[Zlib-devel] Allow read-only data as input

[Jonathan Nieder]

Mike Frysinger wrote:
> Mark Adler wrote:

>> What if we added a ZLIB_CONST #define that, if defined, would add the
>> const's in zlib.h where appropriate?

Sounds excellent to me, for what it's worth.

> what if we negated the logic so that people would get const by default
> ?  so people could define ZLIB_NO_CONST to avoid transitional logic.

That would needlessly cause existing programs that "free(s.next_in);"
to break without warning.

Maybe it makes sense to advertise some method to use today to avoid
breaking programs tomorrow, like so:

| The new ZLIB_CONST macro can be used to add consts in zlib.h where
| appropriate.  Please try it out:
|
|	#define ZLIB_CONST const
|	#include <zlib.h>
|
| and if it causes your program to emit compile-time warnings or
| fail compile, define ZLIB_CONST to be empty before including zlib.h:
|
|	#define ZLIB_CONST
|	#include <zlib.h>
|
| This way, if the default for ZLIB_CONST changes to const in some
| future zlib version, your program will not be affected.

Though tracking down the required casts (as in "free((Bytef *) p);")
is probably easy enough that it's hard to imagine wanting to ever do
that.

Jonathan