email from CRAN (BDR):

GCC trunk aka 11.0 is still under development but (because it may need to be used for macOS on ARM) we done a CRAN check run using it. For packages

BayesXsrc Boom CDVine DEploid DataGraph EditImputeCont
OBsMD Rttf2pt1 VineCopula bliss clusternor excursions gdalcubes knor
np pbdSLAP rgl ribiosUtils rlecuyer rmetasim s2 scrm tuneR

(and some others reported separately) it newly reports issues that look worth fixing and are now reported as an 'Additional issue' on the CRAN check pages for these packages. Please review these and fix or let us know if you believe they are gcc bugs.

I don't know how difficult it will be to reproduce these (although in most cases the issue is clear from the report). We compiled gcc from source but some Linux distros have builds available and someone suggested that docker images are available.

[For np I also noticed an unchecked allocation by malloc, which can fail and return NULL.]