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

[Pedro Alves <palves at redhat dot com>]

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