Major Changes of Note

• ILSpy 6.0 sports a multi-tab docking interface
• ILSpy 6.0 comes with a new Metadata Explorer
• ILSpy 6.0 has new icons for high-DPI support
• ILSpy 6.0 requires at least .NET 4.7.2 (v5.0 required .NET 4.6.2)

New Language Features

• C# 8.0: Indexing and Slices (Ranges)
• C# 7.0: Changes to syntactic disambiguation of generic identifiers
• C# 7.3 pattern-based fixed statement
• C# 8.0 Default Interface Methods
• C# 8.0 Async streams (currently not covering await foreach)
• C# 8.0 await using
• C# 8.0 Readonly members
• Decompile calli instructions using C# 9.0 function pointer syntax
• Improved support for Unsafe intrinsics
• Support for generic and static local functions

UI Improvements

• Docking and multi tab support (see #1725 and #1801)
• Metadata Explorer (see https://github.com/icsharpcode/ILSpy/wiki/Metadata-Explorer)
• Assembly list dropdown in toolbar, enhanced assembly list management
• Show target frameworks next to the assembly version in the tree-view
• Using the middle mouse button to click on tree nodes and links will open the decompilation result in a new tab.
• "Select PDB" context menu: allows to change the PDB file resolved by ILSpy or pick one from a different location
• Added a "Debug Metadata Explorer" node for portable PDBs
• Use XAML for icons (high DPI)
• New icons (based on VS 2017 icon pack) (#1704 thanks to @Rpinski)
• RichText Tooltips (#1654)
• Add "Open with ILSpy" entry to the Windows Explorer context menu on exe and dll files (via Options/Misc)
• Empty metadata tables can now be hidden from the tree view
• Folding for XAML output (thanks to @jogibear9988)
• Add "Reset to defaults" in Options dialog
• Dynamic assembly list generation for target framework

Improvements & Bugfixes

• Project export: Added an option to allow SDK-style format for project files. (#2031 by @dymanoid)
• Solution and project decompilation: Add missing ProjectTypeGuids
• Add search features (thanks to @miloush and @sailro)
• #1498: Remove Fusion API usage: Use standard file enumeration instead. This should enable us to use the GAC even with restricted access, as only the LIST permission is required.
• Fix DotNetCorePathFinder to properly support netstandard2.1
• Fix multi-module support
• Updated links to MS Docs (#2030 by @AustinWise)
• Improve ReduceNestingTransform by considering nested containers (#1880 by @Chicken-Bones)
• Analyzers: Added "Implements interface"-Analyzer (#2028 by @dymanoid)
• Analyzer follow type forwarders (#1846 by @yyjdelete)
• The decompiler now supports Scalar Replacement Of Aggregates, which by default only works on display-classes and display-structs. There is an option to make it affect all instances and uses of plain types containing fields only. NOTE: It is still in preview stage. You can activate it when using a debug build.
• Added support for null-propagation on unconstrained generic expressions
• Added support for [module: NullablePublicOnly]
• Enhanced assembly resolution to distinguish target frameworks and use the correct references in case there are multiple versions of framework assemblies loaded.
• Better decompilation of local functions, pinned regions and display-classes
• Disassembler: actually make use of the cancellation token
• Support VB Select Case on string
• Display System.Void as struct (#1835 by @yyjdelete)
• Properly decompile auto events with tuples
• Do not change accessibility of non-transformed local functions
• Improve drag&drop support (#1860)
• Fix bug in stackalloc initializer detection involving Span<decimal> (see #1855 by @yyjdelete)
• Added struct constructor initializer pattern
• DotNetCorePathFinder: Various bug fixes when working with .net core assemblies
• Transform post-increment on float/double (#1769 thanks to @Chicken-Bones)
• Fix extra minus sign when formatting -0 on .NET Core 3.0 (#1790 thanks to @Chicken-Bones)
• Fix sealed modifier on interface methods with no body (#1792 thanks to @Chicken-Bones)
• Fix NullReferenceException when foreach decompilation is turned off (#1754 thanks to @davidwengier)
• Fixed performance problem when using an assembly from a MemoryStream (#1763 thanks to @yyjdelete)

Ready2Run (R2R)

• Ready2Run (by @cshung see https://github.com/icsharpcode/ILSpy/wiki/ILSpy.ReadyToRun)
• IL/IL with C#/ReadyToRun: Add metadata token hyperlinks to type, field, property and event declarations.
• IL/IL with C#/ReadyToRun: Add rich-text tooltips
• ReadyToRun: Optional output of UnwindInfo (#2043 by @edkazcarlson)
• ReadyToRun: Using import cell name to describe callees (#1991 by @cshung)
• ReadyToRun: Decorate the ready to run disassembly with DebugInfoBounds (#1987 by @cshung)

PDB Generation

• Improved sequence points of try-catch statements
• Improved generation of sequence points (#1967 by @jacdavis)
• PDB generation: Use correct sequence points in LINQ expressions and many smallish bug fixes

dotnet ilspycmd Tool

• New option: usepdb (for improved variable naming)
• Breaking change: option debuginfo renamed to genpdb
• #1740: Add LanguageVersion, RemoveDeadCode and RemoveDeadStores switches

ILSpy pwsh cmdlets

• Show a progress bar during decompilation