gdb: remove --disable-gdbmi configure option

I noticed that the --disable-gdbmi option was broken for almost a year
(since 740b42ceb7c "gdb/python/mi: create MI commands using python").

The problem today is the python/py-cmd.c file.  It is included in the
build if Python support is enabled, and it calls into some MI functions
(e.g. insert_mi_cmd_entry).  If MI support is disabled, we get some
undefined symbols like:

    mold: error: undefined symbol: insert_mi_cmd_entry(std::unique_ptr<mi_command, std::default_delete<mi_command> >)
    >>> referenced by py-micmd.c
    >>>               python/py-micmd.o:(micmdpy_install_command(micmdpy_object*))

The python/py-cmd.c file should be included in the build if both Python
and MI support are enabled.  It is not a case we support today, but it
could be done with a bit more configure code.  However, I think we
should just remove the --disable-gdbmi option, and just include MI
support unconditionally.

Tom Tromey proposed a while ago to remove this option, but it ended
staying:

  https://inbox.sourceware.org/gdb-patches/20180628172132.28843-1-tom@tromey.com/

However, there was no strong opposition to remove it.  The argument was
just "bah, it doesn't hurt anybody".

But given today's case, I would rather remove complexity rather than add
some.  I couldn't find anybody caring deeply for that option, and it's
not like MI adds any external dependency.  It's just a bit more code.

Removing the option will not break anybody using --disable-gdbmi (it can
be found in many build scripts [1]), since we don't flag invalid
configure flags.

So, remove the option from configure.ac, and adjust Makefile.in
accordingly to always include the MI objects in the build.

[1] https://github.com/search?q=%22--disable-gdbmi%22&type=code

Change-Id: Ifcaa8c9fc4abc6fa686ed5fd984598644f745240
Approved-By: Tom Tromey <tom@tromey.com>

1 files changed, 3 insertions, 5 deletions

diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index ad9b9e5..4691cad 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -293,6 +293,7 @@ SUBDIR_MI_SRCS = \
 	mi/mi-cmd-target.c \
 	mi/mi-cmd-var.c \
 	mi/mi-cmds.c \
+	mi/mi-common.c \
 	mi/mi-console.c \
 	mi/mi-getopt.c \
 	mi/mi-interp.c \
@@ -303,10 +304,6 @@ SUBDIR_MI_SRCS = \
 
 SUBDIR_MI_OBS = $(patsubst %.c,%.o,$(SUBDIR_MI_SRCS))
 
-SUBDIR_MI_DEPS =
-SUBDIR_MI_LDFLAGS =
-SUBDIR_MI_CFLAGS =
-
 #
 # TUI sub directory definitions
 #
@@ -1251,8 +1248,8 @@ SFILES = \
 	stub-termcap.c \
 	symfile-mem.c \
 	ui-file.h \
-	mi/mi-common.c \
 	$(SUBDIR_CLI_SRCS) \
+	$(SUBDIR_MI_SRCS) \
 	$(SUBDIR_TARGET_SRCS) \
 	$(COMMON_SFILES) \
 	$(SUBDIR_GCC_COMPILE_SRCS)
@@ -1866,6 +1863,7 @@ COMMON_OBS = $(DEPFILES) $(CONFIG_OBS) $(YYOBJ) \
 	xml-builtin.o \
 	$(patsubst %.c,%.o,$(COMMON_SFILES)) \
 	$(SUBDIR_CLI_OBS) \
+	$(SUBDIR_MI_OBS) \
 	$(SUBDIR_TARGET_OBS) \
 	$(SUBDIR_GCC_COMPILE_OBS)