[Bug c++/106729] New: Missing diagnostic for violation of 9.2.8.5

[Bug c++/106729] New: Missing diagnostic for violation of 9.2.8.5

[whh8b at obs dot cr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106729

            Bug ID: 106729
           Summary: Missing diagnostic for violation of 9.2.8.5
           Product: gcc
           Version: 12.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: whh8b at obs dot cr
  Target Milestone: ---

According to 9.2.8.5 of the C++ standard, the following code should produce a
diagnostic:

void testing() {
    return;
}

inline void testing();

int main() {
    return 0;
}

I can confirm that clang++ v 14.0.0 produces the proper diagnostic.

[Bug c++/106729] Missing diagnostic for violation of 9.2.8.5

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106729

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Will Hawkins from comment #0)
> According to 9.2.8.5 of the C++ standard,

The subclause numbers change with each revision of the standard, so although
"the C++ standard" is currently unambigously C++20, it's more helpful to state
which revision you're referring to, or use the stable tags. In C++20 9.2.8/5 is
[dcl.inline]/5, which says:

"If a definition of a function or variable is reachable at the point of its
first declaration as inline, the program is ill-formed."

This rule first appeared in C++11, added by <https://wg21.link/cwg317>, and we
already have a bug for that: PR 66995

*** This bug has been marked as a duplicate of bug 66995 ***

[Bug c++/106729] Missing diagnostic for violation of 9.2.8.5

[whh8b at obs dot cr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106729

--- Comment #2 from Will Hawkins <whh8b at obs dot cr> ---
Thanks for the feedback, Jonathan. Sorry for the duplicate.

Will