From 5cccbe77b02cec69641856025a1744b1ca9558ed Mon Sep 17 00:00:00 2001
From: Brennan Kinney <5098581+polarathene@users.noreply.github.com>
Date: Fri, 14 Nov 2025 21:51:28 +1300
Subject: [PATCH 1/2] fix: Support opt-out via `LIBZ_SYS_STATIC=0`

This change refactors the `want_static` logic to additionally support `LIBZ_SYS_STATIC=0` as an explicit opt-out to the `static` feature when `libz-sys` is a transitive dependency and the build environment prefers to dynamic link `libz` instead.
---
 build.rs | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/build.rs b/build.rs
index cd11af8b..5228979f 100644
--- a/build.rs
+++ b/build.rs
@@ -30,12 +30,11 @@ fn main() {
         return;
     }
 
+    let want_static = should_link_static();
     // Don't run pkg-config if we're linking statically (we'll build below) and
     // also don't run pkg-config on FreeBSD/DragonFly. That'll end up printing
     // `-L /usr/lib` which wreaks havoc with linking to an OpenSSL in /usr/local/lib
     // (Ports, etc.)
-    let want_static =
-        cfg!(feature = "static") || env::var("LIBZ_SYS_STATIC").unwrap_or(String::new()) == "1";
     if !want_static &&
        !target.contains("msvc") && // pkg-config just never works here
        !(host_and_target_contain("freebsd") ||
@@ -238,3 +237,22 @@ fn zlib_installed(cfg: &mut cc::Build) -> bool {
 
     false
 }
+
+// The environment variable `LIBZ_SYS_STATIC` is first checked for a value of `0` (false) or `1` (true),
+// before considering the `static` feature when no explicit ENV value was detected.
+// When `libz-sys` is a transitive dependency from a crate that forces static linking via the `static` feature,
+// this enables the build environment to revert that preference via `LIBZ_SYS_STATIC=0`.
+// The default is otherwise `false`.
+fn should_link_static() -> bool {
+  let has_static_env: Option<&'static str> = option_env!("LIBZ_SYS_STATIC");
+  let has_static_cfg = cfg!(feature = "static");
+
+  has_static_env
+    .and_then(|s: &str| s.parse::<u8>().ok())
+    .and_then(|b| match b {
+      0 => Some(false),
+      1 => Some(true),
+      _ => None,
+    })
+    .unwrap_or(has_static_cfg)
+}

From 8cad56c64d210c80edc1a21fdeb2852f94192a19 Mon Sep 17 00:00:00 2001
From: Sebastian Thiel <sebastian.thiel@icloud.com>
Date: Sat, 15 Nov 2025 06:46:03 +0100
Subject: [PATCH 2/2] refactor

- turn comments into doc-comments for nicer display in editors.
---
 build.rs | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/build.rs b/build.rs
index 5228979f..2f922154 100644
--- a/build.rs
+++ b/build.rs
@@ -238,11 +238,11 @@ fn zlib_installed(cfg: &mut cc::Build) -> bool {
     false
 }
 
-// The environment variable `LIBZ_SYS_STATIC` is first checked for a value of `0` (false) or `1` (true),
-// before considering the `static` feature when no explicit ENV value was detected.
-// When `libz-sys` is a transitive dependency from a crate that forces static linking via the `static` feature,
-// this enables the build environment to revert that preference via `LIBZ_SYS_STATIC=0`.
-// The default is otherwise `false`.
+/// The environment variable `LIBZ_SYS_STATIC` is first checked for a value of `0` (false) or `1` (true),
+/// before considering the `static` feature when no explicit ENV value was detected.
+/// When `libz-sys` is a transitive dependency from a crate that forces static linking via the `static` feature,
+/// this enables the build environment to revert that preference via `LIBZ_SYS_STATIC=0`.
+/// The default is otherwise `false`.
 fn should_link_static() -> bool {
   let has_static_env: Option<&'static str> = option_env!("LIBZ_SYS_STATIC");
   let has_static_cfg = cfg!(feature = "static");