[Bug c++/54706] New: -fsyntax-only suppresses a compilation error

[Bug c++/54706] New: -fsyntax-only suppresses a compilation error

[dave at boostpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

             Bug #: 54706
           Summary: -fsyntax-only suppresses a compilation error
    Classification: Unclassified
           Product: gcc
           Version: 4.7.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: dave@boostpro.com


Compile the following with -std=c++11 both with and without -fsyntax-only and
note the difference:

template<class...Fs> struct pair;

template<class F1, class...Fs>
struct pair<F1, Fs...> : F1, Fs...
{
    typedef pair type;
};

template<class...Fs>
typename pair<Fs...>::type make(Fs...x)
{ return pair<Fs...>(x...); }

struct X {}; struct Y{};

auto a = make(X(),Y());

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-09-25 15:42:09 UTC ---
As already discussed in another PR, with -fsyntax-only no template
instantiation occurs. Can be that?

In any case, let's add Jason in CC about the instantiation issue, quite a few
people are not so happy about it. Maybe a good occasion to clarify that (very
old, AFAIK) choice...

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-09-25 15:53:24 UTC ---
See PR52964

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[dave at boostpro dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

--- Comment #3 from Dave Abrahams <dave at boostpro dot com> 2012-09-25 19:55:31 UTC ---
(In reply to comment #1)
> As already discussed in another PR, with -fsyntax-only no template
> instantiation occurs. Can be that?

Certainly that explains it.

> In any case, let's add Jason in CC about the instantiation issue, quite a few
> people are not so happy about it. Maybe a good occasion to clarify that (very
> old, AFAIK) choice...

Or change it, or provide another option.  Clang's -fsyntax-only does
instantiate, BTW.

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xinliangli at gmail dot com

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-16 23:08:42 UTC ---
*** Bug 52964 has been marked as a duplicate of this bug. ***

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2014-07-19
           Assignee|unassigned at gcc dot gnu.org      |paolo.carlini at oracle dot com
     Ever confirmed|0                           |1

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Looks like it makes sense to instantiate in GCC too.

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |NEW
           Assignee|paolo.carlini at oracle dot com    |unassigned at gcc dot gnu.org

[Bug c++/54706] -fsyntax-only suppresses a compilation error

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54706

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |6.0
         Resolution|---                         |FIXED

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed in GCC 6+, most likely by r6-1401 which changed slightly how
-fsyntax-only is handled.