Re: [PATCH] Make host_address_to_string/gdb_print_host_address cast parameter to 'void *'

[Pedro Alves <palves@redhat.com>]

On 10/27/2015 04:55 PM, Simon Marchi wrote:
> On 27 October 2015 at 12:01, Pedro Alves <palves@redhat.com> wrote:
>> Fixes a set of errors like:
>>
>>  ../../src/gdb/symfile-debug.c: In function ‘int debug_qf_map_symtabs_matching_filename(objfile*, const char*, const char*, int (*)(symtab*, void*), void*)’:
>>  ../../src/gdb/symfile-debug.c:137:39: error: invalid conversion from ‘int (*)(symtab*, void*)’ to ‘const void*’ [-fpermissive]
>>         host_address_to_string (callback),
>>                                         ^
>>
>> Note this has to work with data and function pointers.  In C++11 we
>> may perhaps do something a bit safer, but we're not there yet, and I
>> don't think it really matters.  For now just always do a simple
>> C-style cast in host_address_to_string itself.  No point in adding a
>> void * cast to each and every caller.
>>
>> gdb/ChangeLog:
>> 2015-10-27  Pedro Alves  <palves@redhat.com>
>>
>>         * common/print-utils.c (host_address_to_string): Undef.
>>         * common/print-utils.h (host_address_to_string): Add a wrapper
>>         macro around the host_address_to_string function.
>>         * utils.c ():
> 
> You can drop this last line.

Whoops.

> I'm not a fan of the #undef, it makes it harder to follow what's
> happening.  Why not just rename the existing function to
> host_address_to_string_1?
> 
> Same for gdb_print_host_address.

I guess I was trying to keep "b gdb_print_host_address" working
or something.  Aka, no real good reason.  Here's the updated patch.

From d9ede3df945232d574c9421270f95a650d2238c8 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Tue, 27 Oct 2015 14:57:06 +0000
Subject: [PATCH] Make host_address_to_string/gdb_print_host_address cast
 parameter to 'void *'
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Fixes a set of errors like:

 ../../src/gdb/symfile-debug.c: In function ‘int debug_qf_map_symtabs_matching_filename(objfile*, const char*, const char*, int (*)(symtab*, void*), void*)’:
 ../../src/gdb/symfile-debug.c:137:39: error: invalid conversion from ‘int (*)(symtab*, void*)’ to ‘const void*’ [-fpermissive]
	host_address_to_string (callback),
					^

Note this has to work with data and function pointers.  In C++11 we
may perhaps do something a bit safer, but we're not there yet, and I
don't think it really matters.  For now just always do a simple
C-style cast in host_address_to_string itself.  No point in adding a
void * cast to each and every caller.

gdb/ChangeLog:
2015-10-27  Pedro Alves  <palves@redhat.com>

	* common/print-utils.c (host_address_to_string): Rename to ...
	(host_address_to_string_1): ... this.
	* common/print-utils.h (host_address_to_string): Reimplement as
	wrapper around host_address_to_string_1.
	* utils.c (gdb_print_host_address): Rename to ...
	(gdb_print_host_address_1): ... this.
	* utils.h (gdb_print_host_address): Reimplement as wrapper macro
	around	host_address_to_string_1.
---
 gdb/common/print-utils.c | 2 +-
 gdb/common/print-utils.h | 6 +++++-
 gdb/utils.c              | 2 +-
 gdb/utils.h              | 6 +++++-
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/gdb/common/print-utils.c b/gdb/common/print-utils.c
index 1c1a5c1..7eba07d 100644
--- a/gdb/common/print-utils.c
+++ b/gdb/common/print-utils.c
@@ -316,7 +316,7 @@ core_addr_to_string_nz (const CORE_ADDR addr)
 /* See print-utils.h.  */
 
 const char *
-host_address_to_string (const void *addr)
+host_address_to_string_1 (const void *addr)
 {
   char *str = get_cell ();
 
diff --git a/gdb/common/print-utils.h b/gdb/common/print-utils.h
index 8d16966..49bc09a 100644
--- a/gdb/common/print-utils.h
+++ b/gdb/common/print-utils.h
@@ -65,6 +65,10 @@ extern const char *core_addr_to_string (const CORE_ADDR addr);
 
 extern const char *core_addr_to_string_nz (const CORE_ADDR addr);
 
-extern const char *host_address_to_string (const void *addr);
+extern const char *host_address_to_string_1 (const void *addr);
+
+/* Wrapper that avoids adding a pointless cast to all callers.  */
+#define host_address_to_string(ADDR) \
+  host_address_to_string_1 ((const void *) (ADDR))
 
 #endif /* COMMON_CELLS_H */
diff --git a/gdb/utils.c b/gdb/utils.c
index afeff12..255aee8 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -1104,7 +1104,7 @@ print_spaces (int n, struct ui_file *file)
 /* Print a host address.  */
 
 void
-gdb_print_host_address (const void *addr, struct ui_file *stream)
+gdb_print_host_address_1 (const void *addr, struct ui_file *stream)
 {
   fprintf_filtered (stream, "%s", host_address_to_string (addr));
 }
diff --git a/gdb/utils.h b/gdb/utils.h
index 995a1cf..e1f3827 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -246,7 +246,11 @@ extern void fputstrn_unfiltered (const char *str, int n, int quotr,
 extern int filtered_printing_initialized (void);
 
 /* Display the host ADDR on STREAM formatted as ``0x%x''.  */
-extern void gdb_print_host_address (const void *addr, struct ui_file *stream);
+extern void gdb_print_host_address_1 (const void *addr, struct ui_file *stream);
+
+/* Wrapper that avoids adding a pointless cast to all callers.  */
+#define gdb_print_host_address(ADDR, STREAM) \
+  gdb_print_host_address_1 ((const void *) ADDR, STREAM)
 
 /* Convert CORE_ADDR to string in platform-specific manner.
    This is usually formatted similar to 0x%lx.  */
-- 
1.9.3