[Bug testsuite/80661] New: make check-gcc RUNTESTFLAGS="dg.exp=g*" runs all the tests in gcc.dg

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80661

            Bug ID: 80661
           Summary: make check-gcc RUNTESTFLAGS="dg.exp=g*" runs all the
                    tests in gcc.dg
           Product: gcc
           Version: 8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: testsuite
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dominiq at lps dot ens.fr
  Target Milestone: ---

It is my understanding that the command

make check-gcc RUNTESTFLAGS="dg.exp=a*"

runs all the tests in gcc.dg starting with an 'a' (same thing for g++ and
gfortran). AFAICT (on darwin) this is true except when 'a' is replaced with
'g', 'o', or 't' (all the letters tested with gfortran). Is anybody
understanding what is special with these three letters?