MSP430FR2355: DWARF error: line info data is bigger (0xfffffffc) than the space remaining in the section (0x50)

There has to be more. For one, warnings.

Usually you would include a function prototype of init() in init.h to keep the compiler from whining.

But only listing main.o on the OBJECTS line of your makefile means that init.c isn't going to be compiled or linked. So init() will be missing and the linker should be complaining about that.

You can try to modify the init.h as below

#ifndef ESM_H_
#define ESM_H_

void init(void);

#endif /* ESM_H_ */

Apologies for that. Of course you are correct. My mistake. I am having prototypes in the init.h in my other program, just forgot it for this example. 

However, unfortunately it doesn't solve the problem. Here is the full output:

sage@fedora:~/workspace/fwTesting$ make
/opt/ti/msp430-gcc/bin/msp430-elf-gcc -I /opt/ti/msp430-gcc/include -I. -mmcu=MSP430FR2355 -ffunction-sections -fdata-sections -Og -Wall -g -DDEPRECATED -v -L /opt/ti/msp430-gcc/include -Wl,-Map,main.map,--gc-sections main.o -o MSP430FR2355.out
Using built-in specs.
COLLECT_GCC=/opt/ti/msp430-gcc/bin/msp430-elf-gcc
COLLECT_LTO_WRAPPER=/opt/ti/msp430-gcc/bin/../libexec/gcc/msp430-elf/9.3.1/lto-wrapper
Target: msp430-elf
Configured with: ../../gcc/configure --target=msp430-elf --enable-languages=c,c++ --disable-nls --enable-initfini-array --build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu --enable-target-optspace --enable-newlib-nano-formatted-io --with-pkgversion='Mitto Systems Limited - msp430-gcc 9.3.1.11'
Thread model: single
gcc version 9.3.1 (Mitto Systems Limited - msp430-gcc 9.3.1.11)
COMPILER_PATH=/opt/ti/msp430-gcc/bin/../libexec/gcc/msp430-elf/9.3.1/:/opt/ti/msp430-gcc/bin/../libexec/gcc/:/opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/../../../../msp430-elf/bin/
LIBRARY_PATH=/opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/:/opt/ti/msp430-gcc/bin/../lib/gcc/:/opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/../../../../msp430-elf/lib/
COLLECT_GCC_OPTIONS='-I' '/opt/ti/msp430-gcc/include' '-I' '.' '-mmcu=msp430fr2355' '-ffunction-sections' '-fdata-sections' '-Og' '-Wall' '-g' '-D' 'DEPRECATED' '-v' '-L/opt/ti/msp430-gcc/include' '-o' 'MSP430FR2355.out' '-mdevices-csv-loc=/opt/ti/msp430-gcc/include/devices.csv' '-mdevices-csv-loc=/opt/ti/msp430-gcc/include/devices.csv' '-mcpu=msp430xv2'
/opt/ti/msp430-gcc/bin/../libexec/gcc/msp430-elf/9.3.1/collect2 -plugin /opt/ti/msp430-gcc/bin/../libexec/gcc/msp430-elf/9.3.1/liblto_plugin.so -plugin-opt=/opt/ti/msp430-gcc/bin/../libexec/gcc/msp430-elf/9.3.1/lto-wrapper -plugin-opt=-fresolution=/tmp/ccQRlE87.res -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lmul_f5 -plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgcc -plugin-opt=-pass-through=-lcrt -plugin-opt=-pass-through=-lnosys -plugin-opt=-pass-through=-lgcc -o MSP430FR2355.out /opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/../../../../msp430-elf/lib/crt0.o /opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/crtbegin_no_eh.o -L/opt/ti/msp430-gcc/include -L/opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1 -L/opt/ti/msp430-gcc/bin/../lib/gcc -L/opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/../../../../msp430-elf/lib -Map main.map --gc-sections main.o -lgcc --start-group -lmul_f5 -lc -lgcc -lcrt -lnosys --end-group --script=msp430fr2355.ld -lgcc /opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/crtend_no_eh.o -lgcc
/opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/../../../../msp430-elf/bin/ld: /opt/ti/msp430-gcc/bin/../lib/gcc/msp430-elf/9.3.1/../../../../msp430-elf/bin/ld: DWARF error: line info data is bigger (0xfffffffc) than the space remaining in the section (0x50)
main.o: in function `.Loc.8.1':
main.c:(.text.main+0x8): undefined reference to `init'
collect2: error: ld returned 1 exit status
make: *** [Makefile:20: MSP430FR2355.out] Error 1
sage@fedora:~/workspace/fwTesting$

Focused on the warning and paid no attention to the error:

"main.c:(.text.main+0x8): undefined reference to `init'"

My assumption is that the undefined reference to `init' is caused by the DWARF error. The linker stops linking right there. (Which we still have no clue why this DWARF error is happening). I found something about an older bug: sourceware.org/.../show_bug.cgi

As a bug fix, the modification of the linker-script of the particular MSP430 (in my case msp430fr2355.ld) is proposed:

  .debug_line     0 : { *(.debug_line) }

(It is probably near the end of the script).  Replace it with this line:

  .debug_line     0 : { *(.debug_line .debug_line.* .debug_line_end ) }

But in my linker script, its already like the lower line, so this had been fixed. 
Now I am running out of ideas...

OBJECTS = main.o init.o did the job.

Thank you so much David! I was indeed blinded by that weird DWARF error.