Add support for a ".file 0" directive if supporting DWARF 5 or higher.

	PR 25614
	* dwarf2dbg.c (dwarf2_directive_filename): Allow a file number of
	0 if the dwarf_level is 5 or more.  Complain if a filename follows
	a file 0.
	* testsuite/gas/elf/dwarf-5-file0.s: New test.
	* testsuite/gas/elf/dwarf-5-file0.d: New test driver.
	* testsuite/gas/elf/elf.exp: Run the new test.

	PR 25612
	* config/tc-ia64.h (DWARF2_VERISION): Fix typo.
	* doc/as.texi: Fix another typo.

1 files changed, 16 insertions, 6 deletions

diff --git a/gas/dwarf2dbg.c b/gas/dwarf2dbg.c
index 7384a17c577..181401300e6 100644
--- a/gas/dwarf2dbg.c
+++ b/gas/dwarf2dbg.c
@@ -794,17 +794,27 @@ dwarf2_directive_filename (void)
     }
 
   num = get_absolute_expression ();
-  filename = demand_copy_C_string (&filename_len);
-  if (filename == NULL)
-    return NULL;
-  demand_empty_rest_of_line ();
 
-  if ((offsetT) num < 1)
+  if ((offsetT) num < 1 && dwarf_level < 5)
     {
       as_bad (_("file number less than one"));
+      ignore_rest_of_line ();
       return NULL;
     }
 
+  if (num == 0)
+    {
+      demand_empty_rest_of_line ();
+      return NULL;
+    }
+
+  filename = demand_copy_C_string (&filename_len);
+  if (filename == NULL)
+    /* demand_copy_C_string will have already generated an error message.  */
+    return NULL;
+
+  demand_empty_rest_of_line ();
+
   /* A .file directive implies compiler generated debug information is
      being supplied.  Turn off gas generated debug info.  */
   debug_type = DEBUG_NONE;
@@ -821,7 +831,7 @@ dwarf2_directive_filename (void)
       return NULL;
     }
 
-  get_filenum (filename, (unsigned int) num);
+  (void) get_filenum (filename, (unsigned int) num);
 
   return filename;
 }