https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100464
--- Comment #15 from Chengnian Sun <cnsun at uwaterloo dot ca> --- (In reply to Jakub Jelinek from comment #14) > Yes. You'll get an error, like: > error: t.c: ‘-fcompare-debug’ failure (length) > or > error: t.c: ‘-fcompare-debug’ failure > Under the hood, the driver invokes the compiler once with > the options you've given plus -fdump-final-insns=sometempfile1 > and then also with the options you've given plus -gtoggle > -fcompare-debug-second -fdump-final-insns=sometempfile2 (and will throw away > stdout/stderr from the compiler). The (length) failure means sometempfile1 > and sometempfile2 have different lengths, while the other error mean they > have the same length, but their content differs. Thank you.