Cross-platform C++ compatibility checker — for embedded code and PIO libraries
C++ support varies a lot across embedded platforms. A toolchain might claim C++17, but try #include <optional> and you’ll find the macro __cpp_lib_optional is defined while the header itself doesn’t compile. For library authors the problem is worse: you’d like to use modern C++ but you don’t always know what platforms your users will target.
I built a tool that uses real PlatformIO builds (no simulation, no toolchain guessing) to test 394 SD-6 feature tests — every language feature, library type, and attribute from C++11 through C++26 — across 12 platforms: AVR, ARM Cortex-M (STM32, SAMD, nRF52, RP2040, Renesas), ESP32, ESP8266, Teensy. The results match what you’ll actually see when you build, because they are PIO builds.
What you get per (platform, standard)
| Platform | Standards | Effective Support | Usable C++ |
|---|---|---|---|
| ESP32-S3 (pioarduino) | C++11–C++26 | C++17 / 100% | C++20: 5+ 3~ · C++23: 1+ 5- |
| STM32 Nucleo F411RE | C++11–C++20 | C++14 / 97% | C++17: 5+ 3~ · C++20: 1+ 7- |
| Raspberry Pi Pico (RP2040) | C++11–C++23 | C++14 / 97% | C++17: 3+ 5- · C++20: 1+ 7- |
| AVR Arduino Uno | C++11–C++17 | C++11 / 86% | C++17: 3+ 5- |
(+ = complete · ~ = partial · - = unsupported)
Notice STM32 and RP2040 both score ~97% raw at C++14, but at C++17 STM32 has full libstdc++ (<optional>, <variant>, <filesystem>…) while RP2040 only has the language features. Raw percentages hide that; the “Usable C++” column — a curated list of high-impact tentpole features (Concepts, Ranges, <format>, Coroutines, std::optional, etc.) — makes it visible at a glance.
The tool also publishes polyfill recipes: drop-in lib_deps entries (e.g. nonstd-lite-bundle for ARM/ESP, avr-libstdcpp for AVR) that lift coverage on platforms with stripped C++ stdlibs.
Library compatibility checker
For library authors, point it at a PlatformIO library (registry name or local path) and it tells you the minimum C++ standard that works on each target platform:
# Test from the PIO registry
compat-check library ArduinoJson --report report.md
# Pin a version
compat-check library ArduinoJson@6.21.0 --report report.md
# Test a local library
compat-check library ~/my-library --report report.md
# Specific platforms only
compat-check library ~/my-library \
--platform stm32-nucleo-f411re --platform esp32s3-arduino-v3 --platform avr-uno
Output shows the minimum working C++ standard per platform plus per-example pass/fail. There’s also a GitHub Action to run this in CI on every PR.
Links
GitHub - m-mcgowan/embedded-cpp-compat-check · GitHub (source, install, action usage)- Live browsable per-platform reports: Embedded C++ Compatibility Matrix
Feedback welcome — especially platforms or libraries you’d find useful to see covered.