ESP32 C++17 toolchain missing std::optional

Rather use gnu++17, I’ve seen it needing GNU extensions.

Works for me.

[env:esp32doit-devkit-v1]
platform = https://github.com/tasmota/platform-espressif32/releases/download/v2.0.2idf/platform-espressif32-2.0.2.zip
board = esp32doit-devkit-v1
framework = arduino
build_unflags = -std=gnu++11
build_flags = -std=gnu++17
#include <Arduino.h>
#include <optional>

void setup(){}
void loop(){}

>pio run
Processing esp32doit-devkit-v1 (platform: https://github.com/tasmota/platform-espressif32/releases/download/v2.0.2idf/platform-espressif32-2.0.2.zip; board: esp32doit-devkit-v1; framework: arduino)
------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/esp32doit-devkit-v1.html
PLATFORM: Espressif 32 (2.0.2) > DOIT ESP32 DEVKIT V1
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (esp-prog) External (esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES:
 - framework-arduinoespressif32 2.0.2
 - tool-esptoolpy 1.30200.211025 (3.2.0)
 - tool-mklittlefs 1.203.210628 (2.3)
 - toolchain-xtensa-esp32 8.4.0+2021r2
LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 30 compatible libraries
Scanning dependencies...
No dependencies
Building in release mode
Compiling .pio\build\esp32doit-devkit-v1\src\main.cpp.o
Generating partitions .pio\build\esp32doit-devkit-v1\partitions.bin
Archiving .pio\build\esp32doit-devkit-v1\libFrameworkArduinoVariant.a
Indexing .pio\build\esp32doit-devkit-v1\libFrameworkArduinoVariant.a
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\Esp.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\FirmwareMSC.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\FunctionalInterrupt.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\HWCDC.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\HardwareSerial.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\IPAddress.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\IPv6Address.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\MD5Builder.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\Print.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\Stream.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\StreamString.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\USB.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\USBCDC.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\USBMSC.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\WMath.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\WString.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\base64.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\cbuf.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-adc.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-bt.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-cpu.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-dac.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-gpio.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-i2c-slave.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-i2c.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-ledc.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-matrix.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-misc.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-psram.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-rmt.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-sigmadelta.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-spi.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-time.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-timer.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-tinyusb.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-touch.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\esp32-hal-uart.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\firmware_msc_fat.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\libb64\cdecode.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\libb64\cencode.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\main.cpp.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\stdlib_noniso.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\wiring_pulse.c.o
Compiling .pio\build\esp32doit-devkit-v1\FrameworkArduino\wiring_shift.c.o
Archiving .pio\build\esp32doit-devkit-v1\libFrameworkArduino.a
Indexing .pio\build\esp32doit-devkit-v1\libFrameworkArduino.a
Linking .pio\build\esp32doit-devkit-v1\firmware.elf
Retrieving maximum program size .pio\build\esp32doit-devkit-v1\firmware.elf
Checking size .pio\build\esp32doit-devkit-v1\firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [          ]   4.2% (used 13668 bytes from 327680 bytes)
Flash: [=         ]  12.5% (used 163249 bytes from 1310720 bytes)
Building .pio\build\esp32doit-devkit-v1\firmware.bin
esptool.py v3.2
Merged 2 ELF sections
=====================[SUCCESS] Took 11.05 seconds =====================
3 Likes