From caa5b8f6f9582b3e9c28b0cd2c2dd9fd0f2e183f Mon Sep 17 00:00:00 2001
From: Markus Reiter <me@reitermark.us>
Date: Sat, 7 Sep 2019 14:18:21 +0200
Subject: [PATCH] Fall back to using `cargo` on the host when no image is
 found.

---
 src/docker.rs |  6 +++---
 src/main.rs   | 10 +++++++++-
 2 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/docker.rs b/src/docker.rs
index 56a02a02e..2b1f9e687 100644
--- a/src/docker.rs
+++ b/src/docker.rs
@@ -171,7 +171,7 @@ pub fn run(target: &Target,
         .run_and_get_status(verbose)
 }
 
-fn image(toml: Option<&Toml>, target: &Target) -> Result<String> {
+pub fn image(toml: Option<&Toml>, target: &Target) -> Result<String> {
     if let Some(toml) = toml {
         if let Some(image) = toml.image(target)?.map(|s| s.to_owned()) {
             return Ok(image)
@@ -181,8 +181,8 @@ fn image(toml: Option<&Toml>, target: &Target) -> Result<String> {
     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);
+        bail!("`cross` does not provide a Docker image for target {}, \
+               specify a custom image in `Cross.toml`.", triple);
     }
 
     let version = env!("CARGO_PKG_VERSION");
diff --git a/src/main.rs b/src/main.rs
index f8303c2fb..7eeff67b9 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -277,7 +277,15 @@ fn run() -> Result<ExitStatus> {
 
             let needs_interpreter = args.subcommand.map(|sc| sc.needs_interpreter()).unwrap_or(false);
 
-            if target.needs_docker() &&
+            let image_exists = match docker::image(toml.as_ref(), &target) {
+                Ok(_) => true,
+                Err(err) => {
+                    eprintln!("Warning: {} Falling back to `cargo` on the host.", err);
+                    false
+                },
+            };
+
+            if image_exists && target.needs_docker() &&
                args.subcommand.map(|sc| sc.needs_docker()).unwrap_or(false) {
                 if version_meta.needs_interpreter() &&
                     needs_interpreter &&