Expose env vars pkg-config depends on

src/lib.rs

@@ -82,7 +82,7 @@ pub fn target_supported() -> bool {
    // override) and then also don't use pkg-config on MSVC as it's really not
    // meant to work there but when building MSVC code in a MSYS shell we may be
    // able to run pkg-config anyway.
    (host == target || env::var_os("PKG_CONFIG_ALLOW_CROSS").is_some()) &&
    (host == target || get_var_os("PKG_CONFIG_ALLOW_CROSS").is_some()) &&
    !target.contains("msvc")
}

@@ -330,7 +330,7 @@ impl Config {
    /// `pkg-config` is run.
    pub fn probe(&self, name: &str) -> Result<Library, Error> {
        let abort_var_name = format!("{}_NO_PKG_CONFIG", envify(name));
        if env::var_os(&abort_var_name).is_some() {
        if get_var_os(&abort_var_name).is_some() {
            return Err(Error::EnvNoPkgConfig(abort_var_name))
        } else if !target_supported() {
            if env::var("TARGET").unwrap_or(String::new()).contains("msvc") {
@@ -341,6 +341,22 @@ impl Config {
            }
        }

        // pkg-config can be configured via env vars,
        // and should be probed again if the configuration changes.
        // Unfortunately, this list is not exhaustive,
        // because arbitrary `PKG_CONFIG_$PKG_$VAR` can exist.
        // NB: `get_var_os` automatically marks vars as used.
        rerun_if_changed("PKG_CONFIG_PATH");
        rerun_if_changed("PKG_CONFIG_SYSTEM_INCLUDE_PATH");
        rerun_if_changed("CPATH");
        rerun_if_changed("INCLUDE");
        rerun_if_changed("PKG_CONFIG_ALLOW_SYSTEM_CFLAGS");
        rerun_if_changed("PKG_CONFIG_SYSTEM_LIBRARY_PATH");
        rerun_if_changed("PKG_CONFIG_ALLOW_SYSTEM_LIBS");
        rerun_if_changed("PKG_CONFIG_SYSROOT_DIR");
        rerun_if_changed("PKG_CONFIG_LIBDIR");
        rerun_if_changed("PKG_CONFIG_DISABLE_UNINSTALLED");

        let mut library = Library::new();

        let output = try!(run(self.command(name, &["--libs", "--cflags"])));
@@ -363,7 +379,7 @@ impl Config {
    }

    fn command(&self, name: &str, args: &[&str]) -> Command {
        let exe = env::var("PKG_CONFIG").unwrap_or(String::from("pkg-config"));
        let exe = get_var_os("PKG_CONFIG").unwrap_or(OsString::from("pkg-config"));
        let mut cmd = Command::new(exe);
        if self.is_static(name) {
            cmd.arg("--static");
@@ -461,13 +477,13 @@ impl Library {

fn infer_static(name: &str) -> bool {
    let name = envify(name);
    if env::var_os(&format!("{}_STATIC", name)).is_some() {
    if get_var_os(&format!("{}_STATIC", name)).is_some() {
        true
    } else if env::var_os(&format!("{}_DYNAMIC", name)).is_some() {
    } else if get_var_os(&format!("{}_DYNAMIC", name)).is_some() {
        false
    } else if env::var_os("PKG_CONFIG_ALL_STATIC").is_some() {
    } else if get_var_os("PKG_CONFIG_ALL_STATIC").is_some() {
        true
    } else if env::var_os("PKG_CONFIG_ALL_DYNAMIC").is_some() {
    } else if get_var_os("PKG_CONFIG_ALL_DYNAMIC").is_some() {
        false
    } else {
        false
@@ -480,6 +496,17 @@ fn envify(name: &str) -> String {
    }).collect()
}

/// Mark build as dependent on the variable
fn rerun_if_changed(var_name: &str) {
    println!("cargo:rerun-if-env-changed={}", var_name);
}

/// Get variable and mark the build as dependent on it
fn get_var_os(var_name: &str) -> Option<OsString> {
    rerun_if_changed(var_name);
    env::var_os(var_name)
}

/// System libraries should only be linked dynamically
fn is_static_available(name: &str, dirs: &[PathBuf]) -> bool {
    let libname = format!("lib{}.a", name);