binutils, ld: make objdump --ctf's parameter optional

ld by default (and always, unless adjusted with a hand-rolled linker
script) emits deduplicated CTF into the .ctf section.  But viewing
it needs you to explicitly tell objdump this: it doesn't default
its argument, even though what you always end up typing is
--ctf=.ctf.

This is annoying, so make the argument optional.

binutils/ChangeLog
2021-10-25  Nick Alcock  <nick.alcock@oracle.com>

	* objdump.c (usage): --ctf now has an optional argument.
	(main): Adjust accordingly.
	(dump_ctf): Default it.
	* doc/ctf.options.texi: Adjust.

ld/ChangeLog
2021-10-25  Nick Alcock  <nick.alcock@oracle.com>

	* testsuite/ld-ctf/array.d: Change --ctf=.ctf to --ctf.
	* testsuite/ld-ctf/conflicting-cycle-1.B-1.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-1.B-2.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-1.parent.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-2.A-1.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-2.A-2.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-2.parent.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-3.C-1.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-3.C-2.d: Likewise.
	* testsuite/ld-ctf/conflicting-cycle-3.parent.d: Likewise.
	* testsuite/ld-ctf/conflicting-enums.d: Likewise.
	* testsuite/ld-ctf/conflicting-typedefs.d: Likewise.
	* testsuite/ld-ctf/cross-tu-cyclic-conflicting.d: Likewise.
	* testsuite/ld-ctf/cross-tu-cyclic-nonconflicting.d: Likewise.
	* testsuite/ld-ctf/cross-tu-into-cycle.d: Likewise.
	* testsuite/ld-ctf/cross-tu-noncyclic.d: Likewise.
	* testsuite/ld-ctf/cycle-1.d: Likewise.
	* testsuite/ld-ctf/cycle-2.A.d: Likewise.
	* testsuite/ld-ctf/cycle-2.B.d: Likewise.
	* testsuite/ld-ctf/cycle-2.C.d: Likewise.
	* testsuite/ld-ctf/data-func-conflicted.d: Likewise.
	* testsuite/ld-ctf/diag-cttname-null.d: Likewise.
	* testsuite/ld-ctf/diag-cuname.d: Likewise.
	* testsuite/ld-ctf/diag-parlabel.d: Likewise.
	* testsuite/ld-ctf/enum-forward.d: Likewise.
	* testsuite/ld-ctf/enums.d: Likewise.
	* testsuite/ld-ctf/forward.d: Likewise.
	* testsuite/ld-ctf/function.d: Likewise.
	* testsuite/ld-ctf/nonrepresentable.d: Likewise.
	* testsuite/ld-ctf/slice.d: Likewise.
	* testsuite/ld-ctf/super-sub-cycles.d: Likewise.

3 files changed, 16 insertions, 4 deletions

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index ea9cfe4..efde928 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,5 +1,12 @@
 2021-10-25  Nick Alcock  <nick.alcock@oracle.com>
 
+	* objdump.c (usage): --ctf now has an optional argument.
+	(main): Adjust accordingly.
+	(dump_ctf): Default it.
+	* doc/ctf.options.texi: Adjust.
+
+2021-10-25  Nick Alcock  <nick.alcock@oracle.com>
+
 	* objdump.c (usage): --ctf-parent now takes a name, not a section.
 	(dump_ctf): Don't open a separate section; use the parent_name in
 	ctf_dict_open instead.  Use ctf_archive_next, not ctf_archive_iter,
diff --git a/binutils/doc/ctf.options.texi b/binutils/doc/ctf.options.texi
index 34451f9..2820946 100644
--- a/binutils/doc/ctf.options.texi
+++ b/binutils/doc/ctf.options.texi
@@ -1,13 +1,15 @@
 @c This file contains the entry for the --ctf, --ctf-parent, --ctf-symbols, -and
 @c --ctf-strings options that are common to both readelf and objdump.
 
-@item --ctf=@var{section}
+@item --ctf[=@var{section}]
 @cindex CTF
 @cindex Compact Type Format
 
 Display the contents of the specified CTF section.  CTF sections themselves
 contain many subsections, all of which are displayed in order.
 
+By default, display the name of the section named @var{.ctf}, which is the
+name emitted by @command{ld}.
 
 @item --ctf-parent=@var{member}
 
diff --git a/binutils/objdump.c b/binutils/objdump.c
index 43472e1..356e3ec 100644
--- a/binutils/objdump.c
+++ b/binutils/objdump.c
@@ -273,7 +273,7 @@ usage (FILE *stream, int status)
                             separate debuginfo files.  (Implies -WK)\n"));
 #ifdef ENABLE_LIBCTF
   fprintf (stream, _("\
-      --ctf=SECTION        Display CTF info from SECTION\n"));
+      --ctf[=SECTION]      Display CTF info from SECTION, (default `.ctf')\n"));
 #endif
   fprintf (stream, _("\
   -t, --syms               Display the contents of the symbol table(s)\n"));
@@ -460,7 +460,7 @@ static struct option long_options[]=
   {"include", required_argument, NULL, 'I'},
   {"dwarf", optional_argument, NULL, OPTION_DWARF},
 #ifdef ENABLE_LIBCTF
-  {"ctf", required_argument, NULL, OPTION_CTF},
+  {"ctf", optional_argument, NULL, OPTION_CTF},
   {"ctf-parent", required_argument, NULL, OPTION_CTF_PARENT},
 #endif
   {"stabs", no_argument, NULL, 'G'},
@@ -4218,6 +4218,8 @@ dump_ctf (bfd *abfd, const char *sect_name, const char *parent_name)
   size_t member = 0;
   int err;
 
+  if (sect_name == NULL)
+    sect_name = ".ctf";
 
   if ((ctfdata = read_section_stabs (abfd, sect_name, &ctfsize, NULL)) == NULL)
       bfd_fatal (bfd_get_filename (abfd));
@@ -5449,7 +5451,8 @@ main (int argc, char **argv)
 #ifdef ENABLE_LIBCTF
 	case OPTION_CTF:
 	  dump_ctf_section_info = true;
-	  dump_ctf_section_name = xstrdup (optarg);
+	  if (optarg)
+	    dump_ctf_section_name = xstrdup (optarg);
 	  seenflag = true;
 	  break;
 	case OPTION_CTF_PARENT: