Backing-field references inside a property's own get/set/init accessors
are emitted as the `field` keyword at IL-to-AST translation time
(ExpressionBuilder.ConvertField), so arbitrary accessor bodies become
expressible and no separate rewrite pass is needed. Compiler-generated
trivial accessors then collapse individually to `get;`/`set;`, which
also handles mixed shapes like `{ get; set { ... field ... } }`; the
backing-field declaration is removed with its remaining attributes
re-hosted as `field:` sections, and constructor stores become property
initializers (or property assignments, for setter-less properties).
Implicit zero-stores that auto-default struct constructors emit for
unassigned backing fields are dropped rather than lifted.
Recognition stays AST/metadata-based rather than mirroring the ILAst
analysis used for automatic events: events must prove compiler-generated
bodies before discarding them, while the field keyword discards nothing,
so name association plus the accessor context is sufficient.
Below C# 14 (or with the new FieldKeyword setting off), the field
declaration survives under its metadata name, so the UI keeps showing
the truth; EscapeInvalidIdentifiers - the transform the compilable-output
flows (project export, VS, tests) already add - now maps
`<P>k__BackingField` to the readable `P__BackingField` instead of the
generic character escape. A genuine field literally named "field" is
qualified as `this.field` inside accessors, and locals are not named
"field" there, since C# 14 rebinds the bare identifier. Bodiless
accessors mixed into multi-line properties get their own line in the
output.
The fixture covering the feature surface lands with the implementation rather
than as a separate xfailed commit. It is excluded from the test-assembly
compilation because its nullable annotations would trip warnings-as-errors
there.
Assisted-by: Claude:claude-fable-5:Claude Code
Widening the compiler matrix answers the open review question on the
Issue3230 fixture guard empirically: a class naming its own nested
interface in its base list is a Roslyn-era relaxation. The legacy csc
rejects every such shape with CS0146 (circular base class dependency,
it never reaches the accessibility check), mcs 2.6.4 rejects them with
CS0122/CS0146, and mcs 5.23 accepts them all, rejects naming a base
class's protected nested interface with the same CS0122 as Roslyn, and
emits the same transitive InterfaceImpl metadata. The fixtures are
therefore gated to ROSLYN || MCS5, which exercises the base-list filter
on mcs-generated metadata as well. The pre-existing class C needs
MCS2-specific expected output because mcs 2.6.4 reorders interface-impl
rows and explicit implementations in metadata.
Assisted-by: Claude:claude-fable-5:Claude Code
Covers ref structs implementing interfaces (implicit, explicit, and
default-interface-method reimplementation, which CS9245 forces on every
ref struct implementer), the allows ref struct anti-constraint on
methods, classes, interfaces, delegates, local functions, iterators,
async methods, and capturing local functions, constraint combinations
(interface, IDisposable with using, unmanaged, struct, new()),
interface members invoked through a constrained T (instance, static
abstract factory, and default interface methods, which are callable
through T because implementers must always override them), scoped/ref/
in/out parameters of T, and call sites instantiating with Span/
ReadOnlySpan type arguments.
The test is green in all four Roslyn 4.14/latest debug/opt configs: the
decompiler already round-trips the gpAcceptByRefLike flag into
"allows ref struct" clauses and re-emits ref struct interface
implementations correctly. One cosmetic quirk is pinned as-is: calls
whose type arguments are ref structs are printed with explicit type
arguments and a declaring-type qualifier even within the declaring
class, because type-argument inference validation does not accept ref
struct type arguments; the output remains compilable and semantically
identical.
Assisted-by: Claude:claude-fable-5:Claude Code
Override constraints are normally inherited and omitted, but nullable type
parameters still require class or default to distinguish annotations from
Nullable<T>. Derive that legal discriminator from the method metadata.
Assisted-by: Copilot:gpt-5.6-sol:GitHub Copilot CLI
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 86d2918e-5a24-48b4-9a86-41d331ec3720
The syntactic accessor-body patterns in PatternStatementTransform sit
downstream of every settings-dependent transform, so each new compiler
shape or settings combination silently broke recognition: with
AggressiveInlining enabled, static events inline the Delegate.Combine
call into CompareExchange positionally, which none of the four patterns
matched, while call sites were still rewritten to the event name from
metadata alone - producing uncompilable output (CS0079).
Recognition now happens in DoDecompile(IEvent) by structurally matching
the ILAst of the accessors, decompiled with a fixed set of settings the
same way RecordDecompiler analyzes method bodies. This makes detection
independent of the user-visible settings by construction. Events that
are not recognized fall back to the classic path unchanged, including
the existing AST patterns.
mcs 2.x compiles the accessors as a compound assignment, evaluating
'this' once via IL 'dup'; the simple-combine matcher accepts that
stack-slot alias.
Assisted-by: Claude:claude-fable-5:Claude Code
Roslyn caches a ReadOnlySpan<T> created from an array literal in a
<PrivateImplementationDetails> field on target frameworks without
RuntimeHelpers.CreateSpan (e.g. .NET Framework / netstandard2.0 + System.Memory):
object obj = <PrivateImplementationDetails>.cache;
if (obj == null) {
obj = new char[] { '\r', '\n' };
<PrivateImplementationDetails>.cache = (char[])obj;
}
... new ReadOnlySpan<char>((char[])obj) ...
The decompiled output referenced the compiler-synthesized
<PrivateImplementationDetails> type, whose escaped name is not expressible in C#
and is never declared, so the output failed to recompile (CS0400).
The modern RuntimeHelpers.CreateSpan form was already handled
(TransformRuntimeHelpersCreateSpanInitialization); this adds the analogous
handling for the legacy lazy-cache form, mirroring CachedDelegateInitialization
(which collapses the same lazy-static-field cache for anonymous-method delegates).
Once the cache is collapsed, the existing array-initializer transforms recover
the array literal, so the <PrivateImplementationDetails> reference disappears.
Test: ILPretty/CachedReadOnlySpanInitialization.
Added Issue3877 test to PrettyTestRunner and new test case source to verify dictionary initialization with negative capacity. Updated SwitchOnStringTransform to skip processing when a negative dictionary capacity is detected.
Awaiting a dynamic value lowers GetAwaiter/IsCompleted/GetResult to
dynamic callsites, which async decompilation could not recognize:
await detection ran before DynamicCallSiteTransform, so the await was
emitted as a raw state machine (or crashed in AnalyzeAwaitBlock, #1388).
AnalyzeStateMachine now collapses the awaiter callsites per block, folds
the runtime ICriticalNotifyCompletion branch the compiler emits for an
awaiter not statically known to implement it into the canonical single
call, and re-joins the branch chains the collapse leaves so each dynamic
await sits in one block. DetectAwaitPattern matches the dynamic
GetAwaiter/IsCompleted/GetResult shape and emits `await expr`; a
synthesized dynamic GetResult method gives the await and its local the
dynamic type. DynamicCallSiteTransform also follows callsite targets
spilled into state-machine locals, so an awaited value flowing into a
dynamic callsite (e.g. d.Result = await ..., #1928) decompiles too.
Assisted-by: Claude:claude-fable-5:Claude Code
Generic co-/contravariance had no test coverage at all: no out/in
variance modifier on any interface or delegate declaration and no
variant reference conversion appeared anywhere in the test suite.
The new fixture pins declarations (including a constrained covariant
interface and an explicit implementation of a variant interface) and
conversion shapes that must not produce explicit casts.
Assisted-by: Claude:claude-fable-5:Claude Code
Compilation uses the .NET builds of the Roslyn toolsets (tasks/netcore*,
bincore csc.dll/vbc.dll launched through the dotnet host). ilasm/ildasm
options use the '-' prefix, which all platforms accept. The dotnet-hosted
compilers have no implicit references or SDK path: net40 compiles pass
mscorlib explicitly, and vbc gets -sdkpath, _MYTYPE=Empty and
-vbruntime:Microsoft.VisualBasic.Core.dll (the facade in the ref packs is
not followed for runtime helpers). The TestRunner gets a self-contained
build for the host platform.
Configurations depending on Windows-only tools or runtimes (legacy
csc/vbc, Roslyn 1.x/2.x, mcs, Force32Bit, executing net40 binaries) are
filtered from the matrix off-Windows via Tester.SupportedOnCurrentPlatform
or gated with [Platform("Win")]. PdbGen comparisons normalize document
name separators, and Correctness/Async uses Console.IsInputRedirected
instead of the Windows-only Console.CapsLock.
Assisted-by: Claude:claude-fable-5:Claude Code
* Fix anonymous-type lambda early-return emitting unresolvable cast
When a lambda's inferred return type contains an anonymous type and one
branch returns null, the decompiler emitted an explicit cast such as
`return (IEnumerable<<>f__AnonymousType0<int>>)null;`, which is invalid C#.
Skip the cast in IsPossibleLossOfTypeInformation for null literals whenever
the expected type contains an anonymous type:
null is implicitly convertible to any reference type, so no cast is needed,
and the anonymous type has no nameable form to cast to anyway.
Fixes#3751
Various improvements regarding primary constructor decompilation, including:
- introduce `HasPrimaryConstructor` property in the AST, as there is a difference between no primary constructor and a parameterless primary constructor
- improved support for inherited records and forwarded ctor calls
- exclude non-public fields and properties in IsPrintedMember
- introduce an option to always make the decompiler emit primary constructors, when possible
* Parenthesize interpolations containing global::
* Improvements:
* Cleaner output
* More unit testing
* More efficient tree search
* Implement revisions
* Update Lambda1 to be invariant
* Visit descendents before deciding whether or not to parenthesize an interpolation expression
* Rename local function
* Remove branch for conditional expressions
* Handle Lambda expressions without a block body
* Check for parenthesized expressions
* `NET60` instead of `!NET40`
Siegfried Pammer
Sebastien Lebreton
ds5678
Jakob Hellermann
Maximilian Schmöcker
Jan Jones
Christoph Wille
Daniel Grunwald
ElektroKill