Merge pull request #8 from LittleBoxOfSunshine/chhenk/crosscomp

Support cross compilation / CompileKind::target inference

Cargo.toml

@@ -17,3 +17,4 @@ include = ["src/", "example_files", "LICENSE-*", "README.md", "COPYRIGHT"]
 [dependencies]
 anyhow = "1.0"
 fs_extra = "1.3"
+build-target = "0.4"

src/lib.rs

@@ -1,16 +1,37 @@
+use std::result::Result::Ok;
+use std::env;
 use fs_extra::copy_items;
 use fs_extra::dir::CopyOptions;
-use std::path::Path;
+use std::path::{Path, PathBuf};
 use anyhow::*;
 
 pub fn copy_to_output(path: &str, build_type: &str) -> Result<()> {
-    let mut options = CopyOptions::new();
-    let mut from_path = Vec::new();
-    let out_path = format!("target/{}", build_type);
+    let mut out_path = PathBuf::new();
+    out_path.push("target");
+
+    // This is a hack, ideally we would plug into https://docs.rs/cargo/latest/cargo/core/compiler/enum.CompileKind.html
+    // However, since the path follows predictable rules https://doc.rust-lang.org/cargo/guide/build-cache.html
+    // we can just check our parent path for the pattern target/{triple}/{profile}.
+    // If it is present, we know CompileKind::Target was used, otherwise CompileKind::Host was used.
+    // Best effort since the existing tests aren't intended to be run in a real build this won't exist.
+    // Unclear if that also means people in the wild are using the crate similarly, so avoiding any risk of break.
+    if let Ok(triple) = build_target::target_triple() {
+        if let Some(out_dir) = env::var_os("OUT_DIR") {
+            if let Some(out_dir) = out_dir.to_str() {
+                if out_dir.contains(&format!("target{}{}", std::path::MAIN_SEPARATOR, triple)) {
+                    out_path.push(triple);
+                }
+            }
+        }
+    }
+
+    out_path.push(build_type);
 
     // Overwrite existing files with same name
+    let mut options = CopyOptions::new();
     options.overwrite = true;
 
+    let mut from_path = Vec::new();
     from_path.push(path);
     copy_items(&from_path, &out_path, &options)?;