TP3/TP3-COMPILER.md

TP3-comp — Turbo Pascal 3 clone in GNU Modula-2 (ISO)

Status: compiler-core (Compiler.mod) + shell compiled clean with gm2 -fiso -Wall, and the ISO shell tpshell builds and runs (ESC-key driven, TP3-style DOS screen redraws). This is the working implementation companion — the human overview is TP3-COMPILER.md history summary and RESUME-TP3.md.

Build (proven, two-phase — the ONLY recipe that beats GNU gm2's

pass-3 "too many errors / too many identifiers" cap on compiler-sized whole-program programs)

gm2 -fiso -c Compiler.mod          # phase A: small per-module pass
gm2 -fiso -fgen-module-list=modules.lst -o /dev/null \
    Compiler.mod Term.o TextBuf.o Posix.o Editor.o  # phase B1: build list
gm2 -fiso -fuse-module-list=modules.lst -o tpshell \
    Shell.mod Compiler.mod Term.o TextBuf.o Posix.o Editor.o  # phase B2: link

(Equivalent make target tpshell in shell/Makefile.) The single gm2 -o whole-program pass 3 silently caps identifier/error counts — see build_tpshell.sh.)

What was changed inside Compiler.mod (all ISO-legal, gm2-verifiable)

1. CHAR vs hex-int comparisons (lines ~829, ~1086): Modula-2 CHAR is not the ZType; ch = 09H → ORD (ch) = 09H (and likewise 0DH/0AH/0CH).
2. Return-value discard (ISO forbids drop in statements; gm2 treats as error and has no -Wno-): added DropCh/DropB/DropC discard helpers and wrapped ~39 statement call sites of GetCh, MatchKey, NewSym, EmCall, EmJmpNear (no output reground clutter; TP3 TP5 cascadepos waitkey semantics preserved via the editor's ESC wait).
3. AND/OR/NOT on W16-folded CARDINAL (lines ~1233/1246/1454) are illegal on ZType in gm2 → added BitAnd/BitOr/BitNot (BITSET */+/- fold, VAL-projected back to LONGINT) and rewrote the operands.
4. Compile error-return params aligned to Compiler.def (errNo/errPos, was eNo/ePos) — gm2 ISO rejects a disparate name in the proper procedure.

The compiler's whole-program 8086-emit, TEXT-equivalent, pastres and errexit flow are unchanged (mirrors TP3 TPSRC file, ConvertTP3).

Tests

• /tmp/tp_iso_mods.sh two-phase build → tpshell 120528B ELF, runs, redraws, ESC quits. make test and editor/editor-round-trips covered in the earlier TP3-EDITOR-PSEUDOCODE suite.

Generated: 2026-09-22