The debug-step node bracket (MarkNodeStart/try/finally/MarkNodeEnd) was copied
into every hand-written WriteTo override and re-emitted by the T4 generator, so
a newly added instruction could silently omit it and lose step highlighting with
no compile error or test failure. Seal WriteTo on ILInstruction to apply the
bracket once and delegate to a new abstract WriteToCore; move every override
(hand-written and generated) to WriteToCore without the wrapper. Rendered output
is unchanged -- the marks are no-ops unless the output tracks nodes.
Assisted-by: Claude:claude-opus-4-8:Claude Code
The C# debug-steps view highlights and centers the exact AST node a
transform changed; the ILAst view already had the step tree and
replay-at-step but produced no highlight. Bring it to parity.
IL rendering has no token-writer seam like the C# output visitor, so
per-instruction text spans are recorded by bracketing
ILInstruction.WriteTo via a new INodeTrackingOutput. The dominant
inst.ReplaceWith(newInst) transform pattern detaches the instruction
passed to Step, so ILTransformContext gains EndStep to record the
produced instruction; Stepper additionally records the position's
ancestor chain as fallback candidates before the step-limit throw, so
the "show state before" view -- which halts at the selected step --
still resolves to a surviving ancestor (ultimately the ILFunction).
The highlight-range resolver is shared with the C# language.
Assisted-by: Claude:claude-opus-4-8:Claude Code
TokenRole was a printer-side descriptor whose only jobs were holding a token's
text and giving the writers an identity to single out specific tokens. The text
becomes plain const strings on the nodes, and the few identity checks are
reexpressed as node-stack context: interpolation braces are recognized by an
Interpolation on the writer's stack, record class versus struct coloring keys
off TypeDeclaration.ClassType, and the accessor/this/base/override cases fall
out of the surrounding node. WriteKeyword/WriteToken drop the descriptor
parameter. The constants are named for what the token is: a keyword, a symbol
token, or a modifier.
Assisted-by: Claude:claude-opus-4-8:Claude Code