# Stage C cleanup — dead forward-variable text-patching

Tag `v3-stage-c-cleanup`, branch `stage-c-cleanup` (off `generics-inc1`).
Suite **189/189**; fixpoint **OK** (**3,424,520 bytes**).

## What was deleted (dead)

The L7 flip made `Lower` resolve forward designators **by name** at
lower time, so the QbeGen text-patching that rewrote placeholder
symbols in the buffered image became unreachable:

- `FwdPatchAll` was driven by `fwdSite[k]`, set only by `QbeGen.FwdPatch`
  — which had **no callers** (`FwdDesignator`/`FwdAddrOper` were already
  gone), and `nFwd` was never incremented.
- So `FwdPatchAll` and everything it alone called was dead.

**Deleted from `QbeGen.mod` (146 lines total with the SymTab trim):**
`FwdMangle`, `FixLoadClass`, `FixStoreClass`, `BufReplaceAll`,
`FwdPatchAll`, the `nFwd`/`dbgFwd`/`fwdSite`/`fwdOper`/`fwdGlob` vars,
and the `FwdPatchAll;` call in `EndModule`.

**Deleted from `SymTab.mod`:** the dead `FwdVarName1` wrapper.

No `QbeGen.def` exports existed for any of these.

## What remains, and why (live, not dead)

The grammar/SymTab half is **load-bearing** and was *not* deleted:

| Symbol | Role |
| --- | --- |
| `SymTab.FwdVarRef` | a not-yet-declared module global referenced inside a body becomes a placeholder, so parsing does not report 201 prematurely |
| `SymTab.FwdVarName`/`FwdVarType`/`FwdVarResolve` | module-end check: still undeclared ⇒ **201** |
| `SymTab.IsFwdVar` | parse-time leniency (the placeholder is `ClPtr`-typed, so type checks must not reject it) |
| grammar `FwdVarNote`/`FwdVarFlush` | records forward refs; runs the 201 check at module end |
| grammar `Design` forward branch | emits the `@` marker (AST `op=1`); `Lower` then resolves it by name |

The reason this half survives is the same finding that merged Stage B
into Stage C: **parse-time checks run before a module's later
declarations exist**.  The AST/Lower pass resolves the reference
*afterwards*, but the *tolerance* and the *201 reporting* still have to
happen during parse.  Removing them needs the dedicated **resolve/check
pass** (see `docs/plan-two-phase.md` §2, step 2), which is not built.

## Correctness

The image got **smaller** (3,554,237 → 3,424,520 bytes) and byte-stable
across the fixpoint, confirming the deleted code was never executed.

## Still open (unchanged)

- L7 item 7 (`SaveSession`/`RestoreSession`/`SetNoEmit`) — blocked on the
  grammar's last suppressed writers.
- The resolve/check pass, which would also let `FwdVar*`/`IsFwdVar` go.