Kris Austin 7d17400443 fix: dangling static lambda crashes support G-code export on repeated slices (#14677) ...

GCode::extrude_support declared its per-path speed helper as a function-local
static lambda that captures `this` by reference. The closure is built once, on
the first extrude_support call, and reused for the rest of the process, so a
second G-code export in the same process runs the helper against a `this` from
the first export's stack frame, which has already returned.

The stale `this` flows through NOZZLE_CONFIG(...) -> cur_extruder_index() ->
GCodeWriter::filament(), reading a garbage current-extruder id and indexing
with it. It is silent whenever the reused stack still holds a usable pointer,
and an order-dependent SIGSEGV otherwise; AddressSanitizer reports it as a
stack-use-after-return in GCodeWriter::filament(). It is the only static
capturing lambda in libslic3r.

Drop static so the closure is rebuilt each call against the live frame. Add an
fff_print regression test that slices a support object twice in one process; it
fails without the fix (stack-use-after-return under ASan) and passes with it.

2026-07-09 08:56:03 +08:00

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