Request to add configure.ac file to future zlib builds

[HathewayWill]

zlib-1.3.1/watcom/watcom_f.mak
zlib-1.3.1/watcom/watcom_l.mak
**autoreconf: error: 'configure.ac' is required**
Checking for shared library support...
Building shared library libz.so.1.3.1 with gcc.
Checking for size_t... Yes.
Checking for off64_t... Yes.
Checking for fseeko... Yes.
Checking for strerror... Yes.
Checking for unistd.h... Yes.
Checking for stdarg.h... Yes.
Checking whether to use vs[n]printf() or s[n]printf()... using vs[n]printf().
Checking for vsnprintf() in stdio.h... Yes.
Checking for return value of vsnprintf()... Yes.
Checking for attribute(visibility) support... Yes.
**automake: error: 'configure.ac' is required**

I ran into some frustrating errors recently when trying to compile zlib with Autotools, and I thought I’d share what I learned about configure.ac files. If you’ve been seeing errors like:

csharp
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autoreconf: error: 'configure.ac' is required
automake: error: 'configure.ac' is required
then you’re in the right place! Turns out, configure.ac is pretty essential when you're using Autotools, especially for a library like zlib. Here’s the scoop:

What’s configure.ac Anyway?
In simple terms, configure.ac is the main file that Autotools (especially autoconf) uses to create the configure script. This script is like the brains of the operation. It tailors the build process for your specific system, checking for important libraries, functions, and other system-specific features.

Without configure.ac, Autotools just doesn’t know what to do! That’s why you’re seeing errors when autoreconf and automake look for this file and can’t find it.

Why Does zlib Need It?
Now, zlib can be built without Autotools by using custom makefiles, but when you’re working across different environments, that approach gets messy. Adding configure.ac offers some big benefits, especially if you’re trying to make zlib work smoothly across different systems:

Portability: configure.ac helps make sure zlib can be built on a variety of platforms. It instructs Autotools to check for system-specific features, so you don’t have to manually tweak files for each new setup. This is a huge win if you're working on different Unix-like systems or specific Linux distros.

Automatic Dependency Checks: Autotools can handle compatibility checks with configure.ac. For example, it’ll check for things like fseeko, strerror, and standard headers (unistd.h, stdarg.h). This way, it can adjust the build process if any of these are missing. So you’re less likely to hit a build error halfway through because of a missing library or function.

Easy Customization: With a configure.ac file, you can use options like ./configure --prefix=/custom/path or ./configure --disable-shared to customize the build without touching the code. This is especially helpful if you want to change installation paths or adjust settings on the fly.

Future-Friendly: As zlib (or any other project) gets updated, managing system compatibility with configure.ac and Autotools is much simpler. Developers can add checks for new features or compatibility adjustments without rewriting makefiles. It’s like future-proofing the build process!

How to Add configure.ac to zlib
If you want to add configure.ac to your zlib setup, you might need to write a basic one that includes the key checks for zlib’s dependencies and compatibility options. Here's a simple example of what it might look like:

bash
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AC_INIT([zlib], [1.3.1])
AM_INIT_AUTOMAKE
AC_PROG_CC
AC_CHECK_HEADERS([unistd.h stdarg.h])

Add checks for other functions or types as needed

AC_OUTPUT
This file would go a long way toward smoothing out the build process. Once you have it, you can run autoreconf -i to generate the configure script, and then the usual ./configure, make, and make install should work without issues.

Final Thoughts
So, if you’re dealing with errors or just want to make zlib a bit more portable and user-friendly, adding configure.ac is a smart move. It might seem like extra work at first, but it’s worth it for the flexibility, fewer headaches, and long-term maintenance benefits.

Anyone else gone through the process of adding Autotools support to zlib or another project? I’d love to hear about your experiences or any tips you have!

Cheers,