocations across the entire library (#683)
• Use built-in memory-mapped file APIs on newer .NET build targets (#619, thanks @teo-tsirpanis)
• Optimize BinaryStreamWriter for .NET 10+ targets (#695, thanks @Sergio0694).
• Add Utf8String::CreateUnsafe factory method which avoids cloning many small byte arrays (#709, thanks @Windows10CE)
• Let Utf8String implement ISpanFormattable and IUtf8SpanFormattable (#699, thanks @Sergio0694).

AsmResolver.PE.File

8 changes

Improvements

• Change PESection::Name to be of type Utf8String (#454).
• Add OptionalHeader::SetDataDirectory helper method (7b27c91).
• Add DataDirectory.CreateForSegment helper method (7b27c91).
• Add support for debug data to be read from EOF / overlay segments (#583, thanks @DaZombieKiller).
• Add BinaryStreamReader::ReadBytes(int32) (5863886)

Performance

• Add support for reading PE files from streams (#664, thanks @ds5678)

Bug Fixes

• Fix an issue where UTF8 strings were not concatenated properly (#650, thanks @ds5678)
• Fix an issue related to patched segments not being serialized properly to the final PE file (#653)

AsmResolver.PE

40 changes

Improvements

• Add Platform class (#643, #653)
• Add PEImage::ToPEFile
• Add EmptyDebugDataSegment (798a4ed)
• Exception data directory improvements:
  • Rename IExceptionDirectory::GetEntries to GetFunctions (#643)
  • Add IRuntimeFunction::UnwindInfo and add support for ARM RUNTIME_FUNCTION parsing (#643)
• .NET metadata directories improvements:
  • Add TargetRuntimeProber to detect the target runtime of a PE image without loading it as a full ModuleDefinition (#704).
  • Add MetadataDirectory::GetImpliedStreamSelection() (#704).
  • Metadata table model improvements:
    • Let IMetadataTable implement ISegment (9251f19)
    • Add Insert and TryGetRidByKey to MetadataTable (0acd8ca)
  • Add linear sweep blob enumerators for #Blob, #Guid, #Strings and #US streams (b7f67d0).
  • Add BlobStreamBuffer::GetBlobIndex for .NET 9+ targets (#680).
  • Add missing/newly introduced metadata flags:
    • Add missing EventAttributes.None (#676, thanks @Sergio0694)
    • Add missing AggressiveInlining, AggressiveOptimization and HasSecurityMitigations flags to MethodDefinition and MethodImplAttributes (bf80344).
    • Add missing TypeAttributes::WindowsRuntime (#710, thanks @Sergio0694).
    • Add new GenericParameterAttributes::AllowByRefLike attribute property (#623, thanks @ds5678)
  • • Add new MethodImplAttributes.Async to reflect .NET 10 runtime changes on async methods (#687, thanks @Windows10CE)

Performance

• Let all IMetadataRow structures implement IEquatable, avoiding lots of boxing and reflection calls (aaf4d6e)
• Add FastCilReassembler for allocationless patching of CIL method bodies (#672)

Bug Fixes

• Fix an issue where Win32 resources were inserted into a PE's root resource directory out-of-order, causing version info and icons to not be interpreted by Windows correctly (#552, #553).
• Fix an issue where the RSDS parser would incorrectly include a null terminator byte in the PDB path (#584, thanks @Windows10CE)
• Fix an issue where zero base relocation blocks were duplicated unnecessarily (fd9cbb5)
• Fix an issue where computing the offset range for a single metadata row would be incorrect (e1f3a9c)
• Fix an issue where some ReadyToRun metadata read from a file would not be assigned an offset/rva (490176a)
• Fix an issue where offsets in TLS data directories would not roundtrip properly (#706, #708).
• Fix an issue where relocation table entries would be duplicated or misaligned in some cases (#708).
• Fix an issue where debug data directories would not be read properly when files are loaded using MMIO (#718, thanks @js6pak).
• .NET metadata data directory parsing fixes:
  • Fix an issue where MetadataTable::TryGetRidByKey would not respect the sorted flag, causing some FieldRva to not select the appropriate ClassLayout row properly (#724, #728).
  • Fix a data race in caching mechanism of StringsStream and UserStringsStream (b1ded1f).
  • Fix an issue where offsets for metadata streams were not updated appropriately upon writing (008b91a)
  • Fix an issue where R2R x86_64 RuntimeFunctions sections could not be read correctly for non-Windows binaries (0660ccb)
  • Fix the interpretation of #Schema and #JTD metadata streams (#557, thanks @ElektroKill).
  • Fix an issue where EnC metadata streams are looked up using case insensitive name lookup (#557, thanks @ElektroKill).
  • Fix an issue where ENC metadata streams would not be selected appropriately when a #JTD stream is present (#632, thanks @ElektroKill)
  • Fix an issue where FieldRvaDataReader would not always select the correct metadata stream in various EnC situations (#724, #728).

AsmResolver.PE.Win32Resources

1 change

Improvements

• Rewrite IconResource into a more intuitive API that also supports language-specific icons and cursors (#565).

AsmResolver.DotNet

62 changes

Improvements

Assembly resolution improvements:

• Introduce RuntimeContexts, allowing for better multi-assembly processing.
• Remove all parameterless Resolve methods in favor of the new Resolve and TryResolve methods taking a RuntimeContext. Additionally, all properties and methods that may have implicitly required resolution will now take a RuntimeContext as well.
• Simplified and improved DotNetCorePathProvider, add MonoPathProvider and add NIX support (#657)
• Add various known corlib targets for .NET 9, 10, 11 and generic fallback support for future unsupported versions (#548, #645, #651, 8e11fef, #702, 55c847f, thanks @Sergio0694 and @ds5678).
• Add more default assembly resolvers: NullAssemblyResolver, PathAssemblyResolver and BundleAssemblyResolver (2fc1872, #721, thanks @js6pak)

Metadata builder improvements:

• Reference importing is now done automatically at build-time. In most cases there is no need for ReferenceImporter/ImportWith calls any more.
• Add more elaborate diagnostics to MemberNotImportedExceptions, including the location the unimported reference was detected (#626)
• Relax final nested type metadata table ordering restrictions to reflect runtime behavior (#545, #625)
• Add automatic sorting of CIL exception handlers on build (#707, thanks @Windows10CE

Metadata validation improvements:

• Add MethodDefinition::VerifyMetadata that checks for (accidental) inconsistencies in method metadata, including inconsistencies between static and HasThis and generic parameter counts (#642)
• Add validation of standalone signature contents in `CilInstructionCollection::Insert(CilO...

6.0.0-rc.1

This is the release candidate for 6.0.0, addressing some important regressions/shortcomings found in beta.6. Note that with this release the API design will be frozen, and only improvements/bug fixes will be implemented until full release.

Improvements

• Add NullAssemblyResolver and PathAssemblyResolver (#721, thanks @js6pak)
• Optimize CorLibTypeFactory.FromType to avoid many unnecessary string allocations (#717, thanks @wondercrash).
• Add ImportWith methods with more specific return types (#720, thanks @js6pak).
• Add support for IMemberDescriptor equality checks in SignatureComparer (#722, thanks @js6pak).
• Add missing NRT attributes for various TryResolve methods (e2bf223).
• Relax restrictions on input corlib for CorLibTypeFactory, making it easier to create one yourself (367968a)
• Remove redundant factory methods and remove params overloads in favor of using more explicit collection expressions for parameter types.

Bug Fixes

• Fix an issue where TargetRuntimeProber would crash with an ArgumentNullException when using AsmResolver in a .NET FX host (#723).
• Fix an issue where debug data directories would not be read properly when files are loaded using MMIO (#718, thanks @js6pak).
• Fix an issue where TypeSignature::IsAssignableTo and friends did not use the signature comparer of the provided RuntimeContext (0484a39)
• Fix an issue where MetadataTable::TryGetRidByKey would not respect the sorted flag, causing some FieldRva to not select the appropriate ClassLayout row properly (#724, #728).
• Fix an issue where FieldRvaDataReader would not always select the correct metadata stream in EnC situations (#724, #728).

6.0.0-beta.6

This release brings the long-needed metadata resolution revamp. The previous system often caused incorrect, duplicated, or silent failed assembly resolutions, which sometimes resulted in bad metadata to be emitted in output binaries. The new system makes RuntimeContext act more like an AppDomain/AssemblyLoadContext, centralizing assembly management and requiring all metadata resolution to go through it. Resolution is now also much more explicit, by always requiring a RuntimeContext instance. This ensures more reliable, predictable behavior when creating and processing .NET metadata.

Check out the updated documentation on RuntimeContexts on how to use the new APIs.

Full change log below:

New Features

• Breaking change: Revamp of metadata resolution system and RuntimeContexts (#704).
  • IAssemblyResolver is drastically simplified and is no longer responsible for caching anymore.
  • IMetadataResolver and friends are removed.
  • RuntimeContext construction is drastically simplified.
  • RuntimeContext is now responsible for resolving and maintaining assembly and metadata caches.
  • Add RuntimeContext::LoadAssembly methods to load assemblies into the context (similar to AssemblyDefinition::FromX, but using the context for reader parameters, cache and automatic wiring of dependencies).
  • Remove all Resolve methods in favor of a Resolve and TryResolve method taking a RuntimeContext. Additionally, all properties and methods that may have implicitly required resolution will now take a RuntimeContext as well.
  • SignatureComparer can now take a RuntimeContext in its constructor. When none is provided, the comparer will no longer try to resolve forwarder types and compare signatures as-is.
• Add TargetRuntimeProber to detect the target runtime of a PE image without loading it as a full ModuleDefinition (#704).
• Add MetadataDirectory::GetImpliedStreamSelection() (#704).
• Add read support for S_TRAMPOLINE and S_GTHREAD32 and S_LTHREAD32 PDB symbols (#711, thanks @dongle-the-gadget).

Improvements

• Breaking Change: Rename UnmanagedPEFileBuilder to TemplatedPEFileBuilder to more accurately reflect its behavior (727c554)
• Add .NET 11 support (#696, thanks @ds5678).
• Add support for (potentially unreleased) future target runtime versions not known yet to the current distribution of AsmResolver.DotNet (i.e., not explicitly added to KnownCorLibs) (#702, 55c847f).
• Optimize BinaryStreamWriter for .NET 10+ targets (#695, thanks @Sergio0694).
• Let Utf8String implement ISpanFormattable and IUtf8SpanFormattable (#699, thanks @Sergio0694).
• Add automatic sorting of CIL exception handlers on build (#707, thanks @Windows10CE).
• Add Utf8String::CreateUnsafe factory method (#709, thanks @Windows10CE)
• Add TypeAttributes::WindowsRuntime (#710, thanks @Sergio0694).
• Add ModuleDefinition::CreateConstructor overload taking CorLibTypeFactory (#712, thanks @Sergio0694).
• Add missing Class2, Structure2, Union2 and Interface2 PDB leaf record types (#714, thanks @ds5678).

Bug Fixes

• Fix an issue where auto-importing a type reference with a module definition as its scope would not turn into the declaring assembly (#697).
• Fix an issue where the custom attribute signature writer would incorrectly consider the context module of a type as the target module (#697).
• Fix an issue where associated metadata was duplicated even if the owner row was deduplicated (#697 ).
• Fix an issue where offsets in TLS data directories would not roundtrip properly (#706, #708).
• Fix an issue where relocation table entries would be duplicated or misaligned in some cases (#708).

6.0.0-beta.5

Version 6.0.0-beta.5 is mostly a performance upgrade that also comes with a few improvements to make AsmResolver .NET 10-ready, as well as a couple of bug fixes.

Full changelog below:

New Features

• Add FastCilReassembler for allocationless patching of CIL method bodies (#672)
• Add TypeAttributes::ExtendedLayout and TypeDefinition::IsExtendedLayout to reflect .NET 10 runtime changes to struct layout (dcc9162)
• Add MethodImplAttributes.Async and MethodDefinition::IsRuntimeAsync to reflect .NET 10 runtime changes on async methods (#687, thanks @Windows10CE)
• Add automatic importing of external type/field/method definitions (#689, thanks @Windows10CE)
• Add .NET 10 build targets (8e11fef)

Improvements

• Improve the internal mechanisms for lazy-initialization using source generated lazy properties, significantly reducing the number of allocations across the entire library (#683)
• Add lazy initialized SerializedCilMethodBody that avoids unnecessarily fully decoding a method body where possible (#672)
• Add allocation-less HasX properties, reducing memory footprint of roundtripping assemblies (#680)
• Add BlobStreamBuffer::GetBlobIndex for .NET 9+ targets (#680).
• Mark name parameter for FieldDefinition constructor nullable (#673, thanks @ds5678)
• Replace constructors of ExportedType to take in Utf8String instead of string (#675, thanks @Sergio0694)
• Remove redundant ModuleDefinition constructors taking in string (#674, thanks @ds5678)
• Add missing EventAttributes.None (#676, thanks @Sergio0694)
• Let GetOrCreateParameterDefinition insert newly generated parameter definitions at the index implied by its sequence (#677, thanks @ds5678)
• Add legacy runtime infos .NETCore and .NETPortable (#682, #684, thanks @ds5678)

Bug Fixes

• Fix an issue where type signatures were not always resolved correctly (f8ee34b)
• Fix a regression where ExpandMacros and OptimizeMacros would fail on some macro expanded instructions including ldc.i4 and ldarg (#678, #679, thanks @Windows10CE)
• Fix an issue where some type references with an assembly self-reference scope would re-resolve the assembly definition and thus not return the same type definition instance (8172ad5)

6.0.0-beta.4

It's been a while since the last beta.3 release, and the main reason for this has been that beta.3 saw many more testers actively trying out v6.0.0 and pushing it to its limits. Beta.4 addresses many bugs and shortcomings found during this period. Notable changes are ARM32 and ARM64 support, auto metadata references importing, and many DX improvements that make using AsmResolver even easier than before.

A huge thanks to all the testers and contributors for their commitment to the project!

See notes below for a full changelog:

New Features

• Add ARM64 platform support, including native thunk stub codegen and exception handlers (#643)
• Add ARM32 platform support, including native thunk stub codegen (#653)
• Add Generic platform for unsupported platforms to prevent unnecessary crashes on opening/saving these types of files (#653)
• Add Platform::GetOrGeneric factory method (#653)
• Add IRuntimeFunction::UnwindInfo (#643)
• Add new GenericParameterAttributes::AllowByRefLike attribute and corresponding GenericParameter::HasAllowByRefLike property (#623, thanks @ds5678)
• Add PatchContext::WriterBase (#653)
• Add MonoPathProvider (#657)
• Add support for dotnet path resolution in Nix stores (#657)
• Add support for reading PE files from streams (#664, thanks @ds5678)
• Add MethodDefinition::VerifyMetadata that checks for (accidental) inconsistencies in metadata, including inconsistencies between static and HasThis and generic parameter counts (#642)

Improvements

• Remove owner parameter from the constructor of CilMethodBody (#641)
• Remove requirement of importing type and member references (#655)
• Let CreateTypeReference and CreateMemberReference auto import the created members (#655)
• Split IMemberDescriptor::Module into ContextModule and DeclaringModule for references and definitions respectively (#655)
• Add build targets for legacy .NET Framework 4.6.2 and 4.7.2
• Rename IExceptionDirectory::GetEntries to GetFunctions (#643)
• Add CustomAttribute::Type shortcut property (#622, thanks @ds5678)
• Add support for creating new modules with a null corlib scope to create new corlib modules (#620, #621, thanks @ds5678)
• Use built-in memory-mapped file APIs on newer .NET build targets (#619, thanks @teo-tsirpanis)
• Relax final nested type metadata table ordering restrictions to reflect runtime behavior as opposed to ECMA-335 specification (#545, #625)
• Ensure a newly created <Module> type always has RID 1 (#625)
• Add more convenience factory methods to Constant (#627, thanks @ds5678)
• Add more elaborate diagnostics to MemberNotImportedExceptions, including the location the unimported reference was detected (#626)
• Respect new Field RVA alignment requirements specified in the latest ECMA-335 augmentations (#628, thanks @Windows10CE)
• Add MakeBoxedType extension method (#629, thanks @ds5678)
• Add HasCustomAttribute overloads accepting Utf8String (#633, thanks @Sergio0694)
• Resolve some Native AOT warnings (#631, thanks @Sergio0694)
• Add validation of standalone signature contents in CilInstructionCollection::Insert(CilOpCode, StandAloneSiganture) (#642)
• Add static/instance flag checks in constructor of MethodDefinition and an overload to suppress this (#642)
• Add .NET 10 known corlib references (#645, #651, thanks @Sergio0694 and @ds5678)
• Let IMethodDefOrRef inherit from ICustomAttributeType instead of the other way around to avoid verbose casts in user code (#658, thanks @Windows10CE)
• Simplified and improved DotNetCorePathProvider and friends (#657)
• Add HideBySig method flag to newly created static class constructors (#659, thanks @ds5678)
• Add better type coercion while comparing ITypeDescriptors using SignatureComparer (#656, thanks @Windows10CE)

Bug Fixes

• Fix an issue where types parsed from a Custom Attribute signature were not resolvable (61f9115)
• Fix various Custom Attribute type name parsing problems (#647, #648, thanks @Windows10CE)
• Fix an issue where ExportedTypes were not handled by MemberNameGenerator appropriately (ff455e9)
• Fix an issue where offsets for metadata streams were not updated appropriately upon writing (008b91a)
• Fix an issue in method and field accessibility tests in nested types (0942aba, thanks @ds5678)
• Fix an issue where ENC metadata streams would not be selected appropriately when a #JTD stream is present (#632, thanks @ElektroKill)
• Fix an issue where System.Enum itself would incorrectly be classified as a value type (#635. #636, thanks @AndrewSav)
• Fix an issue related to comparing forwarder types using SignatureComparer (#634, thanks @js6pak)
• Fix conflicting flag constants in MetadataBuilderFlags (#642)
• Fix an issue where UTF8 strings were not concatenated properly (#650, thanks @ds5678)
• Fix an issue related to patched segments not being serialized properly to the final PE file (#653)
• Fix an issue where unreachable exception handlers in a CIL method body would incorrectly still be included in max stack calculation (#652)
• Fix an issue related to nested types incorrectly being owned by both a ModuleDefinition and a TypeDefinition (#656, thanks @Windows10CE)
• Fix an issue where assemblies with a specific culture set would be resolved correctly but not returned to the caller (##668, thanks @Meivyn)

6.0.0-beta.3

This is a maintenance release. AsmResolver is closing in on a main release with most of the public API being stable. However, similar to 6.0.0-beta.2, this is still a pre-release and some of the public APIs are still subject to change.

Improvements

• Add IReadOnlyList<T> explicitly to collection classes for better compatibility with lower .NET targets (62ed463)
• Mark ManagedPEFileBuilder and UnmanagedPEFileBuilder's method body and field RVA data methods as virtual (166b541)
• Add PEReaderContext::Platform that can be reused throughout the PE parsing stage (0660ccb)
• Ensure Culture appears before PublicKeyToken in assembly full names to keep Mono happy (#614, thanks @ds5678)
• Rework type signature parsing in custom attribute blobs (#598, #616)
• Use built-in RuntimeTypeHandle::FromIntPtr of .NET 7+ for resolving type handles in dynamic methods when possible (#617, thanks @teo-tsirpanis)

Bug Fixes

• Fix an issue where parsed TypeSignatures in a Custom Attribute would not always have the correct IsValueType property set (#598, #616)
• Fix an issue where R2R x86_64 RuntimeFunctions sections could not be read correctly for non-Windows binaries (0660ccb)
• Fix an off-by-one error that would result in some binaries with large amounts of methods and custom attributes to throw BadImageFormatExceptions (#608, #609)
• Fix an issue where invalid coded indices in a metadata table would result in exceptions upon resolving of the (invalid) referenced metadata member (1e1f9b9)

6.0.0-beta.2

This is a maintenance release that fixes some shortcomings and addresses various regressions introduced by the refactors in 6.0.0-beta.1.

Similar to 6.0.0-beta.1, this is an unstable release and the public API are still subject to change.

Improvements

• Add more nullable attributes (#575, #604, thanks @ds5678)
• Add GenericParameter::Variance property (#578, thanks @ds5678)
• SentinelTypeSignature is now a singleton (#581, thanks @ds5678)
• Add Insert and TryGetRidByKey to MetadataTable (0acd8ca)
• Add support for debug data to be read from EOF / overlay segments (#583, thanks @DaZombieKiller).
• Add EmptyDebugDataSegment (798a4ed)
• Add BinaryStreamReader::ReadBytes(int32) (5863886)
• Let IMetadataTable implement ISegment (9251f19)
• Add linear sweep blob enumerators for #Blob, #Guid, #Strings and #US streams (b7f67d0).
• Let all IMetadataRow structures implement IEquatable (aaf4d6e)
• Ensure a type's namespace is always null or non-empty (#602, thanks @ds5678)
• Drastically increase the accuracy of IMemberDefinition::IsAccessibleFrom and add analogous CanAccessDefinition methods (71d345f)

Bug Fixes

• Fix an issue when cloning a method body using MemberCloner would not import calli operands properly (4a02161)
• Fix an issue where the RSDS parser would incorrectly include a null terminator byte in the PDB path (#584, thanks @Windows10CE)
• Fix an issue where export directories would be duplicated when using UnmanagedPEFileBuilder (3200229)
• Fix an issue where zero base relocation blocks were duplicated unnecessarily (fd9cbb5)
• Fix an issue where in some cases a non-empty import directory would be removed incorrectly if the UnmanagedPEFileBuilder was instructed to not trampoline the IAT (5f65621).
• Fix an issue where cloned properties and events were not included in the final ClonedMembers collection in MemberCloneResult (#592)
• Fix an issue where comparing two generic methods using SignatureComparer would result in a different conclusion depending on the order in which the two are passed onto the comparer (#595, thanks @ds5678).
• Fix an issue when computing the offset range for a single metadata row (e1f3a9c)
• Fix an issue where some ReadyToRun metadata read from a file would not be assigned an offset/rva (490176a)

6.0.0-beta.1

This marks the second major bump of AsmResolver since the rewrite. Note that this is still a pre-release and that last-minute breaking API changes may still be introduced before full release.

Summary

Version 6.0.0 of AsmResolver focuses on achieving three very important long-awaited milestones:

1. Unmanaged PE file building: A complete revamp of the underlying PE file building mechanism has finally allowed for a long-awaited UnmanagedPEFileBuilder: A robust yet flexible foundation for reconstructing fully native PE files as well as mixed-mode .NET modules. We are not quite there yet with integrating it into the AsmResolver.DotNet package, but it should pave the way for it as well as help with processing ReadyToRun- and NativeAOT-compiled files in the future. See the new documentation for details.

2. .NET Framework 3.5 support: Previously, AsmResolver targeted .NET standard 2.0, allowing developers to use a .NET Framework version as low as 4.6.1. While 4.8.1 is installed by default on modern Windows machines and we are approaching the release of .NET 9, many use-cases still require older versions of .NET (in particular, game-modding and dynamic code deobfuscation). With the awesome help of the people behind the @MonoMod project, we have been finally able to make AsmResolver 6.0.0 fully compatible with .NET Framework 3.5.

3. API simplification and improvements: The existing public API also has undergone many quality-of-life improvements to ensure a better developer experience. This includes removing many of the redundant interfaces, as well as flattening a lot of namespaces to reduce the number of using directives required for typical usecases of AsmResolver. Performance has also been improved a lot in various areas, partially thanks to the new concept of RuntimeContexts. And of course, many bug fixes have been squashed.

Important to note is that this release introduces breaking changes with respect to 5.x.x. In the following, the important changes are listed:

New Features

• Add UnmanagedPEFileBuilder, allowing for PEImages containing only native code or both native and managed .NET code to be built with little effort (#554).
• It is now much easier to customize existing PE file builders (or create your own) to get full control over the final PE file layout thanks to the new PEFileBuilder base class.
• Add .NET 3.5 support, using MonoMod.Backports (#536, #540, #544, #450, #439, with the help of @MonoMod and @Windows10CE).
• Add the concept of RuntimeContexts, allowing for .NET modules to be loaded under a specific .NET runtime or AppHost bundle context, which avoids many type resolution problems, drastically reduces memory footprint and also increases overall performance (#471, #537).
• Add PEImage::ToPEFile().
• Add TrampolineTableBuffer, allowing for IAT trampolines to be built easily.
• Add TypeMemoryLayout::IsReferenceOrContainsReferences flag, equivalent to RuntimeHelpers::IsReferenceOrContainsReferences<T> but determined statically (#530, #539).
• Add BundleAssemblyResolver (2fc1872)
• Add SetAccessorMethods to PropertyDefinition and EventDefinition (#555, thanks @ds5678).
• Add AggressiveInlining, AggressiveOptimization and HasSecurityMitigations flags to MethodDefinition and MethodImplAttributes (bf80344).
• Add IInputFile::BaseAddress (a1af121)

Improvements

• Remove many redundant interfaces (e.g., IPEFile and IPEImage). Developers are expected to use their immediate implementing class (i.e., PEFile and PEImage) (#445, #561, #562).
• Flatten many namespaces, drastically reducing the required using directives for typical AsmResolver usecases (#446, #560).
• Use EmptyErrorListener.Instance for reading input files by default (#472, #564).
• Remove System.Text.Json as a hard dependency requirement, making the library more portable for older .NET targets ( #450, #538).
• Add .NET 9 as a known corlib (#548, thanks @ds5678).
• Add correct interpretation of #Schema and #JTD metadata streams (#557, thanks @ElektroKill).
• Add FunctionPointerTypeSignature support for SignatureComparer::GetHashCode (#551, thanks @BadRyuner).
• Rewrite IconResource into a more intuitive API that also supports language-specific icons and cursors (#565).
• Let PESection::Name accept arbitrary UTF8 strings (#454).
• Add OptionalHeader::SetDataDirectory (7b27c91).
• Add SetDataDirectory.CreateForSegment (7b27c91.)

Bug Fixes

• Fix an issue where EnC metadata streams are looked up using case insensitive name lookup (#557, thanks @ElektroKill).
• Fix an issue where Win32 resources were inserted into a PE's root resource directory out-of-order, causing version info and icons to not be interpreted by Windows correctly (#552, #553).
• Fix a data race in caching mechanism of StringsStream and UserStringsStream (b1ded1f).
• Fix an issue related to reading and writing signed compressed integers for lower bounds in array type signatures (c7bc9f6).

Documentation

• Documentation on the new PE file building mechanism was added.
• The AsmResolver.PE.Win32Resource package now has its dedicated documentation section.

5.5.1

This is an incremental maintenance release that adds .NET 8.0 as an official target and fixes issues related to type signatures, CIL optimizations, as well as some rare edge cases in .NET metadata directory parsing.

New Features

• Add support for importing function pointer type signatures via reflection (#523, thanks @Windows10CE).
• Add BinaryStreamWriter::AlignRelative (af2e49d)
• Add .NET 8.0 target.

Bug Fixes

• Fix a couple issues regarding hash computation of generic instance and custom modifier type signatures in SignatureComparer (#512, thanks @rstarkov)
• Fix an issue where optimizing ldloca and ldarga opcodes would not shorten to their shorter variants (9ab4e94)
• Fix an issue where the same metadata members could be added twice to the exact same collection, resulting in ownership problems (#513)
• Fix an issue where .NET modules containing a metadata directory at an unaligned offset would read stream headers incorrectly (af2e49d).

5.5.0

This version brings rudimentary low-level .NET ReadyToRun (R2R) parsing and writing to AsmResolver, allowing you to locate and read native code of precompiled managed method bodies (see documentation). Additionally, basic Span<T> support was added to primitives like IDataSource and Utf8String for newer .NET runtime targets (netstandard 2.1 and above), and some new convenience APIs were added. Finally, some bugfixes were implemented, increasing general stability of the library.

New Features

• Add support for low level .NET ReadyToRun assembly parsing (#294, #495). See documentation.
• Add basic Span<T> support for IDataSources and Utf8String (#483, thanks @DaZombieKiller).
• Add option to suppress .NET resource data deduplication (#492).
• Add TypeDefinition::GetConstructor, MethodDefinition::CreateConstructor and similar (#480).
• Add ReferenceTable primitive segment class, representing structures like VTables that can be directly used as a writable ISegment.
• Add BinaryStreamReader::RemainingLength.
• Reduce allocations of null SegmentReferences.
• Add netstandard2.1 target.

Bug Fixes

• TypeReference::IsImportedInModule now correctly takes its resolution scope into account (#497).
• Type resolution now correctly first checks whether the resolution scope refers to the current assembly (7403692).
• TypeNameParser now correctly does not return fully imported types, but they can still be resolved using .Resolve() (#497).
• MemberCloner now correctly fixes cross-references to included System.Type arguments in Custom Attributes (#482, #493).
• Fixed an issue where .NET resource data with a malformed header would crash the parser (#492).
• Fixed an issue where ZeroesDataSource would clear out too much data in the buffer provided to ReadBytes (thanks @DaZombieKiller)
• Fixed an issue where BitList would incorrectly accept negative indices (#478).
• Fixed an issue where duplicated members would not be added even when preserving metadata tokens (#478).
• Fixed an issue where members with manually assigned tokens would not be saved correctly when assembly had no backing .NET directory (#478)
• Fixed a race condition in the caching mechanism of assembly resolution (61b6ddf)
• Fixed a race condition in the caching mechanism of input file services (61b6ddf)
• Fixed an issue where string operands in IL pretty printed instructions were not escaped properly (6e039b9)

Minor Breaking Changes

• Remove TlsCallbackCollection, replaced with ReferenceTable.
• TlsDirectory::CallbackFunctions is now of type ReferenceTable.
• IDotNetDirectory::ManagedNativeHeader is now of the more specific segment type IManagedNativeHeader.