Fix ICE and improve errors for invalid anonymous structure declarations.

	PR fortran/78277
	* gcc/fortran/decl.c (gfc_match_data_decl): Gracefully handle bad
	anonymous structure declarations.

	PR fortran/78277
	* gcc/testsuite/gfortran.dg/dec_structure_17.f90: New test.

From-SVN: r242058

gcc/fortran/ChangeLog

 2016-11-10  Fritz O. Reese <fritzoreese@gmail.com>
 
+	PR fortran/78277
+	* gcc/fortran/decl.c (gfc_match_data_decl): Gracefully handle bad
+	anonymous structure declarations.
+
+2016-11-10  Fritz O. Reese <fritzoreese@gmail.com>
+
 	* decl.c (get_struct_decl, gfc_match_map, gfc_match_union): Fix
 	whitespace.
 	* interface.c (gfc_compare_union_types): Likewise.

gcc/fortran/decl.c

@@ -4901,7 +4901,28 @@ ok:
     }
 
   if (!gfc_error_flag_test ())
-    gfc_error ("Syntax error in data declaration at %C");
+    {
+      /* An anonymous structure declaration is unambiguous; if we matched one
+	 according to gfc_match_structure_decl, we need to return MATCH_YES
+	 here to avoid confusing the remaining matchers, even if there was an
+	 error during variable_decl.  We must flush any such errors.  Note this
+	 causes the parser to gracefully continue parsing the remaining input
+	 as a structure body, which likely follows.  */
+      if (current_ts.type == BT_DERIVED && current_ts.u.derived
+	  && gfc_fl_struct (current_ts.u.derived->attr.flavor))
+	{
+	  gfc_error_now ("Syntax error in anonymous structure declaration"
+			 " at %C");
+	  /* Skip the bad variable_decl and line up for the start of the
+	     structure body.  */
+	  gfc_error_recovery ();
+	  m = MATCH_YES;
+	  goto cleanup;
+	}
+
+      gfc_error ("Syntax error in data declaration at %C");
+    }
+
   m = MATCH_ERROR;
 
   gfc_free_data_all (gfc_current_ns);

gcc/testsuite/ChangeLog

+2016-11-10  Fritz O. Reese <fritzoreese@gmail.com>
+
+	PR fortran/78277
+	* gfortran.dg/dec_structure_17.f90: New test.
+
 2016-11-10  Michael Meissner  <meissner@linux.vnet.ibm.com>
 
 	* gcc.target/powerpc/vsx-qimode.c: New test for QImode, HImode

gcc/testsuite/gfortran.dg/dec_structure_17.f90

+! { dg-do compile }
+! { dg-options "-fdec-structure" }
+!
+! PR fortran/78277
+!
+! Fix ICE for invalid structure declaration code.
+!
+
+subroutine sub1()
+  structure /s/
+    structure t
+      integer i
+    end structure
+  end structure
+  record /s/ u
+  interface
+    subroutine sub0(u)
+      structure /s/
+        structure t. ! { dg-error "Syntax error in anonymous structure decl" }
+          integer i
+        end structure
+      end structure
+      record /s/ u
+    end
+  end interface
+  call sub0(u)
+end