Migrate the three modules that still carried private
@symbol("rt_alloc") / @symbol("rt_free") bindings onto the public
lib/os.alloc / lib/os.free surface that landed in 87c0883.
memio: 1 alloc (grow) + 2 free (grow's old-buffer drop, dynamicclose).
shlex: 1 alloc (dupstr) + 2 free (freepartial: element strs + slice
header). getopt: 1 alloc (tryparse) + 2 free (tryparse + finish).
ABI identity holds — same rt syms, same shapes, just routed through
the public surface.
rt_ensure stays inline in shlex + getopt; the slice-growth helper
isn't part of os and has no stdlib facade. Comments explain why.
Header rationale comments updated: dropped the now-stale
"lib/io ↔ lib/os C-symbol collision" framing on shlex's inlined
dupstr (that was a pre-#9 concern); reworded shlex's OOM trailer to
match lib/os.ww's documented contract (poisonous pointer, not nil,
fault on deref); fixed memio's dynamicfrom doc to reference
[[os.free]] instead of the retired rt_free name.
980_memio_run / 973_shlex_run / 982_getopt_run all green; bootstrap
byte-identical.
Both stages were eagerly evaluating RHS regardless of LHS (eager
ANDQ/ORQ on the two results). Now: eval LHS into AX, CMPQ $0 +
JE/JNE to a per-call-site label, eval RHS into AX, fall through.
AX holds the LHS sentinel on the skipped path — typechecker
already enforces bool operands.
Surfaced by lib/getopt's nil-argv guard segfault. Six new rows in
test/wcc/700_e2e.c, three of which segfault pre-fix. lib/getopt
test comment relaxed; nested-if kept as regression marker.
Mirrors Hare's getopt subject to current cgen gaps: flat `command`
fields instead of slices, struct-not-tuple `option`, error/help
constructors take out-pointers. The `parse` wrapper plus
printusage/printhelp/printsubcmds are deferred (need fmt.fprintf
with {}-interpolation, which lib/fmt doesn't expose yet). SUBCMD
machinery dropped entirely per Drew — accept-but-inert would have
been a silent-misuse hazard.
Graduates in one go when cgen tasks #4#5#6#7#9#10#11#14
land. File header names the three surface sweeps that will follow.
Surfaces task #15 (w6c: && doesn't short-circuit, nil-arg deref
in test exposed it).
