[Bug libstdc++/111390] New: 'make check-compile' target is not useful

[Bug libstdc++/111390] New: 'make check-compile' target is not useful

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

            Bug ID: 111390
           Summary: 'make check-compile' target is not useful
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

This makefile target does compilation-only testing, to check that tests can be
built. But there's no parallelism, so it takes ages. Worse, it ignores dejagnu
directives so just runs everything with a default set of options, including the
implicit -std=gnu++17

This means that all C++20 and later tests fail. And any XFAIL tests with
dg-error directives "fail" noisily.

I'm not sure it is useful to keep it.

If we want to do compilation-only testing, I think it would be better to modify
the dejagnu procs so that "do-do run" tests are treated as "dg-do compile".

[Bug libstdc++/111390] 'make check-compile' target is not useful

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

Eric Gallager <egallager at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=103324
                 CC|                            |egallager at gcc dot gnu.org

--- Comment #1 from Eric Gallager <egallager at gcc dot gnu.org> ---
kinda related: bug 103324

(In reply to Jonathan Wakely from comment #0)
> If we want to do compilation-only testing, I think it would be better to
> modify the dejagnu procs so that "dg-do run" tests are treated as "dg-do
> compile".

Yes, I think this solution would be preferable to ripping it out entirely.
Also, it would be useful if such a target were available tree-wide, rather than
just for libstdc++.

[Bug libstdc++/111390] 'make check-compile' target is not useful

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The fact nobody has tried to use it in 10+ years makes me think it's not all
that useful.

[Bug libstdc++/111390] 'make check-compile' target is not useful

[egallager at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

--- Comment #3 from Eric Gallager <egallager at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #2)
> The fact nobody has tried to use it in 10+ years makes me think it's not all
> that useful.

Only reason I haven't tried to use it is because I didn't know it existed; if
it were also available from the top-level Makefile, it would be more
discoverable, and more likely to be used.

[Bug libstdc++/111390] 'make check-compile' target is not useful

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think what you're describing or looking for is something completely
different, which might be useful but is not what is present today.

The libstdc++-v3/scripts/check_compile script cannot be turned into what you're
describing. There's simply no way to get to what you want from a naive shell
script that isn't parallelized, and doesn't understand the dg-* directives in
the tests, and only supports a single -std option for all tests.

What we have today is not useful. A replacement would have to be written from
scratch anyway, so ripping it out entirely has no downside as far as I can see.

[Bug libstdc++/111390] 'make check-compile' target is not useful

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Just to add a compile-only "override" would be useful to do bare testing of
cross compilers where no (or an incomplete) runtime is available to reduce
the amount of noise produced (you still get complaints about missing headers of
course).

Not sure if easily doable across all testsuites though.

I agree not so useful for libstdc++

[Bug libstdc++/111390] libstdc++-v3/scripts/check_compile script is not useful

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|'make check-compile' target |libstdc++-v3/scripts/check_
                   |is not useful               |compile script is not
                   |                            |useful

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I've updated the summary to be clear that this is about the current incarnation
of the libstdc++ feature, which has been broken since the default changed
from-std=gnu++98 to -std=gnu++14 many years ago, or even earlier.

[Bug libstdc++/111390] libstdc++-v3/scripts/check_compile script is not useful

[joseph at codesourcery dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111390

--- Comment #7 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Stubbing out execution of tests can be done with a suitable board file (a 
board file to stub out linking as well is a bit more complicated).

https://gcc.gnu.org/pipermail/gcc/2017-September/224422.html