Note: This report doesn't use the FreeBSD system GCC compiler; it uses an
original GCC 4.3.0 snapshot built and installed separately. However, the bug
also persists in GCC 3.4.6 found in FreeBSD, and in original GCC 4.2.0.
The complete test.c program:
struct foo {
char *p;
int i;
} bar = {
#ifdef BUG
.p = (char[]){"abc"}
#else
.p = "abc"
#endif
};
I.e., it will use a plain string to initialize bar.p if BUG is undefined,
but it will use a compound literal if BUG is defined.
The attempts to compile it (blank lines added for clarity):
$gcc43 -v
Using built-in specs.
Target: i386-portbld-freebsd7.0
Configured with: ./..//gcc-4.3-20061125/configure --disable-nls
--with-system-zlib --with-libiconv-prefix=/usr/local --with-gmp=/usr/local
--program-suffix=43 --libdir=/usr/local/lib/gcc-4.3.0
--with-gxx-include-dir=/usr/local/lib/gcc-4.3.0/include/c++/
--infodir=/usr/local/info/gcc43 --disable-rpath --prefix=/usr/local
i386-portbld-freebsd7.0
Thread model: posix
gcc version 4.3.0 20061125 (experimental)
$gcc43 -Wall -W -Werror -c test.c
$gcc43 -DBUG -Wall -W -Werror -c test.c
cc1: warnings being treated as errors
test.c:10: warning: missing initializer
test.c:10: warning: (near initialization for 'bar.i')
That is, using a compound literal instead of a plain string
to initialize bar.p leads to a warning on a different structure
member, bar.i.
AFAIK GCC would issue such a warning if an old-style structure
initializer were used and not all its members were specified.
However, the example program uses a C99 structure initializer,
and GCC is happy about it unless the compound literal is there
(see the successful compilation when BUG wasn't defined.)
Although it's just a warning, it can be painful for projects
that enforce -Werror policy for their code.
Thanks a lot!
--
Summary: Compound literal in structure initializer causes
irrelevant warning
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: yar at bsd dot chem dot msu dot ru
GCC build triplet: i386-portbld-freebsd7.0
GCC host triplet: i386-portbld-freebsd7.0
GCC target triplet: i386-portbld-freebsd7.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30006
