Move readline to the readline/readline subdirectory

readline turns out to be a bit of a stumbling block for the project to
move gdbsupport (and then gdbserver) to the top-level.

The issue is that readline headers are intended to be included with
names like "readline/readline.h".  To support this, gdb effectively
adds a -I option pointing to the top-level source directory -- but,
importantly, this option is not used when the system readline is used.

For gdbsupport, a -I option like this would always be needed, but that
in turn would break the system readline case.  This was PR build/17077,
fixed in commit a8a5dbcab8df0b3a9e04745d4fe8d64740acb323.

Previously, we had discussed this on the gdb-patches list in terms of
removing readline from the tree

    https://sourceware.org/ml/gdb-patches/2019-09/msg00317.html

However, Eli expressed some concerns, and Joel did as well (off-list).

Given those concerns, and the fact that a patch-free local readline is
relatively new in gdb (it was locally patched for years), I changed my
mind and decided to handle this situation by moving the readline
sources down a level.

That is, upstream readline is now in readline/readline, and the
top-level readline directory just contains the minimal configury
needed to build that.

This fixes the problem because, when gdb unconditionally adds a
-I$(top_srcdir), this will not find readline headers.  A separate -I
will be needed instead, which is exactly what's needed for
--with-system-readline.

gdb/ChangeLog
2019-10-23  Tom Tromey  <tom@tromey.com>

	* Makefile.in (READLINE_DIR): Update.

gdb/doc/ChangeLog
2019-10-23  Tom Tromey  <tom@tromey.com>

	* Makefile.in (READLINE_DIR): Update.

readline/ChangeLog
2019-10-23  Tom Tromey  <tom@tromey.com>

	Move old contents to readline/ subdirectory.
	* aclocal.m4, configure, configure.ac, .gitignore, Makefile.am,
	Makefile.in, README: New files.

Change-Id: Ice156a2ee09ea68722b48f64d97146d7428ea9e4

1 files changed, 20 insertions, 0 deletions

diff --git a/readline/Makefile.am b/readline/Makefile.am
new file mode 100644
index 00000000000..50b10b244cd
--- /dev/null
+++ b/readline/Makefile.am
@@ -0,0 +1,20 @@
+# Copyright (C) 2019 Free Software Foundation, Inc.
+
+# This file is part of GDB.
+
+# 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/>.
+
+AUTOMAKE_OPTIONS = no-dist foreign
+SUBDIRS = readline
+ACLOCAL_AMFLAGS = -I . -I ../config