Merge pull request #26 from japaric/no-atomics

support targets that don't support atomics

CHANGELOG.md

@@ -5,6 +5,12 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+### Added
+
+- Support targets that don't support atomics (`"max-atomic-width": 0`). For these targets, Xargo
+  only compiles the `core` and `rustc_unicode` crates as the other crates depend on atomics (e.g.
+  `alloc::Arc`).
+
 ## [v0.1.3] - 2016-04-24
 
 ### Added

Cargo.toml

@@ -14,6 +14,7 @@ chrono = "0.2.20"
 curl = "0.2.18"
 flate2 = "0.2.13"
 rustc_version = "0.1.7"
+serde_json = "0.8.0"
 tar = "0.4.4"
 tempdir = "0.3.4"
 term = "0.4.4"

src/main.rs

@@ -3,23 +3,28 @@ extern crate chrono;
 extern crate curl;
 extern crate flate2;
 extern crate rustc_version;
+extern crate serde_json;
 extern crate tar;
 extern crate tempdir;
 extern crate term;
 
-use std::{env, fs, mem};
+use std::collections::HashMap;
 use std::ffi::OsString;
 use std::fs::File;
 use std::hash::{Hash, SipHasher};
 use std::io::Read;
 use std::path::{Path, PathBuf};
 use std::process::Command;
+use std::{env, fs, mem};
 
 use cargo::util::{self, CargoResult, ChainError, Config, Filesystem};
 use cargo::core::shell::{ColorConfig, Verbosity};
+use serde_json::{de, Value};
 
 mod sysroot;
 
+type Spec = HashMap<String, Value>;
+
 fn main() {
     let config_opt = &mut None;
     if let Err(e) = run(config_opt) {
@@ -91,6 +96,7 @@ pub struct Target {
     hasher: SipHasher,
     // Path to $triple.json file
     path: PathBuf,
+    spec: Spec,
     triple: String,
 }
 
@@ -129,11 +135,18 @@ impl Target {
         Ok(Target {
             hasher: try!(hash(path)),
             path: try!(fs::canonicalize(path)),
+            spec: try!(parse_json(path)),
             triple: triple,
         })
     }
 }
 
+fn parse_json(p: &Path) -> CargoResult<Spec> {
+    let json = &mut String::new();
+    try!(try!(File::open(p)).read_to_string(json));
+    de::from_str(json).map_err(|_| util::human("Target specification file is not valid JSON"))
+}
+
 fn parse_args() -> CargoResult<(Command, Option<Target>, bool)> {
     let mut cargo = Command::new("cargo");
     let mut target = None;

src/sysroot.rs

@@ -179,6 +179,7 @@ fn rebuild_sysroot(config: &Config,
     }
 
     const CRATES: &'static [&'static str] = &["collections", "rand"];
+    const NO_ATOMICS_CRATES: &'static [&'static str] = &["rustc_unicode"];
     const TOML: &'static str = "[package]
 name = 'sysroot'
 version = '0.0.0'
@@ -233,8 +234,14 @@ version = '0.0.0'
     if verbose {
         cargo.arg("--verbose");
     }
-    for krate in CRATES {
-        cargo.args(&["-p", krate]);
+    if target.spec.get("max-atomic-width").map(|w| w.as_u64() == Some(0)) == Some(true) {
+        for krate in NO_ATOMICS_CRATES {
+            cargo.args(&["-p", krate]);
+        }
+    } else {
+        for krate in CRATES {
+            cargo.args(&["-p", krate]);
+        }
     }
     cargo.current_dir(td);
     let status = try!(cargo.status());

tests/smoke.rs

@@ -27,6 +27,18 @@ const CUSTOM_JSON: &'static str = r#"
     }
 "#;
 
+const NO_ATOMICS_JSON: &'static str = r#"
+    {
+      "arch": "arm",
+      "data-layout": "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64",
+      "llvm-target": "thumbv6m-none-eabi",
+      "max-atomic-width": 0,
+      "os": "none",
+      "target-endian": "little",
+      "target-pointer-width": "32"
+    }
+"#;
+
 fn xargo() -> Command {
     let mut path = try!(env::current_exe());
     path.pop();
@@ -250,3 +262,26 @@ fn rebuild_on_modified_rustflags() {
 
     cleanup(TARGET);
 }
+
+// For targets that don't support atomics, Xargo only compiles the `core` crate
+#[test]
+fn no_atomics() {
+    const TARGET: &'static str = "__no_atomics";
+    const CRATES: &'static [&'static str] = &["core", "rustc_unicode"];
+
+    let td = try!(TempDir::new("xargo"));
+    let td = &td.path();
+    try!(try!(File::create(td.join(format!("{}.json", TARGET))))
+        .write_all(NO_ATOMICS_JSON.as_bytes()));
+
+    run(xargo().args(&["init", "--vcs", "none", "--name", TARGET]).current_dir(td));
+    try!(try!(OpenOptions::new().truncate(true).write(true).open(td.join("src/lib.rs")))
+        .write_all(LIB_RS));
+    run(xargo().args(&["build", "--target", TARGET]).current_dir(td));
+
+    for krate in CRATES {
+        assert!(exists_rlib(krate, TARGET));
+    }
+
+    cleanup(TARGET);
+}