https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79695
Bug ID: 79695
Summary: spurious -Wunused-variable on a static global of a
type declared unused
Product: gcc
Version: 7.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: msebor at gcc dot gnu.org
Target Milestone: ---
G++ (but not GCC in C mode) warns on all three variables in the program below
even though their type is declared attribute unused and thus no warning should
be issued for them.
In addition, the wording of the warning is inconsistent. It should be the same
in both cases. The first instance is issued by the C++ front end and the
latter two come from cgraphunit.c.
$ (set -x && cat u.c && for lang in c c++; do gcc -S -Wall -Wextra -Wpedantic
-x$lang u.c; done)
+ cat u.c
typedef int __attribute__ ((unused)) T;
static T x;
void f (void)
{
static T y;
}
void g (void)
{
T z;
}
+ for lang in c c++
+ gcc -S -Wall -Wextra -Wpedantic -xc u.c
+ for lang in c c++
+ gcc -S -Wall -Wextra -Wpedantic -xc++ u.c
u.c: In function ‘void f()’:
u.c:7:12: warning: unused variable ‘y’ [-Wunused-variable]
static T y;
^
u.c: At global scope:
u.c:7:12: warning: ‘y’ defined but not used [-Wunused-variable]
u.c:3:10: warning: ‘x’ defined but not used [-Wunused-variable]
static T x;
^
