[Bug ipa/97945] New: undefined reference err when a function defined inline

[Bug ipa/97945] New: undefined reference err when a function defined inline

[dongjianqiang2 at huawei dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97945

            Bug ID: 97945
           Summary: undefined reference err when a function defined inline
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dongjianqiang2 at huawei dot com
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

$ cat z1.c
#define likely(x) __builtin_expect((x), 1)
#define unlikely(x) __builtin_expect((x), 0)
int a=10;
inline void test() {
 __builtin_puts("hot");
 a++;
 __builtin_puts("hot");
}

void main() {
    __builtin_puts("hot");
    if (unlikely(a==2)) {
      test();
    }
    __builtin_puts("hot");
}

gcc test.c -O2

in function `main':
test.c:(.text.startup+0x38): undefined reference to `test'
collect2: error: ld returned 1 exit status

But succeed when compiling with -fgnu89-inline.

[Bug c/97945] undefined reference err when a function defined inline

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97945

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED
          Component|ipa                         |c
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
That is a user error.
The C99 and later standards mandate this behavior.
Either use static inline, or in one TU you need to use extern inline, or use
the GNU inline semantics.