[Bug fortran/77260] New: bogus warning with ENTRY in a function

["martin at mpa-garching dot mpg dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77260

            Bug ID: 77260
           Summary: bogus warning with ENTRY in a function
           Product: gcc
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: martin@mpa-garching.mpg.de
  Target Milestone: ---

Created attachment 39460
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=39460&action=edit
test case

When compiling the test case below, current trunk gfortran warns about "f2"
being unused:

martin@martin-Latitude-E7450 ~/tmp $ gfortran -std=f2008 -W -Wall entry.f90 
entry.f90:11:8:

 entry f2
        1
Warning: Fortran 2008 obsolescent feature: ENTRY statement at (1)
entry.f90:9:10:

 integer f2
          1
Warning: Unused variable ‘f2’ declared at (1) [-Wunused-variable]

However, if I comment out the "integer f2" statement, gfortran produces an
error (as I would expect):
martin@martin-Latitude-E7450 ~/tmp $ gfortran -std=f2008 -W -Wall entry.f90 
entry.f90:11:8:

 entry f2
        1
Warning: Fortran 2008 obsolescent feature: ENTRY statement at (1)
entry.f90:4:12:

 public f1,f2
            1
Error: Contained function ‘f2’ at (1) has no IMPLICIT type
entry.f90:17:4:

 use foo
    1
Fatal Error: Can't open module file ‘foo.mod’ for reading at (1): No such file
or directory
compilation terminated.

I think the warning is bogus ... the entry somehow must be given an explicit
return type.
This behaviour happens on trunk and 5.4; I haven't tested other branches so
far.