On Mon, Jan 9, 2012 at 21:21, Tobias Burnus <bur...@net-b.de> wrote: > Hello, > > in GCC 4.6, gfortran printed before the backtrace, e.g., > Program received signal 8 (SIGFPE): Floating-point exception. > to STDERR followed by the backtrace. > > This was done by registering an error handler and - finishing with a > sys_exit(5). Since 4.7 with the patch for PR 48915 (comment 3) [1], GCC does > no longer print this line but just a simple: > A fatal error occurred! Backtrace for this error: > followed by the the backtrace. It then raises the signal via the default > handler. (The system might then print more information, e.g. "Floating point > exception (core dumped)", which might end up on STDOUT contrary to the > backtrace which goes to STDERR.) > > [1] Cf. runtime/compile_options.c at > http://gcc.gnu.org/viewcvs?view=revision&revision=173750 > > The attached patch by Harald Anlauf (cf. PR, minutely modified by me) > restores GCC 4.6's printing of the signal number by simply printing this > information before the back trace. (Copyright wise, the patch is simple even > as it exceeds ten lines: it mostly undoes part of Rev. 173750 [1].) > > With the patch, one can get (cf. PR) an output to STDERR like: > > Program received signal 8 (SIGFPE): Floating-point exception. > > Backtrace for this error: > #0 0x805891F in _gfortrani_show_backtrace at backtrace.c:261 > #1 0x804951F in _gfortrani_backtrace_handler at compile_options.c:93 > #2 0xFFFFE3FF > #3 0x80493B3 in foo at gfcbug113.f90:8 > #4 0x804940B in backtrace at gfcbug113.f90:3 > > > which might be followed by the OS diagnostic, e.g. on Linux with a Bash one > gets the following to STDOUT: > > Floating point exception (core dumped) > > > OK for the trunk?
I see this was already Ok'ed, but still a few comments: - The integer values for the signal numbers are not standardized, hence printing them might give the user a false impression that these numbers convey some information beyond whichever SIG* macro they map to on that particular target. - It doesn't test all the signals which are actually handled, see compile_options.c:set_options(). Also, as a minor point, there's no need to have #ifdef tests for the C89 signals, again see set_options(). - The floor is now open for some enterprising person to file a bug complaining that duplicate information is printed when, as usual, stdout and stderr are output to the same device. ;-) -- Janne Blomqvist
