Re: [PATCH] Silence iconv warnings on Leopard

["Blake Ramsdell" <blaker@gmail.com>]

On Dec 6, 2007 4:30 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> Umm. Why not just make the test be whether the following compiles cleanly?
>
>         #include <iconv.h>
>
>         extern size_t iconv(iconv_t cd,
>           char **inbuf, size_t *inbytesleft,
>           char **outbuf, size_t *outbytesleft);
>
> because if the compiler has seen a "const char **inbuf", then it  should
> error out with a "conflicting types for 'iconv'" style message..

Yeah, this is what I did:

diff --git a/configure.ac b/configure.ac
index 5f8a15b..675d3e0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -182,6 +182,29 @@ AC_SUBST(NEEDS_LIBICONV)
 AC_SUBST(NO_ICONV)
 test -n "$NEEDS_LIBICONV" && LIBS="$LIBS -liconv"
 #
+# Define OLD_ICONV if the iconv function prototype uses const** (Darwin and
+# some FreeBSD installations).
+AC_DEFUN([OLDICONVTEST_SRC], [
+#include <iconv.h>
+
+int main(void)
+{
+    char* value = "test";
+
+    (void) iconv (NULL, &value, NULL, NULL, NULL);
+}
+])
+AC_MSG_CHECKING([for old iconv])
+old_CFLAGS="$CFLAGS"
+CFLAGS="$CFLAGS -Werror"
+AC_COMPILE_IFELSE(OLDICONVTEST_SRC,
+	[AC_MSG_RESULT([no])
+	OLD_ICONV=],
+	[AC_MSG_RESULT([yes])
+	OLD_ICONV=UnfortunatelyYes])
+CFLAGS="$old_CFLAGS"
+AC_SUBST(OLD_ICONV)
+#
 # Define NO_DEFLATE_BOUND if deflateBound is missing from zlib.
 AC_DEFUN([ZLIBTEST_SRC], [
 #include <zlib.h>

The problem is that AC_COMPILE_IFELSE doesn't barf on warnings, so I
had to put in the CFLAGS hack to do -Werror (this is what Jakub did
also, I think).

So if this isn't rude to use -Werror (which is probably gcc-specific
in one or more ways), then fine. If it is rude to use -Werror, then
yeah, there needs to be some check for the warning, which I confess in
my five minutes of learning autoconf I don't understand well enough to
say if it's possible.

Blake
-- 
Blake Ramsdell | http://www.blakeramsdell.com