fix(teensy): disable LTO on teensylc release profile (Thumb-1 offset overflow)#302
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…overflow) Teensy LC is Cortex-M0+ — Thumb-1 only. Thumb-1 PC-relative loads have an immediate-offset limit (~1 KB / 0x400) that LTO output routinely overflows when whole-program optimization rearranges literal pools. On FastLED's `teensyLC` workflow, every release build now fails: .lto-tmp/ccWj7t00.s:193: Error: invalid offset, value too big (0x000004CC) .lto-tmp/ccWj7t00.s:206: Error: invalid offset, value too big (0x00000498) lto-wrapper: fatal error: make returned 2 exit status Drop `-flto=auto` from teensylc's release profile (compile_flags + link_flags). The cost is a slightly larger image but actual link success — and on Teensy LC the image budget isn't the limiting factor (64 KB flash on MKL26Z64; FastLED examples sit comfortably inside without LTO). Other Teensy profiles (teensy30/31/32/3x/4x — all Cortex-M3+/M4+/M7, Thumb-2) keep LTO. This change is targeted to MKL26Z64 only. Reference config (`configs/reference/teensylc.json`) does not list `-flto` either, so the `test_linker_flags_match_platformio_reference` guard continues to pass. All 38 `teensy::` tests pass. Repro: any FastLED `teensyLC` workflow run on master before this change (e.g. https://github.com/FastLED/FastLED/actions/runs/26686967724).
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Summary
teensyLCrelease build on master fails at the assembler withError: invalid offset, value too big (0x000004CC)on.lto-tmp/*.s, thenlto-wrapper: fatal error: make returned 2 exit status.ldr Rd, [PC, #imm]) max out around 1 KB (10-bit word-aligned immediate → 0x3FC). LTO rearranges literal pools across TUs and overshoots that on FastLED-sized projects.-flto=auto/-fno-fat-lto-objects/-fuse-linker-pluginfrom teensylc's release profile incrates/fbuild-build/src/teensy/configs/teensylc.json. Keep-Osfor size.Test plan
cargo check -p fbuild-buildclean.cargo test -p fbuild-build --lib teensy::— 38/38 (includingtest_teensylc_linker_flags_match_platformioandtest_linker_flags_match_platformio_referencewhich don't reference-fltoin the linker_flags allow-list).teensyLCworkflow should now link successfully.Fixes #301
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