Make crate configurable and add memcpy config flag

Author: phil-opp

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+- Make behavior configurable through a `package.metadata.cargo-xbuild` table in the `Cargo.toml`
+  - Add a `memcpy` flags that specifies whether the `compiler_builtins` crate should be built with the `mem` feature enabled. Defaults to true.
 
 ## [v0.4.2] - 2018-05-07
 - Implement `--help`

Cargo.lock

@@ -15,11 +15,13 @@ error-chain = "0.7.2"
 fs2 = "0.4.1"
 libc = "0.2.18"
 rustc_version = "0.1.7"
-serde_json = "0.8.4"
+serde = "1.0"
+serde_derive = "1.0"
+serde_json = "1.0"
 tempdir = "0.3.5"
 toml = "0.2.1"
 walkdir = "1.0.3"
-cargo_metadata = "0.5.4"
+cargo_metadata = "0.5.5"
 
 [dev-dependencies]
 lazy_static = "0.2.8"

Cargo.toml

@@ -27,7 +27,18 @@ Instead of the "can't find crate for `core`" error you would get with a plain `c
 
 All additional arguments (e.g. `--release` or `--verbose`) are forwarded to `cargo build`.
 
-### Dev channel
+## Configuration
+
+To configure `cargo-xbuild` create a `package.metadata.cargo-xbuild` table in your `Cargo.toml`. The following options are available:
+
+```toml
+[package.metadata.cargo-xbuild]
+memcpy = true
+```
+
+- The `memcpy` flag defines whether the `mem` feature of the `compiler_builtins` crate should be activated. Turning this flag off allows to specify own versions of the `memcpy`, `memset` etc. functions.
+
+## Dev channel
 
 If you want to use a local Rust source instead of `rust-src` rustup component, you can set the `XARGO_RUST_SRC` environment variable.
 

README.md

@@ -0,0 +1,26 @@
+use serde_json;
+use cargo_metadata;
+
+#[derive(Debug, Deserialize, Hash)]
+pub struct Config {
+    pub memcpy: bool,
+}
+
+impl Default for Config {
+    fn default() -> Self {
+        Config {
+            memcpy: true,
+        }
+    }
+}
+
+impl Config {
+    pub fn from_metadata(metadata: &cargo_metadata::Metadata) -> Result<Config, serde_json::Error> {
+        let package_metadata = metadata.packages.first().map(|p| &p.metadata);
+        let crate_metadata = package_metadata.as_ref().and_then(|m| m.get("cargo-xbuild"));
+        match crate_metadata {
+            Some(json) => serde_json::from_value(json.clone()),
+            None => Ok(Config::default())
+        }
+    }
+}

src/config.rs

@@ -6,6 +6,8 @@ extern crate fs2;
 extern crate libc;
 extern crate rustc_version;
 extern crate serde_json;
+#[macro_use]
+extern crate serde_derive;
 extern crate tempdir;
 extern crate toml;
 extern crate walkdir;
@@ -30,6 +32,7 @@ mod rustc;
 mod sysroot;
 mod util;
 mod xargo;
+mod config;
 
 const HELP: &str = include_str!("help.txt");
 
@@ -145,6 +148,8 @@ fn build(args: cli::Args) -> Result<(ExitStatus)> {
         cargo_metadata::metadata(args.manifest_path()).expect("cargo metadata invocation failed");
     let root = Path::new(&metadata.workspace_root);
     let target_directory = Path::new(&metadata.target_directory);
+    let crate_config = config::Config::from_metadata(&metadata)
+        .map_err(|_| "parsing package.metadata.cargo-xbuild section failed")?;
 
     // We can't build sysroot with stable or beta due to unstable features
     let sysroot = rustc::sysroot(verbose)?;
@@ -195,6 +200,7 @@ fn build(args: cli::Args) -> Result<(ExitStatus)> {
             &cmode,
             &home,
             &root,
+            &crate_config,
             &rustflags,
             &meta,
             &src,

src/main.rs

@@ -16,6 +16,7 @@ use rustc::{Src, Sysroot, Target};
 use util;
 use xargo::Home;
 use cargo;
+use config::Config;
 
 #[cfg(feature = "dev")]
 fn profile() -> &'static str {
@@ -31,6 +32,7 @@ fn build(
     cmode: &CompilationMode,
     ctoml: &cargo::Toml,
     home: &Home,
+    config: &Config,
     src: &Src,
     hash: u64,
     verbose: bool,
@@ -43,7 +45,7 @@ fn build(
     util::mkdir(&dst)?;
 
     build_libcore(cmode, &ctoml, home, src, &dst, verbose)?;
-    build_libcompiler_builtins(cmode, &ctoml, home, src, &dst, verbose)?;
+    build_libcompiler_builtins(cmode, &ctoml, home, src, &dst, config, verbose)?;
     build_liballoc(cmode, &ctoml, home, src, &dst, verbose)?;
 
     // Create hash file
@@ -165,6 +167,7 @@ fn build_libcompiler_builtins(
     home: &Home,
     src: &Src,
     dst: &Path,
+    config: &Config,
     verbose: bool,
 ) -> Result<()> {
     const TOML: &'static str = r#"
@@ -182,13 +185,17 @@ version = "0.0.0"
         .to_string();
     let mut compiler_builtin_dep = Table::new();
     compiler_builtin_dep.insert("path".to_owned(), Value::String(path));
+
+    let mut features = vec![
+            Value::String("compiler-builtins".to_owned()),
+        ];
+    if config.memcpy {
+        features.push(Value::String("mem".to_owned()));
+    }
     compiler_builtin_dep.insert("default-features".to_owned(), Value::Boolean(false));
     compiler_builtin_dep.insert(
         "features".to_owned(),
-        Value::Array(vec![
-            Value::String("mem".to_owned()),
-            Value::String("compiler-builtins".to_owned()),
-        ]),
+        Value::Array(features),
     );
     let mut deps = Table::new();
     deps.insert(
@@ -255,6 +262,7 @@ fn hash(
     rustflags: &Rustflags,
     ctoml: &cargo::Toml,
     meta: &VersionMeta,
+    config: &Config,
 ) -> Result<u64> {
     let mut hasher = DefaultHasher::new();
 
@@ -270,13 +278,16 @@ fn hash(
         hash.hash(&mut hasher);
     }
 
+    config.hash(&mut hasher);
+
     Ok(hasher.finish())
 }
 
 pub fn update(
     cmode: &CompilationMode,
     home: &Home,
     root: &Path,
+    config: &Config,
     rustflags: &Rustflags,
     meta: &VersionMeta,
     src: &Src,
@@ -285,10 +296,10 @@ pub fn update(
 ) -> Result<()> {
     let ctoml = cargo::toml(root)?;
 
-    let hash = hash(cmode, rustflags, &ctoml, meta)?;
+    let hash = hash(cmode, rustflags, &ctoml, meta, config)?;
 
     if old_hash(cmode, home)? != Some(hash) {
-        build(cmode, &ctoml, home, src, hash, verbose)?;
+        build(cmode, &ctoml, home, config, src, hash, verbose)?;
     }
 
     // copy host artifacts into the sysroot, if necessary