Two crash paths surfaced by the null-object -> nullable-reference migration of the
C# AST. A void 'return;' forced into lambda syntax NRE'd on
ReturnStatement.Expression.Detach() now that Expression is nullable; the body now
falls through to the block form, matching the existing guards in CallBuilder and
InferReturnType. Separately, the location-setting token decorator routed a parentless
print-only node (e.g. the detached name-token clone of a renamed constructor) into the
child setter as SlotKind.None, which throws since the Role hierarchy was removed; such
nodes have no slot and are now skipped. A regression test covers the decorator path.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Source locations were virtual, computed by recursing to the first and last
child, whose leftmost and rightmost leaves are token nodes; sequence-point
coordinates likewise came from reconstructed token nodes. Store locations as
fields assigned while printing, and derive sequence-point coordinates from the
surrounding real nodes plus the decompiler's fixed formatting, so neither
depends on token children. The using/foreach await modifier becomes a plain
bool field. Characterization gates lock the emitted locations and PDB
coordinates, which are unchanged.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The InsertMissingTokensDecorator path (TokenWriter.CreateWriterThatSetsLocationsInAST)
reconstructs token nodes and assigns source locations onto the AST, feeding PDB
sequence points and GUI navigation. The Pretty suite never drives it, so it had no
coverage at all. Before reworking the token model, lock its observable consequences:
the located path emits the same text as the plain path, real nodes receive ordered
locations, location-based navigation resolves into the method body, and sequence
points are produced for a method body.
Assisted-by: Claude:claude-opus-4-8:Claude Code
Siegfried Pammer