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FPC seed build fails after Lua C frontend helper additions

Symptom

make bootstrap currently fails in the initial FPC seed compile before the self-host stages:

symtab.inc(979,27) Error: Identifier not found "TypeSize"
ir.inc(901,15) Error: Identifier not found "CNodeDecaysToPointer"

This is not a self-host stability failure. It is an include-order / forward declaration issue exposed by helper calls added during the Lua C frontend work:

Self-hosted compiler/pascal26 has historically accepted this shape, but FPC does not. Fix should preserve the include model and avoid moving large chunks unless necessary.

Root cause (settled 2026-06-27)

FPC is strictly single-pass: at a call site it resolves a routine only if it has already seen that routine's header above in the linear (post-{$include}) text. A header counts as "seen above" exactly four ways: (1) full definition above, (2) a forward; above, (3) it sits in an interface section — this unit's or any uses-d unit's (all interfaces compile first), (4) it's a method published by a class/record type decl above. None of those → identifier not found. FPC does not rescan; it does not auto-forward implementation/ program routines; mutual recursion genuinely needs forward.

PXX is more permissive: the declaration pre-scan ([[feature-declaration-prescan]]) registers every top-level header first, so order never matters and forward is never required. That leniency is what masks these two seed breaks until make bootstrap runs the real FPC.

Both failures are the identical shape — header not above the call:

(Historical note: the LowerCase case that motivated the pre-scan was NOT whole-section magic — under FPC LowerCase came from SysUtils' interface (rule 3); PXX used its own copy defined later. Different routines, not a rescan.)

Solution (chosen — matches the existing inline-forward practice)

compiler.pas already hand-maintains unconditional inline forward; decls at include boundaries (AsmB/AsmI16..64 before x64enc, CPreprocess before parser, GetOrAlloc* after ir) purely to satisfy FPC's rule — PXX tolerates a redundant forward. These two are simply forwards that were forgotten when the Lua C-frontend helpers landed.

Fix = consolidate into a new compiler/forwards.inc, included once before {$include symtab.inc} (both signatures use only base / defs.inc types, so that single early point is above both uses):

{ FPC-seed-only forward decls. PXX prescans the whole program and never needs
  these; FPC compiles top-down and does. Signatures MUST stay byte-identical to
  the bodies. }
function TypeSize(tk: TTypeKind): Integer; forward;
function CNodeDecaysToPointer(node: Integer): Boolean; forward;

Include guard — step 1 ships {$ifdef FPC}; widen to {$if defined(FPC) or defined(PXX_REQUIRE_FORWARD)} once [[feature-require-forward-strict-mode]] lands (so PXX-strict sees the same forwards and becomes an FPC-free seed proxy).

Then delete the now-redundant cparser.inc:19 forward — forwards.inc provides it earlier; two forward; for one routine is an FPC error.

Acceptance

Log