Abs / Sqr System intrinsics missing

• Type: feature (language) — Track A
• Status: DONE — 2026-06-23 (Abs + Sqr, int + float).
• Opened: 2026-06-23
• Found by: differential probe vs FPC (Abs(-5), Sqr(7) -> "undefined").

Problem

Abs(x) and Sqr(x) are System intrinsics (no uses) and are unimplemented. (Succ/Pred/Odd were added the same session as pure single-use rewrites; Abs/Sqr are deferred because a naive rewrite is incorrect.)

Why not a trivial rewrite

• Sqr(e) = e*e uses e TWICE — a naive fold double-evaluates a side-effecting argument (Sqr(f())). Needs the argument bound to a temp.
• Abs(e) needs a conditional (if e<0 then -e else e), not a pure expression — needs a temp + branch or a runtime helper, and must cover both integer and float operands.

Fix options

A runtime helper (__pxxAbsInt/__pxxAbsFloat, __pxxSqr*) in the builtin unit (with the usual pre-scan pull on abs(/sqr(), mirroring the string Copy/Delete intrinsics), or an expression-temp mechanism so the argument is evaluated once. Gate: make test + FPC oracle (int + float, negative/zero/positive).

Fix log

• 2026-06-23 — DONE (3604594) via builtin helpers (same pattern as string Delete/Insert): __pxxAbsInt/__pxxAbsDbl/__pxxSqrInt/__pxxSqrDbl in builtin.pas; ParseFactor lowers Abs/Sqr to the int or float helper by the argument type (eval-once), pre-scan pulls the builtin unit on abs(/sqr(. Test test/test_abs_sqr.pas, FPC oracle-matched (int + float). make test + cross-bootstrap byte-identical.