Re: [PATCH 10/36] Add extern "C" to declarations of C symbols

Pedro Alves
2015-02-11T11:51:32Z

On 02/09/2015 11:20 PM, Pedro Alves wrote:

> As for the linux-tdep.c change: elf-bfd.h wraps itself in extern "C"
> already, while elf/common.h does not. Since elf/common.h is already
> included by "elf-bfd.h", simply remove the explicit elf/common.h
> include.

Dunno what I was thinking here. :-) This wasn't necessary, not
even before revised BFD extern "C" patch that went in.

Here's the updated patch without that bit.

(I've been rebasing the series and force-pushing to my github branch,
as patches are updated or pushed to master:
git@github.com:palves/gdb.git palves/cxx-conversion-attempt)

--------
From 76168c4f096717c5921fed547f561fd7e336fa36 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Mon, 9 Feb 2015 14:59:08 +0000
Subject: [PATCH] Add extern "C" to declarations of C symbols

These symbols are defined in C code, so in C++ mode we need to use
extern "C" to declare them. As extern "C" can't be used inside a
function's scope, we move the declarations to the global scope at the
same time.

gdb/ChangeLog:
2015-02-11 Pedro Alves <palves@redhat.com>

* cli-out.c (_rl_erase_entire_line): Move declaration out of
cli_mld_erase_entire_line, and make it extern "C".
* common/common-defs.h (EXTERN_C): New.
* completer.c (_rl_completion_prefix_display_length)
(_rl_print_completions_horizontally, QSFUNC): Move declarations
out of gdb_display_match_list_1.
(_rl_qsort_string_compare): Move declaration out of
gdb_display_match_list_1, and make it extern "C".
* defs.h (re_comp): Use EXTERN_C.
* maint.c (_mcleanup): Move declaration out of mcleanup_wrapper,
and make it extern "C".
(monstartup): Move declaration out of maintenance_set_profile_cmd,
and make it extern "C".
(main): Move declaration out of maintenance_set_profile_cmd.
* nat/linux-ptrace.c (linux_ptrace_attach_fail_reason_string): Use
EXTERN_C.
---
gdb/cli-out.c | 4 ++--
gdb/common/common-defs.h | 6 ++++++
gdb/completer.c | 10 ++++++----
gdb/defs.h | 2 +-
gdb/maint.c | 10 +++++-----
gdb/nat/linux-ptrace.c | 2 +-
6 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/gdb/cli-out.c b/gdb/cli-out.c
index 48f2a04..2a83169 100644
--- a/gdb/cli-out.c
+++ b/gdb/cli-out.c
@@ -452,13 +452,13 @@ cli_mld_flush (const struct match_list_displayer *displayer)
fflush (rl_outstream);
}

+EXTERN_C void _rl_erase_entire_line (void);
+
/* CLI version of displayer.erase_entire_line. */

static void
cli_mld_erase_entire_line (const struct match_list_displayer *displayer)
{
- extern void _rl_erase_entire_line (void);
-
_rl_erase_entire_line ();
}

diff --git a/gdb/common/common-defs.h b/gdb/common/common-defs.h
index e80d332..3020bd8 100644
--- a/gdb/common/common-defs.h
+++ b/gdb/common/common-defs.h
@@ -50,4 +50,10 @@
#include "cleanups.h"
#include "common-exceptions.h"

+#ifdef __cplusplus
+# define EXTERN_C extern "C"
+#else
+# define EXTERN_C extern
+#endif
+
#endif /* COMMON_DEFS_H */
diff --git a/gdb/completer.c b/gdb/completer.c
index bfd2788..774fb31 100644
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -1555,6 +1555,12 @@ gdb_complete_get_screenwidth (const struct match_list_displayer *displayer)
return displayer->width;
}

+extern int _rl_completion_prefix_display_length;
+extern int _rl_print_completions_horizontally;
+
+EXTERN_C int _rl_qsort_string_compare (const void *, const void *);
+typedef int QSFUNC (const void *, const void *);
+
/* GDB version of readline/complete.c:rl_display_match_list.
See gdb_display_match_list for a description of MATCHES, LEN, MAX.
Returns non-zero if all matches are displayed. */
@@ -1567,10 +1573,6 @@ gdb_display_match_list_1 (char **matches, int len, int max,
int i, j, k, l, common_length, sind;
char *temp, *t;
int page_completions = displayer->height != INT_MAX && pagination_enabled;
- extern int _rl_completion_prefix_display_length;
- extern int _rl_qsort_string_compare (const void *, const void *);
- extern int _rl_print_completions_horizontally;
- typedef int QSFUNC (const void *, const void *);

/* Find the length of the prefix common to all items: length as displayed
characters (common_length) and as a byte index into the matches (sind) */
diff --git a/gdb/defs.h b/gdb/defs.h
index a1cd45f..72512f6 100644
--- a/gdb/defs.h
+++ b/gdb/defs.h
@@ -249,7 +249,7 @@ extern int annotation_level; /* in stack.c */
"const char *" in unistd.h, so we can't declare the argument
as "char *". */

-extern char *re_comp (const char *);
+EXTERN_C char *re_comp (const char *);

/* From symfile.c */

diff --git a/gdb/maint.c b/gdb/maint.c
index be18a32..1adea2f 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -683,15 +683,18 @@ extern char etext;

static int profiling_state;

+EXTERN_C void _mcleanup (void);
+
static void
mcleanup_wrapper (void)
{
- extern void _mcleanup (void);
-
if (profiling_state)
_mcleanup ();
}

+EXTERN_C void monstartup (unsigned long, unsigned long);
+extern int main ();
+
static void
maintenance_set_profile_cmd (char *args, int from_tty,
struct cmd_list_element *c)
@@ -705,9 +708,6 @@ maintenance_set_profile_cmd (char *args, int from_tty,
{
static int profiling_initialized;

- extern void monstartup (unsigned long, unsigned long);
- extern int main();
-
if (!profiling_initialized)
{
atexit (mcleanup_wrapper);
diff --git a/gdb/nat/linux-ptrace.c b/gdb/nat/linux-ptrace.c
index 0ce258f..e36864c 100644
--- a/gdb/nat/linux-ptrace.c
+++ b/gdb/nat/linux-ptrace.c
@@ -84,7 +84,7 @@ linux_ptrace_attach_fail_reason_string (ptid_t ptid, int err)
#if defined __i386__ || defined __x86_64__

/* Address of the 'ret' instruction in asm code block below. */
-extern void (linux_ptrace_test_ret_to_nx_instr) (void);
+EXTERN_C void linux_ptrace_test_ret_to_nx_instr (void);

#include <sys/reg.h>
#include <sys/mman.h>
--
1.9.3