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+# Lower phase — L6 status (2026-10-05)
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+
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+Branch **`ast-stage-c`**. L6 = "classes/vtables, imports, nested modules".
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+
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+## Landed
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+
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+**Nested modules** (`f82f72b`, tag `v3-lower6-nested`)
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+- `CanDecl` accepts a nested `NkUnit` (with no imports).
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+- `LowerDecls` emits the nested unit's declarations and, when it has a
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+ `BEGIN` body, `BeginInit`/body/`EndInit` (registering `<nested>_init`
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+ so the enclosing `BeginBody` calls it).
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+- `ReenterGlobals` re-registers a nested module's non-exported globals in
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+ the still-open enclosing module scope, so `QbeGen.GlobalRef` resolves
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+ their `"<outer>_<name>"` symbols after the nested scope has been popped.
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+- `lower_ok t_nestedmod.mod` byte-matches. Suite 194/194; FIXPOINT OK
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+ (3,328,857 bytes).
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+
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+## Blocked / remaining
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+
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+### Imports — blocked by the session-image model
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+`-lower` is invoked only from `ProgModule`'s END (`M2.atg`), so Lower
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+re-emits **only the last unit**. But a session's image is accumulated
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+across all units (`sessBuf`): a program that `IMPORT`s a module pulls
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+that module's procs/init/globals into the *same* `gen_ssa/<Prog>.ssa`.
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+So re-emitting just the program cannot byte-match.
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+
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+Supporting imports therefore needs a **mechanism change**: lower *every*
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+unit (definition/implementation/program) and accumulate a session image
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+(mirroring `sessBuf`), or otherwise compare per unit. That is the same
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+mechanism the **L7 flip** needs, so it is the natural next structural
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+step. Qualified names (`M.x`) additionally need `SymTab.MaterializeAlias`
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+at lowering time (module scope is open — workable) and qualified-call
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+resolution in `LowerCall` (currently `CalleeName` reads only the base
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+ident).
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+
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+### Classes/vtables — large, single-unit, verifiable
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+Surface: `NkClassDecl`/`NkFieldDecl`, `CLASS IMPLEMENTATION`, method
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+binding (`obj.Method` + `ArmRecv`), virtual dispatch, inheritance, `NEW`
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+for classes, vtables (`QbeGen.EmitVTables`), `THIS`. Independent of
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+imports, so it can be byte-verified with `lower_ok` on a self-contained
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+class program.
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+
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+## Suggested order
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+1. Classes/vtables (verifiable now).
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+2. The per-unit lowering mechanism (unblocks imports and is the L7
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+ prerequisite).
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