Make download optional

Author: termoshtt

intel-mkl-src/Cargo.toml

@@ -27,8 +27,8 @@ mkl-dynamic-lp64-seq   = []
 mkl-dynamic-ilp64-iomp = []
 mkl-dynamic-ilp64-seq  = []
 
-# Enable downloading from AWS S3 when not found
-download = []
+# Enable downloading from AWS S3 when system MKL not found
+download = ["intel-mkl-tool/archive"]
 # (Experimental) Cache download archive ad $XDG_DATA_HOME/intel-mkl-tool/
 xdg-data-home = []
 

intel-mkl-src/build.rs

@@ -20,6 +20,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 // SOFTWARE.
 
+#![cfg_attr(feature = "download", allow(unreachable_code))]
+
 use anyhow::*;
 use intel_mkl_tool::*;
 use std::{env, path::*};
@@ -51,7 +53,8 @@ fn main() -> Result<()> {
     }
 
     // download if not found
-    if cfg!(feature = "download") {
+    #[cfg(feature = "download")]
+    {
         let path = if cfg!(feature = "xdg-data-home") {
             xdg_home_path()
         } else {
@@ -64,6 +67,8 @@ fn main() -> Result<()> {
         cfg.download(path)?;
         let entry = Entry::from_config(cfg).unwrap(); // must found
         entry.print_cargo_metadata();
+        return Ok(());
     }
-    Ok(())
+
+    bail!("No MKL found, and download flag is off.");
 }