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[binutils-gdb] Fallback to stub-termcap.c on all hosts
- From: Pedro Alves <palves at sourceware dot org>
- To: gdb-cvs at sourceware dot org
- Date: 6 Apr 2015 11:40:44 -0000
- Subject: [binutils-gdb] Fallback to stub-termcap.c on all hosts
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=7a85168daf6036fee808dac9944161415189f8a4
commit 7a85168daf6036fee808dac9944161415189f8a4
Author: Pedro Alves <palves@redhat.com>
Date: Mon Apr 6 12:35:18 2015 +0100
Fallback to stub-termcap.c on all hosts
Currently building gdb is impossible without an installed termcap or
curses library. But, GDB already has a very minimal termcap in the
tree to handle this situation for Windows -- gdb/stub-termcap.c. This
patch makes that the fallback for all hosts.
Testing this on GNU/Linux (by simply hacking away the termcap/curses
detection in gdb/configure.ac), we trip on:
../readline/libreadline.a(terminal.o): In function `_rl_init_terminal_io':
/home/pedro/gdb/mygit/src/readline/terminal.c:527: undefined reference to `PC'
/home/pedro/gdb/mygit/src/readline/terminal.c:528: undefined reference to `BC'
/home/pedro/gdb/mygit/src/readline/terminal.c:529: undefined reference to `UP'
/home/pedro/gdb/mygit/src/readline/terminal.c:538: undefined reference to `PC'
/home/pedro/gdb/mygit/src/readline/terminal.c:539: undefined reference to `BC'
/home/pedro/gdb/mygit/src/readline/terminal.c:540: undefined reference to `UP'
These are globals that are normally defined by termcap (or ncurses'
termcap emulation).
Now, we could just define replacements in stub-termcap.c, but
readline/terminal.c (at least the copy in our tree) has this:
#if !defined (__linux__) && !defined (NCURSES_VERSION)
# if defined (__EMX__) || defined (NEED_EXTERN_PC)
extern
# endif /* __EMX__ || NEED_EXTERN_PC */
char PC, *BC, *UP;
#endif /* !__linux__ && !NCURSES_VERSION */
which can result in readline defining the globals too. That will
usually work out in C, given that "-fcommon" is usually the default
for C compilers, but that won't work for C++, or C with -fno-common
(link fails with "multiple definition" errors)...
Mirroring those #ifdef conditions in the stub termcap screams
"brittle" to me -- I can see them changing in latter readline
versions.
Work around that by simply using __attribute__((weak)).
Windows/PE/COFF's do support weak, but not on gcc 3.4 based toolchains
(4.8.x does work). Given the file never needed the variables while it
was Windows-only, just continue not defining them there. All other
supported hosts should support this.
gdb/ChangeLog:
2015-04-06 Pedro Alves <palves@redhat.com>
Bernd Edlinger <bernd.edlinger@hotmail.de>
* configure.ac: Remove the mingw32-specific stub-termcap.o
fallback, and instead fallback to the stub termcap on all hosts.
* configure: Regenerate.
* stub-termcap.c [!__MINGW32__] (PC, BC, UP): Define as weak
symbols.
Diff:
---
gdb/ChangeLog | 9 +++++++++
gdb/configure | 7 +------
gdb/configure.ac | 7 +------
gdb/stub-termcap.c | 21 ++++++++++++++++++++-
4 files changed, 31 insertions(+), 13 deletions(-)
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index fed4e9e..919e93c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,12 @@
+2015-04-06 Pedro Alves <palves@redhat.com>
+ Bernd Edlinger <bernd.edlinger@hotmail.de>
+
+ * configure.ac: Remove the mingw32-specific stub-termcap.o
+ fallback, and instead fallback to the stub termcap on all hosts.
+ * configure: Regenerate.
+ * stub-termcap.c [!__MINGW32__] (PC, BC, UP): Define as weak
+ symbols.
+
2015-04-03 Pierre-Marie de Rodat <derodat@adacore.com>
* gdbtypes.c (is_dynamic_type_internal): Remove the unused
diff --git a/gdb/configure b/gdb/configure
index b8d4a7a..f835157 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -7455,11 +7455,6 @@ case $host_os in
go32* | *djgpp*)
ac_cv_search_tgetent="none required"
;;
- *mingw32*)
- if test x"$curses_found" != xyes; then
- ac_cv_search_tgetent="none required"
- CONFIG_OBS="$CONFIG_OBS stub-termcap.o"
- fi ;;
esac
# These are the libraries checked by Readline.
@@ -7521,7 +7516,7 @@ fi
if test "$ac_cv_search_tgetent" = no; then
- as_fn_error "no termcap library found" "$LINENO" 5
+ CONFIG_OBS="$CONFIG_OBS stub-termcap.o"
fi
diff --git a/gdb/configure.ac b/gdb/configure.ac
index ace033e..c703e35 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -617,18 +617,13 @@ case $host_os in
go32* | *djgpp*)
ac_cv_search_tgetent="none required"
;;
- *mingw32*)
- if test x"$curses_found" != xyes; then
- ac_cv_search_tgetent="none required"
- CONFIG_OBS="$CONFIG_OBS stub-termcap.o"
- fi ;;
esac
# These are the libraries checked by Readline.
AC_SEARCH_LIBS(tgetent, [termcap tinfo curses ncurses])
if test "$ac_cv_search_tgetent" = no; then
- AC_MSG_ERROR([no termcap library found])
+ CONFIG_OBS="$CONFIG_OBS stub-termcap.o"
fi
AC_ARG_WITH([system-readline],
diff --git a/gdb/stub-termcap.c b/gdb/stub-termcap.c
index 5897d89..722929f 100644
--- a/gdb/stub-termcap.c
+++ b/gdb/stub-termcap.c
@@ -40,9 +40,28 @@ extern char *tgoto (const char *cap, int col, int row);
}
#endif
+/* These globals below are global termcap variables that readline
+ references.
+
+ Actually, depending on preprocessor conditions that we don't want
+ to mirror here (as they may change depending on readline versions),
+ readline may define these globals as well, relying on the linker
+ merging them if needed (-fcommon). That doesn't work with
+ -fno-common or C++, so instead we define the symbols as weak.
+ Don't do this on Windows though, as MinGW gcc 3.4.2 doesn't support
+ weak (later versions, e.g., 4.8, do support it). Given this stub
+ file originally was Windows only, and we only needed this when we
+ made it work on other hosts, it should be OK. */
+#ifndef __MINGW32__
+char PC __attribute__((weak));
+char *BC __attribute__((weak));
+char *UP __attribute__((weak));
+#endif
+
/* Each of the files below is a minimal implementation of the standard
termcap function with the same name, suitable for use in a Windows
- console window. */
+ console window, or when a real termcap/curses library isn't
+ available. */
int
tgetent (char *buffer, char *termtype)