[Bug] ZLib 1.3.1 does not build on Windows

[levicki]

Problem:

zlibvc.def(4): fatal error LNK1118: syntax error in 'VERSION' statement

From zlibvc.def:

LIBRARY
; zlib data compression and ZIP file I/O library

VERSION     1.3.1 <- this isn't valid version

If you read Microsoft documentation, this is the version which consist only of major and minor version and it gets written into PE file header (which means it could affect DLL loading by the OS) — it is not written into DLL resource table and it's not the same one users see when they check the details tab of the file in Windows Explorer.

This version should not be specified in module definition file unless you know what you are doing and have a very specific reason to do it. The fix is to remove the VERSION statement from zlibvc.def.

[madler]

https://github.com/madler/zlib/commit/b14484997a50c01b8d78f9db32516423573fc083

[levicki]

b144849

Thanks for a quick fix Mark, but I still don't see the value in setting VERSION to 1.3 — what you are doing is basically setting these fields:

They are completely invisible to end users and library users alike, and even if library users wanted to check them programmatically they'd have to deal with PE header structures only to get a truncated version.

If I am not mistaken, there's already zlibVersion() API as well as a way to extract a full file version from the PE resource table using Windows API. I must admit I am curious now as to why that was done.

[madler]

I left the VERSION's in there for now since they've always been there. (I have no idea why.) However I may be deleting the entire vstudio directory in favor of users using cmake to generate the build files.

[levicki]

@madler

I left the VERSION's in there for now since they've always been there. (I have no idea why.)

I guess it doesn't hurt to remain, but I hope that someone somewhere doesn't depend on it being there by now.

However I may be deleting the entire vstudio directory in favor of users using cmake to generate the build files.

Speaking of that, I tried using CMake to build it (by generating for VS 2022 x64) and it kinda works.

There's a difference in output file naming though:		vstudio	CMake
Debug DLL	zlibwapi.dll	zlibd.dll
Debug import LIB	zlibwapi.lib	zlibd.lib
Debug static LIB	zlibstat.lib	zlibstaticd.lib
Release DLL	zlibwapi.dll	zlib.dll
Release import LIB	zlibwapi.lib	zlib.lib
Release static LIB	zlibstat.lib	zlibstatic.lib

Also, there's a considerable size difference in produced files (both .lib and .dll) so you might want to investigate that.

When we are on the subject of naming, allow me to express my vote for having the same names for files produced by Debug and Release configurations.

Having same .lib and .dll names means I only have to set each of those options once when setting up a new project so I hope you stick with same output names like you did before.