Fix setting breakpoints or stepping on line 65535

This removes code that was present from the very first git revisison
7b4ac7e1ed2c4616bce56d1760807798be87ac9e from 1988.  It was in the
gdb/dbxread.c at the time (and makes more sense for dbx line info format
since line numbers are 16-bit entities in that debug format and debugging
files with more than 65535 lines would not work anyway) but moved from
there to gdb/buildsym.c which is used for dwarf line info as well, and
excluding an arbitrary line number does certainly not make sense nowadays.

Add a test case for line 65535

gdb:
2019-12-29  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* buildsym.c (buildsym_compunit::record_line): Do no longer ignore
	line 65535.

gdb/testsuite:
2019-12-29  Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* gdb.base/line65535.exp: New file.
	* gdb.base/line65535.c: New file.

5 files changed, 57 insertions, 6 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 097f2f3..54565ef 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2019-12-29  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	* buildsym.c (buildsym_compunit::record_line): Do no longer ignore
+	line 65535.
+
 2019-12-27  Tom Tromey  <tom@tromey.com>
 
 	* tui/tui-source.c (tui_source_window::do_scroll_vertical): Remove
diff --git a/gdb/buildsym.c b/gdb/buildsym.c
index df74508..1102933 100644
--- a/gdb/buildsym.c
+++ b/gdb/buildsym.c
@@ -670,12 +670,6 @@ buildsym_compunit::record_line (struct subfile *subfile, int line,
 {
   struct linetable_entry *e;
 
-  /* Ignore the dummy line number in libg.o */
-  if (line == 0xffff)
-    {
-      return;
-    }
-
   /* Make sure line vector exists and is big enough.  */
   if (!subfile->line_vector)
     {
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 31208bd..d85b757 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2019-12-29  Bernd Edlinger  <bernd.edlinger@hotmail.de>
+
+	* gdb.base/line65535.exp: New file.
+	* gdb.base/line65535.c: New file.
+
 2019-12-27  Simon Marchi  <simon.marchi@polymtl.ca>
 
 	* lib/ada.exp (gnat_runtime_has_debug_info): New proc.
diff --git a/gdb/testsuite/gdb.base/line65535.c b/gdb/testsuite/gdb.base/line65535.c
new file mode 100644
index 0000000..d80a294
--- /dev/null
+++ b/gdb/testsuite/gdb.base/line65535.c
@@ -0,0 +1,19 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2019 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#line 65535 "line65535.c"
+int main() { return 0; }
diff --git a/gdb/testsuite/gdb.base/line65535.exp b/gdb/testsuite/gdb.base/line65535.exp
new file mode 100644
index 0000000..095f151
--- /dev/null
+++ b/gdb/testsuite/gdb.base/line65535.exp
@@ -0,0 +1,28 @@
+# Copyright 2019 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This test tries to place a breakpoint on line 65535.
+# For the purpose of this test we are satisfied if the break
+# command succeeds, we will not try to actually run to that line.
+
+standard_testfile
+
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile debug]} {
+    return -1
+}
+
+gdb_test "break $srcfile:65535" \
+         ".*Breakpoint 1 at .*: file $srcfile, line 65535\\..*" \
+	 "break at line 65535"