# Step: M2make-driven bootstrap + explicit cross-stage FileIO

Tags `v3-m2make-bootstrap`. Suite **111/111**.

## What changed

`bootstrap/fixpoint.sh` now drives the fixpoint with **M2make** (the
build-order front-end) instead of a hand-written session file list, and
makes the stage-dependent `FileIO` choice explicit:

- **Stage 1 (gm2)**: `compiler/build.sh` with the **host** `FileIO`
  (`compiler/src/FileIO.def/.mod`, GNU-Modula-2 specific).
- **Stage 2/3 (V3)**: the compiler sources are regenerated without `-m`
  (real `FORWARD`s) and **staged without `compiler/src/FileIO*`**, with
  `runtime/syslib` on the `-I` path — so M2make resolves `FileIO` to the
  **self-hosted** `runtime/syslib/FileIO`. M2make orders the session and
  runs `M2` + `qbe` + `cc`.

M2make is built if missing (`tools/m2make/build_m2.sh`, `b_v3/M2make`).

## Result

```
=== Stage 1: gm2 build (host FileIO, CR -m) ===
=== m2s2 built by /tmp/opencode/m2s1 ===
=== m2s3 built by /tmp/opencode/m2s2 ===
FIXPOINT OK: stage2.ssa == stage3.ssa (1991297 bytes)
```

(The image is a little smaller than the earlier hand-written session's
1,991,439 bytes because M2make's topological order differs — irrelevant
to the fixpoint, which compares the two V3 stages.)

## Files

`bootstrap/fixpoint.sh`.