Lots of other files use that function and don't have those directives either, e.g. testsuite/special_functions/18_riemann_zeta/compile.cc

Is that also failing?

Could you attach or send me preprocessed source for the failing test?

On 01/19/2016 10:19 PM, thopre01 at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69371
>
>              Bug ID: 69371
>             Summary: UNRESOLVED:
>                      special_functions/18_riemann_zeta/check_value.cc
>                      compilation failed to produce executable
>             Product: gcc
>             Version: 6.0
>              Status: UNCONFIRMED
>            Severity: normal
>            Priority: P3
>           Component: testsuite
>            Assignee: unassigned at gcc dot gnu.org
>            Reporter: thopre01 at gcc dot gnu.org
>                  CC: 3dw4rd at verizon dot net, CaptainSifff at gmx dot de,
>                      redi at gcc dot gnu.org
>    Target Milestone: ---
>              Target: arm-none-eabi
>
> Hi,
>
> special_functions/18_riemann_zeta/check_value.cc fails to build on
> arm-none-eabi targets with the following error:
>
> libstdc++-v3/testsuite/special_functions/18_riemann_zeta/check_value.cc: In
> function 'void test(const testcase_riemann_zeta<Tp> (&)[Num], Tp)':
> libstdc++-v3/testsuite/special_functions/18_riemann_zeta/check_value.cc:285:15:
> error: 'riemann_zeta' is not a member of 'std'
>
> Since special_functions/18_riemann_zeta/check_nan.cc builds successfully, I
> suppose that's due to missing one or all of the following directives:
>
> // { dg-require-c-std "" }
> // { dg-add-options ieee }
>
> which are present for check_nan.cc but not for check_value.cc
>
I would expect that the whole special function test suite would fail.
I do remember we had a timeout issue with riemann zeta on some targets.

The message looks more like a header - cmath - is not included or that 
the line
// { dg-options "-D__STDCPP_WANT_MATH_SPEC_FUNCS__" }
or equivalent is not set.

But my fresh checkout has the necessary things..

(In reply to Ed Smith-Rowland from comment #2)
> The message looks more like a header - cmath - is not included or that 
> the line
> // { dg-options "-D__STDCPP_WANT_MATH_SPEC_FUNCS__" }
> or equivalent is not set.
> 
> But my fresh checkout has the necessary things..

Yes, I wondered if including <limits> first was somehow preventing the extra bits of <cmath> being included but it looks OK to me.

Preprocessed source will tell us what's happening.

Doh, I should have caught that earlier. The bug can be seen in:

% grep -c dg-option special_functions/18_riemann_zeta/check_value.cc
3

Using dg-additional-option for the timeout solves the issue. Maybe the patch could also remove the redundant timeout adjustment in the testcase?

On 01/20/2016 11:46 PM, thopre01 at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69371
>
> --- Comment #4 from Thomas Preud'homme <thopre01 at gcc dot gnu.org> ---
> Doh, I should have caught that earlier. The bug can be seen in:
>
> % grep -c dg-option special_functions/18_riemann_zeta/check_value.cc
> 3
>
> Using dg-additional-option for the timeout solves the issue. Maybe the patch
> could also remove the redundant timeout adjustment in the testcase?
>
I'll take care of that.
My deja-fu is wobbly...

Confirmed, and also seen on aarch64-none-elf and aarch64_be-none-elf.

Fixed as of r233391.