On OpenBSD 7.4/x86_64, with
  CC="cc -ferror-limit=0"
  CXX="c++ -ferror-limit=0"
I see 4 test failures in "make check":

$ grep ^FAIL: test-suite.log 
FAIL: t/objcxx-minidemo
FAIL: t/objcxx-deps
FAIL: t/strip2
FAIL: t/yacc-mix-c-cxx