[Dune] Problem with latest dune-common / strangy error message with quadmath.hh

[Christoph Grüninger]

Hi Benedikt,
I have no idea. quadmath.hh remains unchanged for over three years.

1. Have you checked that the standard library is matching your compiler? 
Using GCC I would expect you are linking to libstdc++ and not Clang's 
libc++, right?
2. Given C++23 introduced std::float128_t, we might want to update 
quadmath.hh to use the standard type when available.
Maybe the internal change to support the standard type for C++23 changed 
something? We defined a float128_t in our Impl namespace in quadmath.hh:32.

Kind regards,
Christoph


Am 08.12.25 um 18:48 schrieb Benedikt Oswald:
> Dear Dune,
> 
> using the latest dune git versions, I encounter this error:
> 
> ----------------------
> 
> /Users/oswald/gitwork-demokritos3d/demokritos3d/demokritos3d-dune- 
> bleeding-edge/dune-common/dune/common/quadmath.hh: At global scope:
> /Users/oswald/gitwork-demokritos3d/demokritos3d/demokritos3d-dune- 
> bleeding-edge/dune-common/dune/common/quadmath.hh:318:21: error: 
> expected initializer before '&' token
>    318 |     inline Float128 fma(const Float128& t, const Float128& u, 
> const Float128& v)
> --------------
> 
> 
> Now, I have another code which uses quadrature & compiles well & even 
> links, which rather suggests this is my fault.
> 
> 
> I use:
> 
> Mac OS X, 15.7.1 (24G231)
> 
> gcc 15.1
> 
> and this gcc flag: -fext-numeric-literals
> 
> 
> But still, if you have a suggestion, I am grateful,
> 
> thanks & greetings, Benedikt
> 
> 
> 
> 
>             LSPR AG
>             Dr. sc. techn. Benedikt Oswald
>             Founder, CTO
>             
Kriesbachstrasse 3b
>             CH 8304 Wallisellen
>             
+41 43 366 90 74
>             benedikt.oswald at lspr.swiss
>             www.lspr.swiss <https://lspr.swiss>
> 
> 
> 
> 
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