From 898d369f3bc770c0db2ad3973c204e6d11ec0e0f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jan=20Pokorn=C3=BD?= Date: Tue, 21 Jan 2020 18:24:44 +0100 Subject: [PATCH] Build: get ready for implicit -fno-common with upcoming GCC 10 Currently, -fno-common yields (and only yields, slightly restructured): > /usr/bin/ld: > pacemaker_execd-execd_commands.o: > pcmk/daemons/execd/pacemaker-execd.h:23: > multiple definition of `rsc_list'; > + pacemaker_execd-pacemaker-execd.o: > pcmk/daemons/execd/pacemaker-execd.h:23: > first defined here > > pacemaker_execd-execd_alerts.o: > pcmk/daemons/execd/pacemaker-execd.h:23: > multiple definition of `rsc_list'; > + pacemaker_execd-pacemaker-execd.o: > pcmk/daemons/execd/pacemaker-execd.h:23: > first defined here > > collect2: error: ld returned 1 exit status The problem is that a global (with external linkage) variable without explicit "extern" stands for "tentative definition" (as opposed to mere reference to existing object with external linkage otherwise), and these won't get automagically merged in -fno-common case (which is going to be a default in upcoming GCC 10). Solution is to explicitly add "extern" storage-class specifiers at what's indeed meant as non-tentative reference in the header files that are going to be included from various translation units that will end up in the same link. No more attempts at finding these was performed, just the only instance that got hit in practice (see above) receives this treatment, since manual work simply doesn't scale. Either a static analysis can be employed to mark other potential show-stoppers, or we'll just deal with the issues on case-by-case basis (with the gargantuan assistence of CI systems). References: https://gcc.gnu.org/gcc-10/porting_to.html#common --- daemons/execd/pacemaker-execd.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/daemons/execd/pacemaker-execd.h b/daemons/execd/pacemaker-execd.h index 4a52d91834..dab3ccdbee 100644 --- a/daemons/execd/pacemaker-execd.h +++ b/daemons/execd/pacemaker-execd.h @@ -20,7 +20,7 @@ # include # endif -GHashTable *rsc_list; +extern GHashTable *rsc_list; typedef struct lrmd_rsc_s { char *rsc_id;