bpo-13501: allow choosing between readline and libedit (GH-24189)

In contrast to macOS, libedit is available as its own include file and
library on Linux systems to prevent file name clashes. So if both
libraries are available on the system, readline is currently chosen by
default; and if only libedit is available, it is not found at all. This
patch adds a way to link against libedit by adding the following
arguments to configure:

  --with-readline           link against libreadline (the default)
  --with-readline=editline  link against libeditline
  --with-readline=no        disable building the readline module
  --without-readline        (same)

The runtime detection of libedit vs. readline was already done in commit
7105319ada2e66365902 (2019-12-04, serge-sans-paille: "bpo-38634: Allow
non-apple build to cope with libedit (GH-16986)").

Fixes: GH-12076 ("bpo-13501 Build or disable readline with Editline")
Fixes: bpo-13501 ("Make libedit support more generic; port readline / libedit to FreeBSD")
Co-authored-by: Enji Cooper (ngie-eign)
Co-authored-by: Martin Panter (vadmium)
Co-authored-by: Robert Marshall (kellinm)

1 files changed, 143 insertions, 123 deletions

diff --git a/configure b/configure
index 39fb15f..8e0cc71 100755
--- a/configure
+++ b/configure
@@ -849,6 +849,7 @@ with_libc
 enable_big_digits
 with_platlibdir
 with_wheel_pkg_dir
+with_readline
 with_computed_gotos
 with_ensurepip
 with_openssl
@@ -1581,6 +1582,8 @@ Optional Packages:
   --with-wheel-pkg-dir=PATH
                           Directory of wheel packages used by ensurepip
                           (default: none)
+  --with(out)-readline[=editline]
+                          use Editline for backend or disable readline module
   --with-computed-gotos   enable computed gotos in evaluation loop (enabled by
                           default on supported compilers)
   --with-ensurepip[=install|upgrade|no]
@@ -15602,24 +15605,49 @@ $as_echo "#define HAVE_GETC_UNLOCKED 1" >>confdefs.h
 
 fi
 
+
+# Check whether --with-readline was given.
+if test "${with_readline+set}" = set; then :
+  withval=$with_readline;
+else
+  with_readline=yes
+fi
+
+
 # check where readline lives
+py_cv_lib_readline=no
 # save the value of LIBS so we don't actually link Python with readline
 LIBS_no_readline=$LIBS
 
-# On some systems we need to link readline to a termcap compatible
-# library.  NOTE: Keep the precedence of listed libraries synchronised
-# with setup.py.
-py_cv_lib_readline=no
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking how to link readline libs" >&5
+if test "$with_readline" != no; then
+  case "$with_readline" in
+  editline|edit)
+    LIBREADLINE=edit
+
+$as_echo "#define WITH_EDITLINE 1" >>confdefs.h
+
+    ;;
+  yes|readline)
+    LIBREADLINE=readline
+    ;;
+  *)
+    as_fn_error $? "proper usage is --with(out)-readline[=editline]" "$LINENO" 5
+    ;;
+  esac
+
+  # On some systems we need to link readline to a termcap compatible
+  # library.  NOTE: Keep the precedence of listed libraries synchronised
+  # with setup.py.
+  { $as_echo "$as_me:${as_lineno-$LINENO}: checking how to link readline libs" >&5
 $as_echo_n "checking how to link readline libs... " >&6; }
-for py_libtermcap in "" tinfo ncursesw ncurses curses termcap; do
-  if test -z "$py_libtermcap"; then
-    READLINE_LIBS="-lreadline"
-  else
-    READLINE_LIBS="-lreadline -l$py_libtermcap"
-  fi
-  LIBS="$READLINE_LIBS $LIBS_no_readline"
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+  for py_libtermcap in "" tinfo ncursesw ncurses curses termcap; do
+    if test -z "$py_libtermcap"; then
+      READLINE_LIBS="-l$LIBREADLINE"
+    else
+      READLINE_LIBS="-l$LIBREADLINE -l$py_libtermcap"
+    fi
+    LIBS="$READLINE_LIBS $LIBS_no_readline"
+    cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
 /* Override any GCC internal prototype to avoid an error.
@@ -15642,73 +15670,67 @@ if ac_fn_c_try_link "$LINENO"; then :
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
-  if test $py_cv_lib_readline = yes; then
-    break
-  fi
-done
-# Uncomment this line if you want to use READINE_LIBS in Makefile or scripts
-#AC_SUBST([READLINE_LIBS])
-if test $py_cv_lib_readline = no; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: none" >&5
+    if test $py_cv_lib_readline = yes; then
+      break
+    fi
+  done
+
+  # Uncomment this line if you want to use READLINE_LIBS in Makefile or scripts
+  #AC_SUBST([READLINE_LIBS])
+  if test $py_cv_lib_readline = no; then
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: none" >&5
 $as_echo "none" >&6; }
-else
-  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READLINE_LIBS" >&5
+  else
+    { $as_echo "$as_me:${as_lineno-$LINENO}: result: $READLINE_LIBS" >&5
 $as_echo "$READLINE_LIBS" >&6; }
 
 $as_echo "#define HAVE_LIBREADLINE 1" >>confdefs.h
 
+  fi
 fi
 
-# check for readline 2.2
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <readline/readline.h>
-_ACEOF
-if ac_fn_c_try_cpp "$LINENO"; then :
-  have_readline=yes
-else
-  have_readline=no
-
-fi
-rm -f conftest.err conftest.i conftest.$ac_ext
-if test $have_readline = yes
-then
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <readline/readline.h>
+if test "$py_cv_lib_readline" = yes; then
+  # check for readline 2.2
+  ac_fn_c_check_decl "$LINENO" "rl_completion_append_character" "ac_cv_have_decl_rl_completion_append_character" "
+#include <stdio.h> /* Must be first for Gnu Readline */
+#ifdef WITH_EDITLINE
+# include <editline/readline.h>
+#else
+# include <readline/readline.h>
+#endif
 
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "extern int rl_completion_append_character;" >/dev/null 2>&1; then :
+"
+if test "x$ac_cv_have_decl_rl_completion_append_character" = xyes; then :
 
 $as_echo "#define HAVE_RL_COMPLETION_APPEND_CHARACTER 1" >>confdefs.h
 
 fi
-rm -f conftest*
 
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <readline/readline.h>
+  ac_fn_c_check_decl "$LINENO" "rl_completion_suppress_append" "ac_cv_have_decl_rl_completion_suppress_append" "
+#include <stdio.h> /* Must be first for Gnu Readline */
+#ifdef WITH_EDITLINE
+# include <editline/readline.h>
+#else
+# include <readline/readline.h>
+#endif
 
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "extern int rl_completion_suppress_append;" >/dev/null 2>&1; then :
+"
+if test "x$ac_cv_have_decl_rl_completion_suppress_append" = xyes; then :
 
 $as_echo "#define HAVE_RL_COMPLETION_SUPPRESS_APPEND 1" >>confdefs.h
 
 fi
-rm -f conftest*
 
-fi
 
-# check for readline 4.0
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_pre_input_hook in -lreadline" >&5
-$as_echo_n "checking for rl_pre_input_hook in -lreadline... " >&6; }
-if ${ac_cv_lib_readline_rl_pre_input_hook+:} false; then :
+  # check for readline 4.0
+  as_ac_Lib=`$as_echo "ac_cv_lib_$LIBREADLINE''_rl_pre_input_hook" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_pre_input_hook in -l$LIBREADLINE" >&5
+$as_echo_n "checking for rl_pre_input_hook in -l$LIBREADLINE... " >&6; }
+if eval \${$as_ac_Lib+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lreadline $READLINE_LIBS $LIBS"
+LIBS="-l$LIBREADLINE $READLINE_LIBS $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -15728,31 +15750,33 @@ return rl_pre_input_hook ();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_readline_rl_pre_input_hook=yes
+  eval "$as_ac_Lib=yes"
 else
-  ac_cv_lib_readline_rl_pre_input_hook=no
+  eval "$as_ac_Lib=no"
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_rl_pre_input_hook" >&5
-$as_echo "$ac_cv_lib_readline_rl_pre_input_hook" >&6; }
-if test "x$ac_cv_lib_readline_rl_pre_input_hook" = xyes; then :
+eval ac_res=\$$as_ac_Lib
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if eval test \"x\$"$as_ac_Lib"\" = x"yes"; then :
 
 $as_echo "#define HAVE_RL_PRE_INPUT_HOOK 1" >>confdefs.h
 
 fi
 
 
-# also in 4.0
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_completion_display_matches_hook in -lreadline" >&5
-$as_echo_n "checking for rl_completion_display_matches_hook in -lreadline... " >&6; }
-if ${ac_cv_lib_readline_rl_completion_display_matches_hook+:} false; then :
+  # also in 4.0
+  as_ac_Lib=`$as_echo "ac_cv_lib_$LIBREADLINE''_rl_completion_display_matches_hook" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_completion_display_matches_hook in -l$LIBREADLINE" >&5
+$as_echo_n "checking for rl_completion_display_matches_hook in -l$LIBREADLINE... " >&6; }
+if eval \${$as_ac_Lib+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lreadline $READLINE_LIBS $LIBS"
+LIBS="-l$LIBREADLINE $READLINE_LIBS $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -15772,31 +15796,33 @@ return rl_completion_display_matches_hook ();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_readline_rl_completion_display_matches_hook=yes
+  eval "$as_ac_Lib=yes"
 else
-  ac_cv_lib_readline_rl_completion_display_matches_hook=no
+  eval "$as_ac_Lib=no"
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_rl_completion_display_matches_hook" >&5
-$as_echo "$ac_cv_lib_readline_rl_completion_display_matches_hook" >&6; }
-if test "x$ac_cv_lib_readline_rl_completion_display_matches_hook" = xyes; then :
+eval ac_res=\$$as_ac_Lib
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if eval test \"x\$"$as_ac_Lib"\" = x"yes"; then :
 
 $as_echo "#define HAVE_RL_COMPLETION_DISPLAY_MATCHES_HOOK 1" >>confdefs.h
 
 fi
 
 
-# also in 4.0, but not in editline
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_resize_terminal in -lreadline" >&5
-$as_echo_n "checking for rl_resize_terminal in -lreadline... " >&6; }
-if ${ac_cv_lib_readline_rl_resize_terminal+:} false; then :
+  # also in 4.0, but not in editline
+  as_ac_Lib=`$as_echo "ac_cv_lib_$LIBREADLINE''_rl_resize_terminal" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_resize_terminal in -l$LIBREADLINE" >&5
+$as_echo_n "checking for rl_resize_terminal in -l$LIBREADLINE... " >&6; }
+if eval \${$as_ac_Lib+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lreadline $READLINE_LIBS $LIBS"
+LIBS="-l$LIBREADLINE $READLINE_LIBS $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -15816,31 +15842,33 @@ return rl_resize_terminal ();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_readline_rl_resize_terminal=yes
+  eval "$as_ac_Lib=yes"
 else
-  ac_cv_lib_readline_rl_resize_terminal=no
+  eval "$as_ac_Lib=no"
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_rl_resize_terminal" >&5
-$as_echo "$ac_cv_lib_readline_rl_resize_terminal" >&6; }
-if test "x$ac_cv_lib_readline_rl_resize_terminal" = xyes; then :
+eval ac_res=\$$as_ac_Lib
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if eval test \"x\$"$as_ac_Lib"\" = x"yes"; then :
 
 $as_echo "#define HAVE_RL_RESIZE_TERMINAL 1" >>confdefs.h
 
 fi
 
 
-# check for readline 4.2
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_completion_matches in -lreadline" >&5
-$as_echo_n "checking for rl_completion_matches in -lreadline... " >&6; }
-if ${ac_cv_lib_readline_rl_completion_matches+:} false; then :
+  # check for readline 4.2
+  as_ac_Lib=`$as_echo "ac_cv_lib_$LIBREADLINE''_rl_completion_matches" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for rl_completion_matches in -l$LIBREADLINE" >&5
+$as_echo_n "checking for rl_completion_matches in -l$LIBREADLINE... " >&6; }
+if eval \${$as_ac_Lib+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lreadline $READLINE_LIBS $LIBS"
+LIBS="-l$LIBREADLINE $READLINE_LIBS $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -15860,59 +15888,49 @@ return rl_completion_matches ();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_readline_rl_completion_matches=yes
+  eval "$as_ac_Lib=yes"
 else
-  ac_cv_lib_readline_rl_completion_matches=no
+  eval "$as_ac_Lib=no"
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_rl_completion_matches" >&5
-$as_echo "$ac_cv_lib_readline_rl_completion_matches" >&6; }
-if test "x$ac_cv_lib_readline_rl_completion_matches" = xyes; then :
+eval ac_res=\$$as_ac_Lib
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if eval test \"x\$"$as_ac_Lib"\" = x"yes"; then :
 
 $as_echo "#define HAVE_RL_COMPLETION_MATCHES 1" >>confdefs.h
 
 fi
 
 
-# also in readline 4.2
-cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <readline/readline.h>
-_ACEOF
-if ac_fn_c_try_cpp "$LINENO"; then :
-  have_readline=yes
-else
-  have_readline=no
-
-fi
-rm -f conftest.err conftest.i conftest.$ac_ext
-if test $have_readline = yes
-then
-  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
-/* end confdefs.h.  */
-#include <readline/readline.h>
+  # also in readline 4.2
+  ac_fn_c_check_decl "$LINENO" "rl_catch_signals" "ac_cv_have_decl_rl_catch_signals" "
+#include <stdio.h> /* Must be first for Gnu Readline */
+#ifdef WITH_EDITLINE
+# include <editline/readline.h>
+#else
+# include <readline/readline.h>
+#endif
 
-_ACEOF
-if (eval "$ac_cpp conftest.$ac_ext") 2>&5 |
-  $EGREP "extern int rl_catch_signals;" >/dev/null 2>&1; then :
+"
+if test "x$ac_cv_have_decl_rl_catch_signals" = xyes; then :
 
 $as_echo "#define HAVE_RL_CATCH_SIGNAL 1" >>confdefs.h
 
 fi
-rm -f conftest*
 
-fi
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for append_history in -lreadline" >&5
-$as_echo_n "checking for append_history in -lreadline... " >&6; }
-if ${ac_cv_lib_readline_append_history+:} false; then :
+  as_ac_Lib=`$as_echo "ac_cv_lib_$LIBREADLINE''_append_history" | $as_tr_sh`
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for append_history in -l$LIBREADLINE" >&5
+$as_echo_n "checking for append_history in -l$LIBREADLINE... " >&6; }
+if eval \${$as_ac_Lib+:} false; then :
   $as_echo_n "(cached) " >&6
 else
   ac_check_lib_save_LIBS=$LIBS
-LIBS="-lreadline $READLINE_LIBS $LIBS"
+LIBS="-l$LIBREADLINE $READLINE_LIBS $LIBS"
 cat confdefs.h - <<_ACEOF >conftest.$ac_ext
 /* end confdefs.h.  */
 
@@ -15932,22 +15950,24 @@ return append_history ();
 }
 _ACEOF
 if ac_fn_c_try_link "$LINENO"; then :
-  ac_cv_lib_readline_append_history=yes
+  eval "$as_ac_Lib=yes"
 else
-  ac_cv_lib_readline_append_history=no
+  eval "$as_ac_Lib=no"
 fi
 rm -f core conftest.err conftest.$ac_objext \
     conftest$ac_exeext conftest.$ac_ext
 LIBS=$ac_check_lib_save_LIBS
 fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_readline_append_history" >&5
-$as_echo "$ac_cv_lib_readline_append_history" >&6; }
-if test "x$ac_cv_lib_readline_append_history" = xyes; then :
+eval ac_res=\$$as_ac_Lib
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+if eval test \"x\$"$as_ac_Lib"\" = x"yes"; then :
 
 $as_echo "#define HAVE_RL_APPEND_HISTORY 1" >>confdefs.h
 
 fi
 
+fi
 
 # End of readline checks: restore LIBS
 LIBS=$LIBS_no_readline