Greetings,

Propose patch for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104812 to
reject non-conforming code when construct-name clashes with already
defined symbol names, e.g:

     subroutine s1
       logical :: x
       x: if (x) then ! Currently gfortran accepts 'x' as constuct-name
       end if x
     end
     
Steve Kargl poited that (Fortran 2018, 19.4, p 498):

   Identifiers of entities, other than statement or construct entities (19.4),
   in the classes

     (1) named variables, ..., named constructs, ...,

  Within its scope, a local identifier of one class shall not be the
  same as another local identifier of the same class,
  

Regtested on x86_64-pc-linux-gnu, OK for mainline?

Thanks.