feat(fmt): #144 Phase 3 — delete preserveTopLevelComments (~500 LOC removal)#147
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Phase 3 migrates the ~500 LOC string-anchor post-pass in app/Main.hs
into AST-driven drain hooks in Sky.Format.Format. Every own-line
comment now routes through a semantic boundary:
* top-decl boundary (drainBefore col 0)
* value body (drainBefore bodyCol)
* let-def + let-body (drainBefore defCol)
* case-arm pattern (drainBefore branchCol)
* record / list / tuple / update field (drainBefore col; auto-multi-
line if any element has drained comments)
* lambda body (drainAnyBefore — permissive col match because
fmtArg wraps in parens and shifts bodyCol away from source col)
* if-else body (drainBefore elseCol)
End-of-decl mop-up (drainInnerUntil nextDeclLine) catches body-trailer
comments — the "prevIsBody + no blank lines" quirk-fix from the
legacy walker, but AST-side and driven by the parser's _commentPos +
_commentCol tags.
Deleted from app/Main.hs (~550 LOC):
* preserveTopLevelComments (main entry)
* collectCommentBlocks, injectComments, declKey, nextAnchorKey
* isBindingShape, collectTrailingComments, splitTrailingComment
* reattachTrailing, addHeaderBlock, addPrev/NextAnchorBlock
* filterAstEmittedBlocks, extractAstEmittedBodies,
normalizeCommentBody, astMarkerText, stripAstMarkers
Kept (belt-and-braces safety):
* fmtSafetyCheck, fmtCommentTally, fmtForceMessage — still guard
against a future regression that drops >5% of input comments.
FmtSpec's SKY_FMT_FORCE test previously verified the safety guard's
behaviour on a fixture that dropped 3 of 9 lambda-body comments in
Phase 1/2. Phase 3 preserves all comments, so that fixture no
longer trips the guard; the test now verifies the file-mode + env-
var contract mechanically (writes, exits 0, comments preserved).
Verified:
* cabal test — 993 examples, 0 failures, 6 pending (baseline count).
* CommentsSpec (18/18) + FmtSpec (3/3) + FormatSpec (14/14) green.
* #144 fixture (/tmp/sky144/StatsTest.sky): 9 comments preserved,
zero sentinel leak, idempotent.
* 40 examples: all clean-format AND byte-idempotent under two
fmt passes.
Line counts:
* app/Main.hs: 3109 → 2567 (-542)
* src/Sky/Format/Format.hs: 656 → 852 (+196 for drain hooks + helpers)
* Net: -346 lines, single source of truth for comment placement.
Co-Authored-By: Claude Opus 4.7 <[email protected]>
Claude-Session: https://claude.ai/code/session_013PZXpgCdbQ3A1eSwxCqAQZ
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Final phase of the issue #144 architectural close. Phase 1 (parser tags) + Phase 2 (Format.hs threading + Lambda drain) shipped in v0.17.7 (#146). This PR deletes the ~500 LOC string-anchor workaround from
app/Main.hsand completes the AST-driven comment placement rewrite.What ships
AST-side drain hooks added at every hole point —
Sky.Format.Formatnow handles:Deleted from
app/Main.hs—preserveTopLevelComments+ 14 helpers + AST sentinel bookkeeping (astMarkerText,stripAstMarkers,extractAstEmittedBodies,filterAstEmittedBlocks,normalizeCommentBody).Kept as belt-and-braces —
fmtSafetyCheck+fmtCommentTally+fmtForceMessagestill guards >5% drop regression.Line count
app/Main.hs: 3109 → 2567 lines (-542 LOC)src/Sky/Format/Format.hs: 656 → 852 lines (+196 LOC for drain hooks/helpers)Verification
cabal testsweep: 993 examples, 0 failures, 6 pending (baseline; no regressions)CommentsSpec18/18 +FmtSpec3/3 +FormatSpec14/14 greensky fmtself-reports issue with comments #144 fixture (/tmp/sky144/StatsTest.sky): exit 0, 9 comments preserved, zero\x03sentinel leaks, two-pass byte-identicalTest plan
cabal testfull sweep — 993/0/6 baselinesky fmton issuesky fmtself-reports issue with comments #144 fixture — 9 comments, exit 0, byte-idempotent\x03) in output🤖 Generated with Claude Code
https://claude.ai/code/session_013PZXpgCdbQ3A1eSwxCqAQZ