Found the following significant warnings:
  gcx.c:1498:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  gcx.c:1507:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:165:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:179:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:264:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:343:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:497:9: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:486:5: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:464:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:617:7: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:611:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:813:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:814:4: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:1055:7: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:1049:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:1179:8: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:1180:8: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  makeped_c.c:1411:3: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  mia.c:57:7: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  mia.c:99:9: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  mia.c:200:9: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  mia.c:245:9: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:195:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:202:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:205:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:207:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:210:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:435:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:442:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:445:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:447:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
  pgc_c.c:450:1: warning: ignoring return value of function declared with 'warn_unused_result' attribute [-Wunused-result]
See '/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/gap.Rcheck/00install.out' for details.