Set PKG_CONFIG_SYSROOT_DIR based on SDKROOT for macOS

src/build.rs

@@ -1,3 +1,4 @@
+use std::env;
 use std::ops::{Deref, DerefMut};
 use std::path::{Path, PathBuf};
 use std::process::{self, Command};
@@ -203,6 +204,17 @@ impl Build {
                         build.env("WINAPI_NO_BUNDLED_LIBRARIES", "1");
                     }
 
+                    if raw_target.contains("apple-darwin") {
+                        if let Some(sdkroot) = env::var_os("SDKROOT") {
+                            if !sdkroot.is_empty()
+                                && env::var_os("PKG_CONFIG_SYSROOT_DIR").is_none()
+                            {
+                                // Set PKG_CONFIG_SYSROOT_DIR for pkg-config crate
+                                build.env("PKG_CONFIG_SYSROOT_DIR", sdkroot);
+                            }
+                        }
+                    }
+
                     // Enable unstable `target-applies-to-host` option automatically for nightly Rust
                     // when target is the same as host but may have specified glibc version
                     if host_target == raw_target

tests/hello-rustls/Cargo.toml

@@ -8,3 +8,6 @@ edition = "2018"
 [dependencies]
 reqwest = { version = "0.11.9", default-features = false, features = ["rustls-tls"] }
 tokio = { version = "1.0", features = ["macros", "rt-multi-thread"] }
+
+[target.'cfg(target_os = "macos")'.dependencies]
+libz-sys = "1.1.5"

tests/hello-rustls/src/main.rs

@@ -1,3 +1,6 @@
+#[cfg(target_os = "macos")]
+use libz_sys as _;
+
 #[tokio::main]
 async fn main() {
     let response = reqwest::Client::new()