Serial.write(0x00) fails to compile

just stumbled across a weird behavior. If I send a 0x00 via Serial.write(), compiler fails with the below error. Values other than 0x00 are fine, and also sending a variable with value 0x00 (see attached demo)

Notes:

- This occurs for all Serials (0-3) on Arduino Due. Mega and Uno are ok
- I am running Linux x64 with IDE 1.8.10 and SAM package 1.6.12
- a fresh re-install of the SAM package via IDE did not help

Here the compiler output:

[Serial.write.zip](https://github.com/arduino/ArduinoCore-sam/files/3826998/Serial.write.zip)

Arduino: 1.8.10 (Linux), Board: "Arduino Due (Programming Port)"

/opt/arduino-1.8.10/arduino-builder -dump-prefs -logger=machine -hardware /opt/arduino-1.8.10/hardware -hardware /home/georg/.arduino15/packages -tools /opt/arduino-1.8.10/tools-builder -tools /opt/arduino-1.8.10/hardware/tools/avr -tools /home/georg/.arduino15/packages -built-in-libraries /opt/arduino-1.8.10/libraries -libraries /home/georg/Dokumente/Arduino/libraries -fqbn=arduino:sam:arduino_due_x_dbg -vid-pid=0X2341_0X003D -ide-version=10810 -build-path /tmp/arduino_build_862278 -warnings=none -build-cache /tmp/arduino_cache_314170 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.bossac.path=/home/georg/.arduino15/packages/arduino/tools/bossac/1.6.1-arduino -prefs=runtime.tools.bossac-1.6.1-arduino.path=/home/georg/.arduino15/packages/arduino/tools/bossac/1.6.1-arduino -prefs=runtime.tools.arm-none-eabi-gcc.path=/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1 -prefs=runtime.tools.arm-none-eabi-gcc-4.8.3-2014q1.path=/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1 -verbose /home/georg/Schreibtisch/Serial.write/Serial.write.ino
/opt/arduino-1.8.10/arduino-builder -compile -logger=machine -hardware /opt/arduino-1.8.10/hardware -hardware /home/georg/.arduino15/packages -tools /opt/arduino-1.8.10/tools-builder -tools /opt/arduino-1.8.10/hardware/tools/avr -tools /home/georg/.arduino15/packages -built-in-libraries /opt/arduino-1.8.10/libraries -libraries /home/georg/Dokumente/Arduino/libraries -fqbn=arduino:sam:arduino_due_x_dbg -vid-pid=0X2341_0X003D -ide-version=10810 -build-path /tmp/arduino_build_862278 -warnings=none -build-cache /tmp/arduino_cache_314170 -prefs=build.warn_data_percentage=75 -prefs=runtime.tools.bossac.path=/home/georg/.arduino15/packages/arduino/tools/bossac/1.6.1-arduino -prefs=runtime.tools.bossac-1.6.1-arduino.path=/home/georg/.arduino15/packages/arduino/tools/bossac/1.6.1-arduino -prefs=runtime.tools.arm-none-eabi-gcc.path=/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1 -prefs=runtime.tools.arm-none-eabi-gcc-4.8.3-2014q1.path=/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1 -verbose /home/georg/Schreibtisch/Serial.write/Serial.write.ino
Using board 'arduino_due_x_dbg' from platform in folder: /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12
Using core 'arduino' from platform in folder: /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12
Detecting libraries used...
/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1/bin/arm-none-eabi-g++ -c -g -Os -w -std=gnu++11 -ffunction-sections -fdata-sections -nostdlib -fno-threadsafe-statics --param max-inline-insns-single=500 -fno-rtti -fno-exceptions -w -x c++ -E -CC -mcpu=cortex-m3 -mthumb -DF_CPU=84000000L -DARDUINO=10810 -DARDUINO_SAM_DUE -DARDUINO_ARCH_SAM -D__SAM3X8E__ -mthumb -DUSB_VID=0x2341 -DUSB_PID=0x003e -DUSBCON "-DUSB_MANUFACTURER=\"Arduino LLC\"" "-DUSB_PRODUCT=\"Arduino Due\"" -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/libsam -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/CMSIS/CMSIS/Include/ -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/CMSIS/Device/ATMEL/ -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/variants/arduino_due_x /tmp/arduino_build_862278/sketch/Serial.write.ino.cpp -o /dev/null
Generating function prototypes...
/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1/bin/arm-none-eabi-g++ -c -g -Os -w -std=gnu++11 -ffunction-sections -fdata-sections -nostdlib -fno-threadsafe-statics --param max-inline-insns-single=500 -fno-rtti -fno-exceptions -w -x c++ -E -CC -mcpu=cortex-m3 -mthumb -DF_CPU=84000000L -DARDUINO=10810 -DARDUINO_SAM_DUE -DARDUINO_ARCH_SAM -D__SAM3X8E__ -mthumb -DUSB_VID=0x2341 -DUSB_PID=0x003e -DUSBCON "-DUSB_MANUFACTURER=\"Arduino LLC\"" "-DUSB_PRODUCT=\"Arduino Due\"" -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/libsam -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/CMSIS/CMSIS/Include/ -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/CMSIS/Device/ATMEL/ -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/variants/arduino_due_x /tmp/arduino_build_862278/sketch/Serial.write.ino.cpp -o /tmp/arduino_build_862278/preproc/ctags_target_for_gcc_minus_e.cpp
/opt/arduino-1.8.10/tools-builder/ctags/5.8-arduino11/ctags -u --language-force=c++ -f - --c++-kinds=svpf --fields=KSTtzns --line-directives /tmp/arduino_build_862278/preproc/ctags_target_for_gcc_minus_e.cpp
Sketch wird kompiliert...
/home/georg/.arduino15/packages/arduino/tools/arm-none-eabi-gcc/4.8.3-2014q1/bin/arm-none-eabi-g++ -c -g -Os -w -std=gnu++11 -ffunction-sections -fdata-sections -nostdlib -fno-threadsafe-statics --param max-inline-insns-single=500 -fno-rtti -fno-exceptions -MMD -mcpu=cortex-m3 -mthumb -DF_CPU=84000000L -DARDUINO=10810 -DARDUINO_SAM_DUE -DARDUINO_ARCH_SAM -D__SAM3X8E__ -mthumb -DUSB_VID=0x2341 -DUSB_PID=0x003e -DUSBCON "-DUSB_MANUFACTURER=\"Arduino LLC\"" "-DUSB_PRODUCT=\"Arduino Due\"" -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/libsam -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/CMSIS/CMSIS/Include/ -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/system/CMSIS/Device/ATMEL/ -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino -I/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/variants/arduino_due_x /tmp/arduino_build_862278/sketch/Serial.write.ino.cpp -o /tmp/arduino_build_862278/sketch/Serial.write.ino.cpp.o
/home/georg/Schreibtisch/Serial.write/Serial.write.ino: In function 'void loop()':
Serial.write:8:20: error: call of overloaded 'write(int)' is ambiguous
Serial.write(0x00); // fails
^
/home/georg/Schreibtisch/Serial.write/Serial.write.ino:8:20: note: candidates are:
In file included from /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/variants/arduino_due_x/variant.h:38:0,
from /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino/Arduino.h:201,
from /tmp/arduino_build_862278/sketch/Serial.write.ino.cpp:1:
/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino/UARTClass.h:55:12: note: virtual size_t UARTClass::write(uint8_t)
size_t write(const uint8_t c);
^
In file included from /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino/Stream.h:26:0,
from /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino/HardwareSerial.h:24,
from /home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino/Arduino.h:195,
from /tmp/arduino_build_862278/sketch/Serial.write.ino.cpp:1:
/home/georg/.arduino15/packages/arduino/hardware/sam/1.6.12/cores/arduino/Print.h:49:12: note: size_t Print::write(const char*)
size_t write(const char *str) {
^
exit status 1
call of overloaded 'write(int)' is ambiguous

Reproduce the Due compile failure with the attached Serial.write example, then read cores/arduino/UARTClass.h and cores/arduino/Print.h where the competing write overloads are shown. Confirm that the literal 0x00 compiles while preserving the existing variable case, and verify the result with the Arduino Due build.

Written by the indexing model from the issue text.