Clean up the usage of z_const and respect const usage within zlib.

This patch allows zlib to compile cleanly with the -Wcast-qual gcc
warning enabled, but only if ZLIB_CONST is defined, which adds
const to next_in and msg in z_stream and in the in_func prototype.
A --const option is added to ./configure which adds -DZLIB_CONST
to the compile flags, and adds -Wcast-qual to the compile flags
when ZLIBGCCWARN is set in the environment.

1 files changed, 4 insertions, 4 deletions

diff --git a/test/example.c b/test/example.c
index f515a48..138a699 100644
--- a/test/example.c
+++ b/test/example.c
@@ -26,7 +26,7 @@
     } \
 }
 
-const char hello[] = "hello, hello!";
+z_const char hello[] = "hello, hello!";
 /* "hello world" would be more standard, but the repeated "hello"
  * stresses the compression code better, sorry...
  */
@@ -212,7 +212,7 @@ void test_deflate(compr, comprLen)
     err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION);
     CHECK_ERR(err, "deflateInit");
 
-    c_stream.next_in  = (Bytef*)hello;
+    c_stream.next_in  = (z_const unsigned char *)hello;
     c_stream.next_out = compr;
 
     while (c_stream.total_in != len && c_stream.total_out < comprLen) {
@@ -387,7 +387,7 @@ void test_flush(compr, comprLen)
     err = deflateInit(&c_stream, Z_DEFAULT_COMPRESSION);
     CHECK_ERR(err, "deflateInit");
 
-    c_stream.next_in  = (Bytef*)hello;
+    c_stream.next_in  = (z_const unsigned char *)hello;
     c_stream.next_out = compr;
     c_stream.avail_in = 3;
     c_stream.avail_out = (uInt)*comprLen;
@@ -476,7 +476,7 @@ void test_dict_deflate(compr, comprLen)
     c_stream.next_out = compr;
     c_stream.avail_out = (uInt)comprLen;
 
-    c_stream.next_in = (Bytef*)hello;
+    c_stream.next_in = (z_const unsigned char *)hello;
     c_stream.avail_in = (uInt)strlen(hello)+1;
 
     err = deflate(&c_stream, Z_FINISH);