Add -fpermissive, but make sure the warning doesn't get supressed

avr/platform.txt

@@ -2,29 +2,29 @@
 # ------------------------------
 
 # For more info:
-# https://github.com/arduino/Arduino/wiki/Arduino-IDE-1.5---3rd-party-Hardware-specification
+# https://arduino.github.io/arduino-cli/latest/platform-specification/
 
 name=MightyCore
 version=2.2.2
 
 # AVR compile variables
 # ---------------------
 
-compiler.warning_flags=-w
+compiler.warning_flags=
 compiler.warning_flags.none=-w
 compiler.warning_flags.default=
 compiler.warning_flags.more=-Wall
 compiler.warning_flags.all=-Wall -Wextra
 
-# Default "compiler.path" is correct, change only if you want to overidde the initial value
+# Default "compiler.path" is correct, change only if you want to override the initial value
 compiler.path={runtime.tools.avr-gcc.path}/bin/
 compiler.c.cmd=avr-gcc
 compiler.c.flags=-c -g -Os {compiler.warning_flags} -std=gnu11 -ffunction-sections -fdata-sections -MMD
 compiler.c.elf.flags={compiler.warning_flags} -Os -Wl,--gc-sections,--section-start=.FAR_MEM1=0x10000
 compiler.c.elf.cmd=avr-gcc
 compiler.S.flags=-c -g -x assembler-with-cpp
 compiler.cpp.cmd=avr-g++
-compiler.cpp.flags=-c -g -Os {compiler.warning_flags} -std=gnu++17 -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD
+compiler.cpp.flags=-c -g -Os {compiler.warning_flags} -std=gnu++17 -fpermissive -fno-exceptions -ffunction-sections -fdata-sections -fno-threadsafe-statics -MMD
 compiler.ar.cmd={ltoarcmd}
 compiler.ar.flags=rcs
 compiler.objcopy.cmd=avr-objcopy
@@ -65,7 +65,6 @@ recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.S.flags} -mmcu={b
 archive_file_path={build.path}/{archive_file}
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"
 
-
 ## Combine gc-sections, archives, and objects
 recipe.c.combine.pattern="{compiler.path}{compiler.c.elf.cmd}" {compiler.c.elf.flags} -mmcu={build.mcu} {compiler.c.elf.extra_flags} -o "{build.path}/{build.project_name}.elf" {object_files} "{build.path}/{archive_file}" "-L{build.path}" -lm
 
@@ -140,9 +139,10 @@ tools.avrdude.bootloader.params.verbose=-v
 tools.avrdude.bootloader.params.quiet=-q -q
 tools.avrdude.bootloader.pattern="{cmd.path}" "-C{config.path}" {bootloader.verbose} -p{build.mcu} -c{protocol} {program.extra_params} "-Uflash:w:{runtime.platform.path}/bootloaders/{bootloader.file}:i" -Ulock:w:{bootloader.lock_bits}:m
 
+tools.avrdude_remote.upload.pattern=/usr/bin/run-avrdude /tmp/sketch.hex {upload.verbose} -p{build.mcu}
 
 # USB Default Flags
-# Default blank usb manufacturer will be filled it at compile time
+# Default blank usb manufacturer will be filled in at compile time
 # - from numeric vendor ID, set to Unknown otherwise
 build.usb_manufacturer="Unknown"
 build.usb_flags=-DUSB_VID={build.vid} -DUSB_PID={build.pid} '-DUSB_MANUFACTURER={build.usb_manufacturer}' '-DUSB_PRODUCT={build.usb_product}'