Completes the nullable migration for ICSharpCode.Decompiler/CSharp/Syntax: every
hand-written file now carries #nullable enable. The pattern-matching API
(INode/Pattern/PatternExtensions DoMatch/Match/IsMatch) takes a nullable 'other',
since matching legitimately compares a pattern against a missing child. Members
that genuinely return or accept null are annotated to match (AttributeSection's
target token, IAnnotatable.Annotation<T>, Statement/Expression.ReplaceWith,
SyntaxExtensions.GetNextStatement), and a latent null dereference in
Backreference.DoMatch is fixed.
Assisted-by: Claude:claude-opus-4-8:Claude Code
AstNode.Children and the visitors' VisitChildren walked children via
FirstChild/NextSibling, an O(slots) index rescan per step. The generator now
emits GetChildNodes, which materializes the children in slot order in one pass
(O(children)); Children and VisitChildren iterate that. The snapshot makes the
walk tolerant of the visitor removing or replacing the current child (the
mutation pattern the old capture-next loop supported) without re-feeding the
loop.
Assisted-by: Claude:claude-opus-4-8:Claude Code
With every optional slot nullable, the null-object pattern is dead. Generated
non-nullable getters return the backing field directly, which surfaced a last
tier of slots the decompiler legitimately leaves empty (omitted range operands,
an implicitly-typed array creation, unnamed parameters, an unbound generic
argument, and others) and flips them to nullable too. The machinery is then
removed entirely: the per-node null classes, the .Null statics and
VisitNullNode, AstNode.IsNull, the role null object, and Identifier.Null.
AcceptVisitor becomes unconditionally generated, and consumers move from
.IsNull to is null and from unconditional visits to ?.AcceptVisitor.
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