Pascal real-world corpus expansion — the ladder Track P never had

• Type: feature — umbrella (frontend stress corpus)
• Track: P (Pascal frontend; shares lexer.inc/parser.inc with A, so bugs found land as Track P — A-gated — or Track A core)
• Status: backlog — filed 2026-07-10 (C wound down to 2 open bugs; Pascal neglected by comparison — user call).
• Owner: —

Why (the gap)

The C frontend got a driven ladder (c-testsuite → zlib → cjson → lua → sqlite → tcc, all green). Pascal never got one. What exercises the Pascal frontend today:

• self-host — maximal, but only the thin subset the compiler writes itself in (careful classes, no generics, hand-picked RTL). It proves the subset, not the dialect.
• 629 test/*.pas — hand-written feature tests. Valuable, but not a real program's worth of features interacting.

Track P owns the full dialect — classes, generics, properties, exceptions, mode-Delphi, real RTL semantics, "far past what self-host needs." Only real-world Pascal stresses that, and it's currently scattered across a few prio-45 tickets + two rainy-day probes. This umbrella gives Pascal a ranked next --track P queue, same as C had.

The underused asset

PXX is FPC-seeded and FPC-faithful, so FPC-compatible code should compile at high fidelity — and FPC ships its own test suite: thousands of tests/test/*.pp conformance programs. That is the c-testsuite analog, but authoritative and far larger, and today only a rainy-day probe touches it.

The ladder ("variation is good" — interleave conformance + real apps)

1. FPC test-suite subset — conformance corpus, the c-testsuite analog. Systematic full-dialect coverage, ready-made. Do first — [[feature-pascal-corpus-fpc-testsuite]].
2. Synapse — real networking lib, already vendored in external/synapse/. I/O + classes + RTL. [[feature-synapse-compile-check]].
3. A real self-contained tool — e.g. PasDoc (doc generator: OO, RTL-heavy, standalone). The "real app compiles" flex. (candidate — file when reached.)
4. PascalScript / DWScript — embeddable script engines, heavy RTTI/OO/generics = the hard rung (tcc-equivalent). [[feature-embed-pascal-script]] · [[feature-embed-dwscript-rtti]].
5. Pascal chess engine — perft oracle already cross-validates the C and Rust chess ([[feature-c-corpus-chess]]); a Pascal one = three frontends, one oracle. Cheap, high-signal cross-language check. (candidate.)
6. Lighthouse (stretch): compile FPC's own compiler pp.pas — the "tcc self-compiles" analog. [[goal-compile-fpc-compiler]] · [[experiment-compile-fpc-as-stress-probe]] (stay rainy-day until the lower rungs are green).

Method (mirror the C corpus)

Per rung: vendor the source (installer fetcher, pinned commit, gitignored) → compile with the current pxx → each failure = one narrowed frontend bug ticket (Track P if lexer/parser/dialect; Track A if IR/backend/core) → burn the skip list ticket by ticket → rung green → next rung. Land bugs green; dialect policy = FPC-faithful default, extensions behind a switch.

Gate

Frontend/dialect fixes carry Track P's gate = make test + self-host byte-identical (shared lexer.inc/parser.inc), plus cross where a backend is touched. Corpus programs run to correct output (compare against FPC where an oracle helps).

Links

Mirror of [[feature-c-corpus-expansion]] · dialect policy [[project_fpc_compat_next_queue]] · [[project_synapse_progress]].