feature gate for datetime support - 2nd part

Cargo.toml

@@ -14,6 +14,7 @@ documentation = "https://georust.github.io/gdal/"
 bindgen = ["gdal-sys/bindgen"]
 gdal_2_2 = ["gdal-sys/min_gdal_version_2_2"]
 array = ["ndarray"]
+datetime = ["chrono"]
 
 [dependencies]
 failure = "0.1"
@@ -24,7 +25,7 @@ geo-types = "0.4"
 gdal-sys = "0.2"
 num-traits = "0.2"
 ndarray = {version = "0.12.1", optional = true }
-chrono = "0.4"
+chrono = { version = "0.4", optional = true }
 
 [workspace]
 members = ["gdal-sys"]

examples/read_write_ogr_datetime.rs

@@ -1,14 +1,20 @@
+
 extern crate gdal;
+#[cfg(feature = "datetime")]
 extern crate chrono;
 
 use std::path::Path;
 use gdal::errors::Error;
 use gdal::vector::*;
 use std::fs;
+#[cfg(feature = "datetime")]
 use chrono::Duration;
 use std::ops::Add;
 
+#[cfg(feature = "datetime")]
 fn run() -> Result<(), Error> {
+    println!("gdal crate was build with datetime support");
+
     let mut dataset_a = Dataset::open(Path::new("fixtures/points_with_datetime.json"))?;
     let layer_a = dataset_a.layer(0)?;
 
@@ -55,6 +61,13 @@ fn run() -> Result<(), Error> {
     Ok(())
 }
 
+#[cfg(not(feature = "datetime"))]
+fn run() -> Result<(), Error> {
+    println!("gdal crate was build without datetime support");
+    Ok(())
+}
+
+
 fn main() {
     run().unwrap();
 }

src/lib.rs

@@ -30,6 +30,8 @@ extern crate num_traits;
 
 #[cfg(feature = "ndarray")]
 extern crate ndarray;
+
+#[cfg(feature = "datetime")]
 extern crate chrono;
 
 pub use version::version_info;