Optional single-child slots return T? with a real null instead of a role
null-object, taking the C# grammar as the oracle for which slots are optional.
The generator emits the property type as T? and matches it with MatchOptional,
and consumers move from .IsNull to is null / ?.. This covers the optional
statement, member, try-catch, creation-initializer and pattern slots and the
optional NameSlot tokens. A few slots the grammar marks required but the
decompiler legitimately leaves empty (the implicit-element-access target, an
implicitly-typed lambda parameter's type) are flipped to nullable as well.
Assisted-by: Claude:claude-opus-4-8:Claude Code
A [NameSlot("role")] partial string property makes the generator own the
backing Identifier token slot, the string accessor, and the match term, so a
convenience name string and its hand-written token slot collapse to a single
declaration. A nullOnEmpty option stores a null token for an empty name, used
where the output visitor keys off an absent token. Apply it across every
name-token node.
Assisted-by: Claude:claude-opus-4-8:Claude Code
NodeType was NRefactory's coarse node category, but only three reads remained
here: two checks now expressed as "is not Trivia" and one debug assert for the
pattern category. Remove the enum, the abstract property, every per-node
override, and the generator's emission, preserving the pattern-placeholder case
through an IPatternPlaceholder marker interface the output-visitor assert
checks. Also remove the unused PrimitiveExpression.AdvanceLocation helper.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Delete source-fidelity state the decompiler never reads, since it generates
the AST and never parses: SyntaxTree.FileName/ConditionalSymbols/TopExpression,
Comment.StartsLine/IsDocumentation, the preprocessor line/file fields, and a
computed ComposedType flag. Hoist the duplicated start/end location storage
into the shared Trivia base, and drop the redundant per-instance Location field
on single-token leaf nodes in favor of the base's print-time location.
Generate DoMatch for the last nodes (Comment, SyntaxTree, the using and
namespace declarations, Identifier).
Assisted-by: Claude:claude-opus-4-8:Claude Code
Generate DoMatch across the remaining expression, statement, type-member,
type-reference and general-scope nodes, including the inherited
EntityDeclaration name/return-type/attribute match, and stop generating it for
abstract base nodes. Matching every structural member fixes real
under-matching bugs (PointerReferenceExpression ignored its Target;
ExtensionDeclaration matched anything) while computed or derived members are
excluded from matching. PrimitiveExpression and PreProcessorDirective stay
hand-written by design. Pretty output is byte-identical.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The grammar-production doc comments were transcribed in ANTLR style and
often copied the C# spec verbatim, including sub-rules the AST does not
model. Rewrite them as W3C EBNF (::=, ?, *, +), unroll sub-productions
that are not themselves AST nodes (e.g. anonymous_function_modifier ->
'async'), and shape each production to the node's actual members. Render
top-level alternations of node productions as multi-line <code> blocks;
keep operator and keyword token lists inline.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Replace the hand-written DoMatch overrides on the expression nodes with
generated ones. The generator matches every real child and structural member,
so several matchers become stricter than the hand-written versions that
under-matched (for example a previously-skipped child or an ignored flag),
while Pretty output is unaffected. Convenience-string identifier slots are
excluded so the name string is matched once rather than also via its token.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Each concrete syntax node now carries, in an XML-doc <remarks> block, the
matching production from the C# language specification grammar (ECMA/Microsoft,
ANTLR notation), quoted verbatim. Aggregate nodes (e.g. BinaryOperatorExpression,
ComposedType, TypeDeclaration) list every production they span; lexical/trivia
nodes (Comment, the preprocessor directives, Identifier) cite the lexical rule.
Nodes with no spec production -- ErrorExpression, UndocumentedExpression,
InvocationAstType, TypeReferenceExpression, NamedExpression, DocumentationReference,
and the C# 14 ExtensionDeclaration -- carry a hand-written EBNF plus a note
explaining why no official production exists.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Comments and preprocessor directives were positional children interleaved
into the child list, and punctuation, keywords and operators were token-node
children. Add a leading/trailing trivia side-channel for comments and
directives, emit it from the output visitor, and re-home every comment
receiver onto it (including inside-block comments as comment-only empty
statements and undecodable attribute arguments as an ErrorExpression). With
locations and sequence points no longer sourced from token nodes, stop
reconstructing them on the locations path and delete CSharpTokenNode,
CSharpModifierToken and InsertSpecialsDecorator. The AST no longer carries
token children or positional comments; output is byte-identical.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Each child of a C# AST node is declared as a [Slot] partial property, and the
source generator emits the accessor bodies and an ordered slot schema
(SlotCount/GetSlotRole/IsCollectionSlot) from them. Generating the schema
keeps slot order from being mis-stated by hand and lets a DEBUG invariant
check declared slot order against document order on every decompile. The node
hierarchy is converted family by family; the EntityDeclaration leaves flatten
their inherited Attributes/ReturnType/NameToken into each leaf's ordered slot
set. Storage stays the NRefactory linked list at this stage, so only the
declaration model changes and output is unchanged.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The generator emits the IAstVisitor interface, the AcceptVisitor overloads,
and the null-node and pattern-placeholder nodes from [DecompilerAstNode]
declarations, so drop the hand-written equivalents across the C# AST: per-node
AcceptVisitor/DoMatch, the #region Null / #region PatternPlaceholder blocks,
IAstVisitor.cs, and now-dead usings. Also adds AccessorKind and moves
IdentifierExpressionBackreference into the PatternMatching folder.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Introduce a Roslyn source generator that emits the visitor boilerplate for
the C# AST from [DecompilerAstNode]-tagged node declarations: the
IAstVisitor interface, the AcceptVisitor overloads, the pattern-placeholder
nodes, and the initial DoMatch support. AccessorKind lets an accessor's
keyword be chosen independently of its role, an early step toward shedding
the NRefactory role model.
The C# AST inherited NRefactory's freezable model (IFreezable, Freeze,
IsFrozen, a frozen flag bit, and ThrowIfFrozen guards on every mutator),
but the decompiler never uses it: nothing calls Freeze(), not even the
generated null-node singletons, so every IsFrozen guard only ever
evaluated false. The decompiler is single-threaded and never shares or
freezes nodes. Remove the whole apparatus as preparation for the
slot-based AST rewrite, which has no place for it. Roles are untouched
here, so the flags word keeps its role index; only the freed frozen bit
goes away.
This initial commit only handles the trivial case where an Index or Range object is constructed.
The TODO portions of the test case show there are plenty of cases where where the C# compiler emits more complex code patterns that will require ILAst transforms.
Siegfried Pammer
Peter Crabtree
Daniel Grunwald
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