On 1/29/20 10:01 AM, Darrick J. Wong wrote: > On Wed, Jan 29, 2020 at 09:16:58AM -0600, Eric Sandeen wrote: >> In each of these cases, db, logprint, and mdrestore are redeclaring >> as a global variable something which was already provided by a >> library they link with. >> >> gcc now defaults to -fno-common and trips over these global variables >> which are declared in utilities as well as in libxfs and libxlog, and >> it causes the build to fail. >> >> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx> >> --- ... >> + print_exit = 1; /* -e is now default. specify -c to override */ > > With the trailing whitespace after the comment fixed, oh burn. ;) > Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx> > > Though given your earlier comment on IRC, maybe we should investigate > why -fno-common would be useful (since Fedora turned it on??) or if it > should be in the regular build to catch multiply defined global vars? That's a good idea. FWIW my understanding is that it's a new default in gcc10. Docs say w.r.t. -fcommon: "This behavior is inconsistent with C++, and on many targets implies a speed and code size penalty on global variable references. It is mainly useful to enable legacy code to link without errors." Want me to send a V3 w/ -fno-common explicitly set? -Eric
