# Pascal corpus census

`Sources/Dezip/` is an external collection, not part of the build.  The
working tree now retains only `pascsrc/`: **71 `.pas` files**, all of which
compile.  The original dump contained **4,919 `.pas` files** (77 MB, about
354k lines); its census below is kept as history, not as the current result.

## Method

Every file is compiled separately with `shell/compiletest`, in a fresh process
and with a 5-second timeout.  Separate processes matter: one crashing source
must not hide the rest.  The repeatable check is `tests/corpus_check.py`,
wired into `tests/run_all.sh` when `Sources/Dezip/pascsrc` exists.

## Historical census (pre-cleanup)

| result | count |
|---|---:|
| compiles | **49** |
| errors | **4,870** |
| crashes/timeouts | **0** |

By error code:

| code | meaning | count |
|---|---|---:|
| 41 | unknown construct/identifier | 4,335 |
| 90 | include file not found | 418 |
| 102 | not implemented | 48 |
| 1 | syntax / semicolon | 39 |
| 30 | simple type expected | 20 |
| 56 | type mismatch | 9 |
| 99 | compiler overflow | 1 |

The useful subset is `pascsrc/`, which is the classic TP3 example material:
**44 of 84 compile**.  The SWAG tree is 4,473 files, almost all FreePascal or
Delphi units; only 5 compile.

## Bugs found by the corpus

- **Typed constants containing an array of strings crashed the compiler.**
  A one-character element such as `'I'` is scanned as a `CHAR` scalar, not a
  string, so `DefConst` took the integer path and shifted a 16-bit value through
  `divi` until it became zero: `SIGFPE` in `DefConst`.  The array element type
  is now consulted; a scalar element of a `STRING` array is stored as a
  one-character string.  `t118_strconstarray` compiles and prints `''`, `I`,
  `II`.
- This bug was also hit by `Roman2.pas` in the SWAG tree.  It now gets a normal
  diagnostic (`Word` is not yet a type) instead of killing the compiler.

## Main blockers visible in the census

1. `uses`/`unit` imports.  Most SWAG files cannot even reach a declaration
   after their `uses` line.
2. The wider integer family: `Word`, `LongInt`, `ShortInt`, `Single`, `Double`.
3. Turbo extras such as `absolute`, `Printer`, `Dos`, `Mem`/`Msdos`, and
   `Addr` beyond the currently supported pointer paths.
4. Includes whose names or search paths differ from the file's own directory
   (`ERROR 90`, 418 files).

The surviving 71 files are wired into `run_all.sh` through
`tests/corpus_check.py`; an absent `Sources/` tree is a skip, because that
material is user-owned and untracked.  The current result is **71 / 71 OK**.

## Conservative cleanup

The obvious non-TP3 material was removed:

- the whole `Dezip/swag-pascal-master` tree and its
  `swag-pascal-master.zip`;
- 416 `.pas` files outside that tree that declare `unit`, use `uses`, or carry
  FreePascal/Delphi markers;
- 42 zip archives whose Pascal entries were **all** marked in that way.

Mixed archives — including `pascsrc.zip`, which also contains the compiling
TP3 examples — were deliberately kept during that first pass.

Before cleanup: **6,810 files**, **4,919 `.pas`**, **907 zips**.
After the conservative pass: **1,731 files**, **71 `.pas`**, **858 zips**.

The final working-tree cleanup removed `Sources/simtel` and every
`Sources/Dezip` entry except `pascsrc/`.  The tree is now **78 files /
71 `.pas` / 0 zips**, and all 71 Pascal files compile.

The remaining 71 Pascal files compile as **71 OK / 0 errors** with the
current compiler.  The upgrades cover long identifiers, named labels,
`Addr`, field widths, nested arrays, negative bounds, forward pointer types,
`NIL`, forward procedure parameters, nested record fields, whole-record/array
assignment, integer `/` as REAL division, `Ord`, `Succ`/`Pred` on enums, and
enum subranges, a leading set constructor in a set expression, Round/Trunc,
integer-to-REAL assignment, SHL/SHR, address-based pointers, char arrays,
Msdos/Intr, and variant records.  The TP3-feature gaps are now closed; the
corpus is clean:

The final batch closed dynamic set constructors (`[Storage[Index]]`),
text-file width formatting (`Write(File, integer:width)` and string widths),
`Getdir`/`Seg`/`Ofs`/`Mem`, and text-file numeric `Read`/`Readln`.