Re: [PATCH 06/11] [C++/mingw] ser-tcp.c casts

Pedro Alves
2015-11-02T21:06:02Z

On 11/02/2015 08:55 PM, Pedro Alves wrote:
> On 11/02/2015 08:40 PM, Simon Marchi wrote:

>> You could have done exactly the opposite of the old comment, that is cast to
>> (char *). It shouldn't generate any warning in either case. But I think that
>> your way is fine too.
>
> Oh, good point. I always forget that implicit cast to void* works.
>
> I'll update the patch.

Here it is. Build tested on GNU/Linux and mingw.

---
From 574dbd59c93e29f494bad7688cb04b1672d3980a Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Mon, 2 Nov 2015 20:56:15 +0000
Subject: [PATCH] [C++/mingw] ser-tcp.c casts

Fixes a few errors like these:

../../src/gdb/ser-tcp.c: In function 'int net_open(serial*, const char*)':
../../src/gdb/ser-tcp.c:286:73: error: invalid conversion from 'void*' to 'char*' [-fpermissive]
res = getsockopt (scb->fd, SOL_SOCKET, SO_ERROR, (void *) &err, &len);
^

gdb/ChangeLog:
2015-11-01 Pedro Alves <palves@redhat.com>

* ser-tcp.c (net_open) : Cast getsockopt argument to char *
instead of void *. Update comment.
(net_read_prim): Cast recv argument to char * instead of void *.
(net_write_prim): Cast send argument to char *. Add comment.
---
gdb/ser-tcp.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/gdb/ser-tcp.c b/gdb/ser-tcp.c
index ce40b61..36196f3 100644
--- a/gdb/ser-tcp.c
+++ b/gdb/ser-tcp.c
@@ -280,10 +280,10 @@ net_open (struct serial *scb, const char *name)

len = sizeof (err);
/* On Windows, the fourth parameter to getsockopt is a "char *";
- on UNIX systems it is generally "void *". The cast to "void *"
- is OK everywhere, since in C "void *" can be implicitly
- converted to any pointer type. */
- res = getsockopt (scb->fd, SOL_SOCKET, SO_ERROR, (void *) &err, &len);
+ on UNIX systems it is generally "void *". The cast to "char *"
+ is OK everywhere, since in C++ any data pointer type can be
+ implicitly converted to "void *". */
+ res = getsockopt (scb->fd, SOL_SOCKET, SO_ERROR, (char *) &err, &len);
if (res < 0 || err)
{
/* Maybe the target still isn't ready to accept the connection. */
@@ -342,13 +342,17 @@ net_read_prim (struct serial *scb, size_t count)
/* Need to cast to silence -Wpointer-sign on MinGW, as Winsock's
'recv' takes 'char *' as second argument, while 'scb->buf' is
'unsigned char *'. */
- return recv (scb->fd, (void *) scb->buf, count, 0);
+ return recv (scb->fd, (char *) scb->buf, count, 0);
}

int
net_write_prim (struct serial *scb, const void *buf, size_t count)
{
- return send (scb->fd, buf, count, 0);
+ /* On Windows, the second parameter to send is a "const char *"; on
+ UNIX systems it is generally "const void *". The cast to "const
+ char *" is OK everywhere, since in C++ any data pointer type can
+ be implicitly converted to "const void *". */
+ return send (scb->fd, (const char *) buf, count, 0);
}

int
--
1.9.3