writeln of a ShortString/frozen-string PARAM prints wild memory

• Type: bug (codegen — frozen-string by-ref param read) — Track A
• Status: done ([[feature-embed-pascal-script]]).

Symptom

procedure Check(const S: ShortString);
begin
  writeln('got=', S, ' len=', Length(S));   { S dumps env/stack memory }
end;
var f: ShortString;
begin
  f := 'HELLO';
  Check(f);   { got=<garbage>, but len=5 and S = 'HELLO' compare TRUE }
end.

Length(S) and equality comparison read the param correctly (slot address → length word), but the WRITELN path reads from a wrong address and dumps process memory. Pre-existing (repros on pinned v207 and in default mode, no --mimic-fpc needed, no managed conversion involved).

Where hit

Pascal Script's uPSUtils lexer (Const S: ShortString params). Any FPC code printing a shortstring param.

Acceptance

writeln(S) of a tyFixedString/tyShortString param prints the value on all paths (direct + after the managed→frozen conversion temp of 2026-07-12); compile-run test; self-host byte-identical.

Log

• 2026-07-12 — resolved, commit HEAD.