Merge #217

217: Simplify Target to use only to cases: BuiltIn and Custom r=Dylan-DPC a=malbarbo

In the current form, cross needs to known every target its supports.
This makes things too restrict. For example, its not possible to use a
custom target image for a target that cross does not provides a docker
image (like aarch64-unknown-linux-musl, for example). Cross refuses to
execute saying it does not support the specified target. Besides that,
to add a new docker image the cross code needs to be changed.

This changes simplifies the Target enum to have only two variants:
BuiltIn and Custom. Cross needs to known if a target is a custom target
so it can call xargo, otherwise, all BuitIn targets can be uniformly
handled.

Co-authored-by: Marco A L Barbosa <[email protected]>

Author: bors[bot]

build.rs

@@ -1,6 +1,6 @@
 use std::env;
 use std::error::Error;
-use std::fs::File;
+use std::fs::{read_dir, File};
 use std::io::Write;
 use std::path::PathBuf;
 use std::process::Command;
@@ -22,6 +22,11 @@ fn main() {
         .unwrap()
         .write_all(commit_info().as_bytes())
         .unwrap();
+
+    File::create(out_dir.join("docker-images.rs"))
+        .unwrap()
+        .write_all(docker_images().as_bytes())
+        .unwrap();
 }
 
 fn commit_info() -> String {
@@ -53,3 +58,19 @@ fn commit_date() -> Result<String, Some> {
         Err(Some {})
     }
 }
+
+fn docker_images() -> String {
+    let mut images = String::from("[");
+    let mut dir = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    dir.push("docker");
+    for entry in read_dir(dir).unwrap() {
+        let path = entry.unwrap().path();
+        if path.is_dir() {
+            images.push_str("\"");
+            images.push_str(path.file_name().unwrap().to_str().unwrap());
+            images.push_str("\", ");
+        }
+    }
+    images.push_str("]");
+    images
+}

src/docker.rs

@@ -12,6 +12,8 @@ use extensions::CommandExt;
 use id;
 use rustc;
 
+const DOCKER_IMAGES: &[&str] = &include!(concat!(env!("OUT_DIR"), "/docker-images.rs"));
+
 lazy_static! {
     /// Retrieve the Docker Daemon version.
     ///
@@ -145,18 +147,22 @@ pub fn run(target: &Target,
 }
 
 fn image(toml: Option<&Toml>, target: &Target) -> Result<String> {
-    Ok(if let Some(toml) = toml {
-            toml.image(target)?.map(|s| s.to_owned())
-        } else {
-            None
+    if let Some(toml) = toml {
+        if let Some(image) = toml.image(target)?.map(|s| s.to_owned()) {
+            return Ok(image)
         }
-        .unwrap_or_else(|| {
-            let version = env!("CARGO_PKG_VERSION");
-            let tag = if version.ends_with("-dev") {
-                Cow::from("latest")
-            } else {
-                Cow::from(format!("v{}", version))
-            };
-            format!("japaric/{}:{}", target.triple(), tag)
-        }))
+    }
+
+    let version = env!("CARGO_PKG_VERSION");
+    let tag = if version.ends_with("-dev") {
+        Cow::from("latest")
+    } else {
+        Cow::from(format!("v{}", version))
+    };
+    let triple = target.triple();
+    if !DOCKER_IMAGES.contains(&triple) {
+        bail!("cross does not provide docker image for {} target, \
+               specify a custom image in Cross.toml", triple);
+    }
+    Ok(format!("japaric/{}:{}", target.triple(), tag))
 }