rustc-LLVM error: Unexpected node to lower with 1.94.0.1

[tronical]

Steps to reproduce (requires esp-idf and espup)

espup install -v 1.94.0.1
git clone https://github.com/slint-ui/slint
cd slint/examples/printerdemo_mcu/esp-idf
idf.py build

I expected to see this happen: build succeeds

Instead, this happened:

rustc-LLVM ERROR: Unexpected node to lower
error: could not compile `slint-cpp` (lib)

Caused by:
  process didn't exit successfully: `/Users/simon/.rustup/toolchains/esp/bin/rustc --crate-name slint_cpp --edition=2024 api/cpp/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type staticlib --emit=dep-info,link -C opt-level=3 -C panic=abort -C lto --cfg 'feature="esp-backtrace"' --cfg 'feature="esp-println"' --cfg 'feature="freestanding"' --cfg 'feature="i-slint-backend-selector"' --cfg 'feature="renderer-software"' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("accessibility", "backend-linuxkms", "backend-linuxkms-noseat", "backend-qt", "backend-winit", "backend-winit-wayland", "backend-winit-x11", "default", "esp-backtrace", "esp-println", "experimental", "freestanding", "gettext", "i-slint-backend-selector", "i-slint-renderer-skia", "interpreter", "live-preview", "raw-window-handle", "renderer-femtovg", "renderer-femtovg-wgpu", "renderer-skia", "renderer-skia-opengl", "renderer-skia-vulkan", "renderer-software", "slint-interpreter", "software-renderer-path", "std", "system-testing", "testing"))' -C metadata=f6dad6c8a699bef6 -C extra-filename=-0ed129a86d65a4dd --out-dir /Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps --target xtensa-esp32s3-none-elf -C linker=/Users/simon/.espressif/tools/xtensa-esp-elf/esp-14.2.0_20251107/xtensa-esp-elf/bin/xtensa-esp32s3-elf-gcc -C strip=debuginfo -L dependency=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps -L dependency=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/release/deps --extern 'noprelude:alloc=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/liballoc-b7e44e0d4504f944.rlib' --extern 'noprelude:compiler_builtins=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libcompiler_builtins-ab55b33350ded893.rlib' --extern 'noprelude:core=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libcore-81bd102efaba58b7.rlib' --extern esp_backtrace=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libesp_backtrace-54529c1ae81d132c.rlib --extern esp_println=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libesp_println-a925e3ccf2e1078f.rlib --extern i_slint_backend_selector=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libi_slint_backend_selector-301b9a272d1afe3a.rlib --extern i_slint_core=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libi_slint_core-b4f64074f5844ffc.rlib --extern i_slint_renderer_software=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libi_slint_renderer_software-18b7ef09411f8d38.rlib --extern unicode_segmentation=/Users/simon/src/slint/demos/printerdemo_mcu/esp-idf/build/cargo/.._b0000/xtensa-esp32s3-none-elf/release/deps/libunicode_segmentation-6586c0055b1ff1bb.rlib -Z unstable-options -Cdefault-linker-libraries=yes -D warnings` (exit status: 101)

Meta

It breaks with

rustc 1.94.0-nightly (6916a992c 2026-03-13) (1.94.0.1)

but passes with

rustc 1.94.0-nightly (e04c24fce 2026-03-03) (1.94.0.0)

Unfortunately RUST_BACKTRACE=1 didn't produce a backtrace.

[MabezDev]

What about 1.94.0.2 and 1.95.0.0?

[tronical]

Breaks with 1.94.0.2. Let me try 1.95

[tronical]

1.95.0.0 works as well. Looking forward to that being released, as the default (1.94..) currently breaks.