/tmp/ccH8y0fh.o: In function `main':
foo.cc:(.text.startup+0x32): relocation truncated to fit: R_X86_64_PC32 against symbol `a' defined in .bss section in /tmp/ccH8y0fh.o
foo.cc:(.text.startup+0x39): relocation truncated to fit: R_X86_64_PC32 against symbol `a' defined in .bss section in /tmp/ccH8y0fh.o
foo.cc:(.text.startup+0x86): relocation truncated to fit: R_X86_64_PC32 against symbol `a' defined in .bss section in /tmp/ccH8y0fh.o
foo.cc:(.text.startup+0x8d): relocation truncated to fit: R_X86_64_PC32 against symbol `a' defined in .bss section in /tmp/ccH8y0fh.o
foo.cc:(.text.startup+0x94): relocation truncated to fit: R_X86_64_PC32 against symbol `sum' defined in .bss section in /tmp/ccH8y0fh.o
foo.cc:(.text.startup+0xf4): relocation truncated to fit: R_X86_64_PC32 against symbol `sum' defined in .bss section in /tmp/ccH8y0fh.o
/tmp/ccH8y0fh.o: In function `_GLOBAL__sub_I_a':
foo.cc:(.text.startup+0x243): relocation truncated to fit: R_X86_64_PC32 against `.bss'
foo.cc:(.text.startup+0x261): relocation truncated to fit: R_X86_64_PC32 against `.bss'
collect2: error: ld returned 1 exit status