[Rd] Build error with gcc 15

[Prof Brian Ripley]

On 15/01/2025 16:06, Iñaki Ucar wrote:
> Dear R Core,
> 
> GCC 15 is already in Fedora rawhide, because it will be part of the next
> release, Fedora 42. R 4.4.2 fails to build with the following error [1]:
> 
>> sys-std.c:1189:1: warning: ‘noreturn’ attribute ignored [-Wattributes]
>>   1189 | void Rstd_CleanUp(SA_TYPE saveact, int status, int runLast)
>>        | ^~~~
>> sys-std.c:1189:1: error: expected identifier or ‘(’ before ‘void’

You failed to say that GCC 15 defaults to C23 (and they have not yet 
documented that).
> 
> I've seen some references to this in the source code, so this may be fixed
> in R devel. If this is the case, it would be great if you could provide a
> patch that I can apply to v4.4.2 until the next R release (or maybe I
> should just specify an older C standard?).

Look at the definition of NORET in R_ext/Error.h.  You want r87411;

r87411 | ripley | 2024-12-01 10:11:10 +0000 (Sun, 01 Dec 2024) | 1 line

gcc pre-15 does not yet support [[noreturn]]

GCC 15 is not even at RC stage, and this is one of many undocumented 
changes -- so they have not even got to the documentation-fixing stage. 
This is a GCC issue -- both LLVM and Apple clang build R-patched in C23 
mode.

We will port this to R-patched, unless GCC 15 is fixed before its or 
R-patched's release.

-- 
Brian D. Ripley,                  ripley using stats.ox.ac.uk
Emeritus Professor of Applied Statistics, University of Oxford