[R-SIG-Mac] gfortran and macos 27

[Peter Dalgaard]

Hi Erich, long time no see.

This is Apple playing numbers games with their versions combined with gfortran thinking it can get the OS version by subtracting 9 from the kernel version.

In short: To set gfortran back on tracks, add the following to your configuration (using config.site <http://config.site/>, or whichever mechanism you prefer):

FFLAGS=-mmacosx-version-min=26.0

(AFAIR 27.0 also works.)

Also notice that Simon is pushing the development version towards using flang instead of gfortran. See his note from 2026-09-21 on this list.

Best,
Peter

> On 2 Oct 2026, at 12.47, Erich Neuwirth <erich.neuwirth using univie.ac.at> wrote:
> 
> I recently upgraded to MacOS 27 and nw I have problems compiling packages from source needing gfortran.
> 
> I get 
> clang: error: invalid version number in '-mmacosx-version-min=18.0'
> make: *** [qapsim.o] Error 1
> ERROR: compilation failed for package ‘qap’
> 
> I tried with gfortran vetsion 14.0.2 from 
> https://github.com/R-macos/gcc-14-branch/releases/tag/gcc-14.2-darwin-r2.1
> 
> and with Fortran 16.2.0 from home-brew
> 
> Is there a workaround?
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-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
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