as: Reject unknown -gXXX option

	* as.c (parse_args): Reject unknown -gXXX option.
	* testsuite/gas/all/empty.s: New file.
	* testsuite/gas/all/pr29067.d: Likewise.
	* testsuite/gas/all/pr29067.err: Likewise.
	* testsuite/gas/all/gas.exp: Run pr29067.

gas/as.c

diff --git a/gas/as.c b/gas/as.c
index f320bac..0262a6f 100644
--- a/gas/as.c
+++ b/gas/as.c
@@ -836,6 +836,8 @@
 	     versions/sections/options.  */
 	  if (startswith (old_argv[optind - 1], "-gdwarf"))
 	    as_fatal (_("unknown DWARF option %s\n"), old_argv[optind - 1]);
+	  else if (old_argv[optind - 1][1] == 'g' && optarg != NULL)
+	    as_fatal (_("unknown option `%s'"), old_argv[optind - 1]);
 
 	  if (md_debug_format_selector)
 	    debug_type = md_debug_format_selector (& use_gnu_debug_info_extensions);

gas/testsuite/gas/all/empty.s

diff --git a/gas/testsuite/gas/all/empty.s b/gas/testsuite/gas/all/empty.s
new file mode 100644
index 0000000..6ac6c76
--- /dev/null
+++ b/gas/testsuite/gas/all/empty.s
@@ -0,0 +1 @@
+/* Empty input.  */

gas/testsuite/gas/all/gas.exp

diff --git a/gas/testsuite/gas/all/gas.exp b/gas/testsuite/gas/all/gas.exp
index ae7957b..db92712 100644
--- a/gas/testsuite/gas/all/gas.exp
+++ b/gas/testsuite/gas/all/gas.exp
@@ -506,3 +506,4 @@
 run_dump_test "pr27381"
 run_dump_test "multibyte1"
 run_dump_test "multibyte2"
+run_dump_test "pr29067"

gas/testsuite/gas/all/pr29067.d

diff --git a/gas/testsuite/gas/all/pr29067.d b/gas/testsuite/gas/all/pr29067.d
new file mode 100644
index 0000000..17a8eef
--- /dev/null
+++ b/gas/testsuite/gas/all/pr29067.d
@@ -0,0 +1,2 @@
+#as: -gsomething-not-already-a-long-option
+#error_output: pr29067.err

gas/testsuite/gas/all/pr29067.err

diff --git a/gas/testsuite/gas/all/pr29067.err b/gas/testsuite/gas/all/pr29067.err
new file mode 100644
index 0000000..e5a1b27
--- /dev/null
+++ b/gas/testsuite/gas/all/pr29067.err
@@ -0,0 +1,2 @@
+Assembler messages:
+Fatal error: unknown option `-gsomething-not-already-a-long-option'