obj.Free rejected — built-in TObject has no Free method

• Type: bug / feature (compiler object model — Track A)
• Status: backlog
• Owner: —
• Opened: 2026-06-21
• Relation: next examples/chess blocker after feature-eof-stdin-builtin (done). Chess now parses to chess.pas:961.

Problem

eng.Free;   { pascal26:961: error: unexpected token () / Expected: := }

A parameterless method call on a declared method works (f.Bar; parses), so the gap is specific to Free: the built-in TObject (classes.pas notes "TObject is built in") exposes no Free method, so obj.Free is parsed as a field-access lvalue and the parser then demands :=.

Minimal repro:

type TFoo = class procedure Bar; end;
...
f := TFoo.Create;
f.Bar;    { ok }
f.Free;   { error: Expected := }

Direction

• Give the built-in TObject a Free method (the FPC idiom: if Self <> nil then Destroy), calling the destructor then releasing the instance heap block. PXX already has class instantiation + destructors + the heap; this wires the standard Free entry point.
• Track A owns the built-in TObject / object model. If TObject is instead grown in RTL, coordinate with Track B — but the "built in" comment suggests the compiler.
• Watch the error path: an unknown .Method; should not silently become an lvalue awaiting :=; a clearer "unknown method" diagnostic would help.

Acceptance

• obj.Free; compiles and frees the instance (destructor runs; double/nil Free is safe).
• examples/chess advances past chess.pas:961.

Log

• 2026-06-21 — filed (self-discovered as the next chess blocker after Eof).
• 2026-06-21 — DONE (commit 562eb95). Built-in obj.Free desugars to the nil-guarded FPC idiom if obj <> nil then begin [obj.Destroy;] FreeMem(obj); obj := nil end (GenMakeFreeObject in parser.inc; statement-parser intercepts plain obj.Free;/obj.Free end on a non-record class instance with no user Free method). Destroy is dispatched (virtual when declared) only when the class or an ancestor has one; nil-ing the var makes a second Free a safe no-op. Verified: double-free + virtual-destructor repro runs correctly; examples/chess compiles fully (past :961) and runs. make test green — self-host fixedpoint byte-identical, threadsafe byte-identical, asm-emit all OK. Limitation: only a plain obj.Free where obj is a simple class-instance var is intercepted (covers chess + the repro); arr[i].Free / rec.f.Free still need a user Free method.