https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68272
Bug ID: 68272
Summary: Unwanted out-of-line instances for C inline functions
that are also GCC builtins.
Product: gcc
Version: 4.9.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: sorganov at gmail dot com
Target Milestone: ---
When compiling C code, GCC generates out-of-line copy of any inline function
that also happens to be a GCC builtin, in every compilation unit that gets
inline definition, resulting in link errors (see a test-case below).
This violates C standard, as according to the standard, an out-of-line copy of
inline function should only be put in those compilation unit(s) where the
function is declared 'extern' as well.
To reproduce (notice no 'extern' declaration ever):
$ cat inl.h
inline int abs(int i) { return (i >= 0) ? i : -i; }
$ cat a.c
#include "inl.h"
int main() { return 1; }
$ cat b.c
#include "inl.h"
$ gcc a.c b.c
/tmp/ccyZFKSx.o: In function `abs':
b.c:(.text+0x0): multiple definition of `abs'
/tmp/ccijz638.o:a.c:(.text+0x0): first defined here
collect2: error: ld returned 1 exit status
$ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/i586-linux-gnu/4.9/lto-wrapper
Target: i586-linux-gnu
Configured with: [...]
Thread model: posix
gcc version 4.9.2 (Debian 4.9.2-10)
$
