RemObjects Pascal Script — compile under pxx (embeddable scripting)

• Type: feature / investigation (real-world compat target + feature)
• Track: P (Pascal frontend) — rung of [[feature-pascal-corpus-expansion]]
• Status: backlog
• Owner: opus-p compiler. Compiler gaps it surfaces → Track A tickets.)
• Opened: 2026-06-26
• Upstream: github.com/remobjects/pascalscript — pure Object Pascal, compiles into the exe (no external runtime files). Bytecode interpreter for an Object-Pascal subset. Delphi and FPC supported upstream.
• License: custom zlib-style + mandatory attribution (a visible "made using RemObjects Pascal Script" + where-to-find line in aboutbox/docs). Commercial OK, redistribution OK, no copyleft — clean to vendor. Keep the attribution line if we ship it.
• Relation: sibling of [[feature-synapse-compile-check]] (same "compile a real third-party Object Pascal codebase, file the gaps" loop). Likely consumer of [[feature-mimic-fpc]] / {$mode delphi} + [[feature-mode-delphi-remaining]]. Gentler cousin of [[feature-embed-dwscript-rtti]] (the RTTI stress test).

Why this is a good test case (the actual motivation)

Two wins at once:

1. Compiler conformance. A self-contained, FPC-clean, mid-size Object Pascal codebase (lexer + compiler + bytecode runtime + import glue). Compiling it on the pinned stable is a heavyweight real-world test that exercises the dialect far past our own RTL — like Synapse, but a different shape (interpreter, not networking). Lowest-friction of the Pascal scripting engines, so it goes first.
2. A feature for free. Once it builds, frank2 apps gain an embedded Object-Pascal scripting engine. We are not rolling our own — purely reusing.

Approach

• Vendor the Source/ units (or point pxx -Fu at a clone) under {$mode delphi}
  • --mimic-fpc.
• Start with the core: lexer/parser/compiler (uPSCompiler, uPSUtils) + runtime (uPSRuntime), the minimal set to compile+run a writeln('hi') script.
• Defer the optional importers (DB, classes, Lazarus) until the core runs.
• Each compile failure that is a genuine dialect/codegen gap → a Track A ticket with the exact pascal26: error; library-surface gaps → RTL work here.
• A smoke test (test/lib_pascalscript?) that compiles a tiny script string and asserts its output, wired into make lib-test.

Done when

$(PXX_STABLE) builds the Pascal Script core, and a frank2 host program runs a small script end-to-end (compile → execute → observe output) under a smoke. Stretch: host↔script binding of a hand-registered function.

License compliance (we honour it)

If we ship a demo or test app built on Pascal Script, we follow the license and give the attribution — a visible "made using RemObjects Pascal Script" line (and where to find it) in the app's aboutbox / docs / README, and we keep the upstream notice in any vendored source. Fair trade for a free engine; bake the credit line into the demo from the start, not as an afterthought.

Log

First probe 2026-06-28 (v83, --mimic-fpc)

Clone at external/pascalscript/ (remobjects/pascalscript, shallow). Core units probed with temporary lowercase copies (see [[bug-c-header-case-sensitivity-lookup]] — compiler lowercases unit name for file lookup; uPS* units have mixed-case filenames → not found without workaround).

3 Track A bugs gate the core (1 shared with Synapse, 1 new, 1 infrastructure):

1. [[bug-c-header-case-sensitivity-lookup]] — unit name lowercasing blocks all uPS* units on Linux
2. [[bug-consteval-named-type-cast]] — IPointer(expr) in const, blocks uPSUtils/uPSPreProcessor/uPSCompiler
3. [[bug-mimic-fpc-version-defines-missing]] — FPC_VERSION integer missing, blocks uPSRuntime

When Track A fixes these, re-probe for the next wall.

Open questions

• How much of Pascal Script leans on Delphi-only RTTI vs manual registration (manual RegisterMethod/AddFunction is the plain path — start there, avoid RTTI until [[feature-embed-dwscript-rtti]] tackles auto-bind).
• Which {$mode delphi} / mimic-fpc corners it hits first (per-unit mode reset, interface delegation, variants).

Probe log 2026-07-12 (opus-p)

Clone at github.com/remobjects/pascalscript, probe --mimic-fpc -Fu<clone>/Source -Fulib/rtl -Fulib/rtl/platform/posix, target unit uPSUtils. Walls burned this session:

1. const array-of-RECORD with named-field element inits ((name: 'AND'; c: CSTII_and) keyword table) — LANDED (parser, test_const_array_of_record).
2. SysUtils.CurrToStr / Currency — LANDED (sysutils shim: Currency=Double).
3. Pos(tbtstring(' '), s) — string-typed ALIAS casts were pointer reinterprets (arg matched nothing) — LANDED: value no-op passthrough.

Current wall: CheckReserved(FLastUpToken, CurrTokenId) — a managed (tyAnsiString) field passed to a Const S: ShortString param: the const frozen-string param is by-ref for ABI, the managed→frozen conversion produces a non-lvalue, and the by-ref argument check rejects it. Needs the const-frozen-string param path to materialize a conversion temp (mirror the const-record temp rule) — parser/ir slice, file/pick up next session.

Probe log 2026-07-12 (later, opus-p)

uPSUtils compiles (walls 4-8): FPC variable typecast as var arg (Cardinal(len)), Dec(Byte(p^),32) cast-deref/type-keyword targets, TObject(x).Free statement, FreeAndNil, managed→ShortString param conversion.

uPSCompiler wall: IUnknown_Guid: TGuid = (D1:0; ...; D4:($C0,...)) — pxx has NO builtin TGuid record (it's a System type; interfaces reference it). The array-valued-field record const shape itself now works (LANDED, test_record_const_array_field — TGuid's D4 array field). What's missing is the builtin TGuid type + interface-GUID semantics. -dPS_NOINTERFACES skips the GUID consts and reaches the next wall (uPSCompiler:1963, a Decl.Params shape). Pascal Script core (uPSCompiler+uPSRuntime) is a multi-wall haul past this — needs builtin TGuid, ole2/Variant surface (uPSRuntime uses ole2), and more. Parked; uPSUtils is the concrete milestone reached.

Update: builtin TGuid landed (RegisterBuiltinTGuid — System record, SizeOf 16); uPSCompiler advances past the GUID consts to uPSCompiler:1963, a {$IFDEF CPU64}...Result := False block (CPU64 IS defined; the wall is the surrounding record-field expression Decl.Params[i].Mode shape after include expansion — needs isolation). Full Pascal Script core remains a multi-wall haul (ole2/Variant for uPSRuntime, InvokeCall.inc assembly). The generally-useful spinoffs all landed: array-field record consts, builtin TGuid, variable typecasts as var args, cast-deref Dec targets, TObject(x).Free, managed→ShortString param conversion, FreeAndNil.

• 2026-07-19 (backlog sweep note) Note: external/pascalscript clone is gone from library_candidates (only synapse remains) — a resume must re-fetch upstream first. uPSUtils-compiles milestone stands (pin v209 c718f279).