Compilation fails for trivial C program with Adafruit Metro M0

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2

So you are working with the Arduino framework.

…but implement main()? The Arduino core already implements that, and calls into the standard user functions setup() and loop() after that. Overriding main like this very likely not going to work at runtime (in a sensible way, since all low-level initializion, including that of the C library, is skipped).

A correct “trivial program” for your platformio.ini is an empty Arduino sketch in a .cpp file (Arduino is a C++ framework, not C.).

#include <Arduino.h>
void setup() {}
void loop() {}

Can’t reproduce that, on the same Atmel-SAM platform 6.3.1 with the same code + platformio.ini, on either Windows or Linux.

$ pio run
Processing adafruit_metro_m0 (platform: atmelsam; board: adafruit_metro_m0; framework: arduino)
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Verbose mode can be enabled via `-v, --verbose` option
CONFIGURATION: https://docs.platformio.org/page/boards/atmelsam/adafruit_metro_m0.html
PLATFORM: Atmel SAM (6.3.1) > Adafruit Metro M0 Expresss
HARDWARE: SAMD21G18A 48MHz, 32KB RAM, 256KB Flash
DEBUG: Current (atmel-ice) External (atmel-ice, blackmagic, jlink)
PACKAGES:
 - framework-arduino-samd-adafruit 1.7.2
 - framework-cmsis 2.50400.181126 (5.4.0)
 - framework-cmsis-atmel 1.2.2
 - toolchain-gccarmnoneeabi 1.90301.200702 (9.3.1)
LDF: Library Dependency Finder -> http://bit.ly/configure-pio-ldf
LDF Modes: Finder ~ chain, Compatibility ~ soft
Found 11 compatible libraries
Scanning dependencies...
No dependencies
Building in release mode
Compiling .pio/build/adafruit_metro_m0/src/main.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduinoVariant/variant.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/IPAddress.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/Print.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/Reset.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/SERCOM.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/Stream.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/Tone.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/USB/CDC.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/USB/PluggableUSB.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/USB/SAMD21_USBDevice.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/USB/USBCore.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/USB/samd21_host.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/Uart.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/WInterrupts.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/WMath.cpp.o
Archiving .pio/build/adafruit_metro_m0/libFrameworkArduinoVariant.a
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/WString.cpp.o
Indexing .pio/build/adafruit_metro_m0/libFrameworkArduinoVariant.a
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/abi.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/avr/dtostrf.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/cortex_handlers.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/delay.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/hooks.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/itoa.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/main.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/math_helper.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/new.cpp.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/pulse.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/pulse_asm.S.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/startup.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/wiring.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/wiring_analog.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/wiring_digital.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/wiring_private.c.o
Compiling .pio/build/adafruit_metro_m0/FrameworkArduino/wiring_shift.c.o
Archiving .pio/build/adafruit_metro_m0/libFrameworkArduino.a
Indexing .pio/build/adafruit_metro_m0/libFrameworkArduino.a
Linking .pio/build/adafruit_metro_m0/firmware.elf
Checking size .pio/build/adafruit_metro_m0/firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM:   [          ]   2.6% (used 856 bytes from 32768 bytes)
Flash: [          ]   1.8% (used 4588 bytes from 262144 bytes)
Building .pio/build/adafruit_metro_m0/firmware.bin
=============== [SUCCESS] Took 3.31 seconds ===============

Which means either problem is Mac specific, or you have an unluckily named additional header file in the project that interferes with the SDK, or you have a corrupt SDK download. Try removing /Users/me/.platformio/packages/framework-arduino-samd-adafruit/ and /Users/me/.platformio/packages/framework-cmsis-atmel/ to trigger a redownload of that.

Note that if you don’t want to use Arduino, you can setup an PlatformIO project with only the (Atmel-)CMSIS device headers that you can program against in pure C. There’s a topic and example for that at Bare metal on arduino due / atmelsam. But using the Atmel-CMSIS headers also possible in Arduino, since it includes Atmel-CMSIS, you just have Arduino compiled in as a side-effect.

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