Fortran : ICE in build_field PR95614

Fortran  :  ICE in build_field PR95614

Local identifiers can not be the same as a module name.  Original
patch by Steve Kargl resulted in name clashes between common block
names and local identifiers.  A local identifier can be the same as
a global identier if that identifier is not a module or a program.
The original patch was modified to reject global identifiers that
represent a module or a program.

2020-10-14  Steven G. Kargl  <kargl@gcc.gnu.org>
	    Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/fortran/ChangeLog:

	PR fortran/95614
	* decl.c (gfc_get_common): Use gfc_match_common_name instead
	of match_common_name.
	* decl.c (gfc_bind_idents): Use gfc_match_common_name instead
	of match_common_name.
	* match.c : Rename match_common_name to gfc_match_common_name.
	* match.c (gfc_match_common): Use gfc_match_common_name instead
	of match_common_name.
	* match.h : Rename match_common_name to gfc_match_common_name.
	* resolve.c (resolve_common_vars): Check each symbol in a
	common block has a global symbol.  If there is a global symbol
	issue an error if the symbol type is a module or a program.

2020-10-14  Mark Eggleston  <markeggleston@gcc.gnu.org>

gcc/testsuite/ChangeLog:

	PR fortran/95614
	* gfortran.dg/pr95614_1.f90: New test.
	* gfortran.dg/pr95614_2.f90: New test.
	* gfortran.dg/pr95614_3.f90: New test.
	* gfortran.dg/pr95614_4.f90: New test.