Building FreeType with external zlib 1.2.8 makes msvc 14 stop with
the following error.
ftgzip.c
zlib-1.2.8\zlib.h(86): error C2061:
syntax error: identifier 'z_const'
zlib-1.2.8\zlib.h(94): error C2054:
expected '(' to follow 'z_const'
zlib-1.2.8\zlib.h(94): error C2085:
'msg': not in formal parameter list
...
zlib-1.2.8\zlib.h(877): fatal error C1003:
error count exceeds 100; stopping compilation
The error happens because FreeType keeps an own copy of zlib-1.1.4
under `src/gzip'. When building `src/gzip/ftgzip.c' with
FT_CONFIG_OPTION_SYSTEM_ZLIB defined, it uses
#include <zlib.h>
which correctly finds an external `zlib.h', but `zlib.h' itself has
a line
#include "zconf.h"
which makes Visual Studio 2015 find `src/gzip/zconf.h' while
compiling the files in `src/gzip'.
* src/gzip/zconf.h: Rename to...
* src/gzip/ftzconf.h: ... this.
* src/gzip/zlib.h, src/gzip/rules.mk (GZIP_DRV_SRCS): Updated.
Werner Lemberg