From 2b2b55fcc25ddaba99b8fdaac151771ea1bcf658 Mon Sep 17 00:00:00 2001
From: Raph Levien <raph@google.com>
Date: Tue, 17 Jan 2017 13:22:05 -0800
Subject: [PATCH] Add dep-info generation

Make cargo output a ".d" file containing dependency info (in a format
that make and ninja can consume) for each artifact it produces. This
will help in integrating into other build systems.
---
 src/cargo/ops/cargo_rustc/mod.rs            |   5 +
 src/cargo/ops/cargo_rustc/output_depinfo.rs | 127 ++++++++++++++++++++
 2 files changed, 132 insertions(+)
 create mode 100644 src/cargo/ops/cargo_rustc/output_depinfo.rs

diff --git a/src/cargo/ops/cargo_rustc/mod.rs b/src/cargo/ops/cargo_rustc/mod.rs
index 370b7e1dc..3fb4033ed 100644
--- a/src/cargo/ops/cargo_rustc/mod.rs
+++ b/src/cargo/ops/cargo_rustc/mod.rs
@@ -18,6 +18,8 @@ use util::Freshness;
 use self::job::{Job, Work};
 use self::job_queue::JobQueue;
 
+use self::output_depinfo::output_depinfo;
+
 pub use self::compilation::Compilation;
 pub use self::context::{Context, Unit};
 pub use self::custom_build::{BuildOutput, BuildMap, BuildScripts};
@@ -30,6 +32,7 @@ mod job;
 mod job_queue;
 mod layout;
 mod links;
+mod output_depinfo;
 
 #[derive(PartialEq, Eq, Hash, Debug, Clone, Copy, PartialOrd, Ord)]
 pub enum Kind { Host, Target }
@@ -184,6 +187,8 @@ pub fn compile_targets<'a, 'cfg: 'a>(ws: &Workspace<'cfg>,
                 .or_insert(HashSet::new())
                 .extend(feats.iter().map(|feat| format!("feature=\"{}\"", feat)));
         }
+
+        output_depinfo(&mut cx, unit)?;
     }
 
     for (&(ref pkg, _), output) in cx.build_state.outputs.lock().unwrap().iter() {
diff --git a/src/cargo/ops/cargo_rustc/output_depinfo.rs b/src/cargo/ops/cargo_rustc/output_depinfo.rs
new file mode 100644
index 000000000..a571d516c
--- /dev/null
+++ b/src/cargo/ops/cargo_rustc/output_depinfo.rs
@@ -0,0 +1,127 @@
+use std::borrow::ToOwned;
+use std::collections::HashSet;
+use std::io::{Read, Write};
+use std::fs::File;
+use std::path::{Path, PathBuf};
+
+use core::{TargetKind};
+use ops::{Context, Unit};
+use util::{CargoResult, internal, human};
+
+#[derive(Debug)]
+struct DepLine {
+    target: String,
+    deps: Vec<String>,
+}
+
+struct DepFile {
+    dir: String,
+    deps: Vec<DepLine>,
+}
+
+fn render_filename<P: AsRef<Path>>(path: P, basedir: Option<&str>) -> CargoResult<String> {
+    let path = path.as_ref();
+    let relpath = match basedir {
+        None => path,
+        Some(base) => match path.strip_prefix(base) {
+            Ok(relpath) => relpath,
+            _ => path,
+        }
+    };
+    relpath.to_str().ok_or(internal("path not utf-8")).map(ToOwned::to_owned)
+}
+
+fn read_dep_file<P: AsRef<Path>>(path: P) -> CargoResult<DepFile> {
+    let mut file = File::open(&path).map_err(|_|
+        human("error opening ".to_string() + path.as_ref().to_str().unwrap_or("(bad unicode")))?;
+    let mut contents = String::new();
+    let _ = file.read_to_string(&mut contents)?;
+    let mut spl = contents.split('\0');
+    let dir = spl.next().ok_or(internal("dependency file empty"))?;
+    let dep_txt = spl.next().ok_or(internal("dependency file missing null byte"))?;
+    let mut result = Vec::new();
+    for line in dep_txt.lines() {
+        let mut line_spl = line.split(": ");
+        if let Some(target) = line_spl.next() {
+            if let Some(deps) = line_spl.next() {
+                let deps = deps.split_whitespace().map(ToOwned::to_owned).collect();
+                result.push(DepLine {
+                    target: target.to_string(),
+                    deps: deps,
+                });
+            }
+        }
+    }
+    Ok(DepFile {
+        dir: dir.to_string(),
+        deps: result,
+    })
+}
+
+fn add_deps(depfile: &DepFile, deps: &mut HashSet<PathBuf>) {
+    let dep_dir = PathBuf::from(&depfile.dir);
+    for depline in &depfile.deps {
+        for dep in &depline.deps {
+            deps.insert(dep_dir.join(dep));
+        }
+    }
+}
+
+// TODO: probably better to use Context::target_filenames for this
+fn target_filename(context: &mut Context, unit: &Unit) -> CargoResult<PathBuf> {
+    let (dir, base) = context.link_stem(&unit).ok_or(internal("can't get link stem"))?;
+    if unit.target.is_lib() {
+        Ok(dir.join(["lib", &base, ".rlib"].concat()))
+    } else {
+        Ok(dir.join(base))
+    }
+}
+
+fn add_deps_for_unit(deps: &mut HashSet<PathBuf>, context: &mut Context, unit: &Unit)
+    -> CargoResult<()>
+{
+    // TODO: this is duplicated against filename in fingerprint.rs
+    let kind = match *unit.target.kind() {
+        TargetKind::Lib(..) => "lib",
+        TargetKind::Bin => "bin",
+        TargetKind::Test => "integration-test",
+        TargetKind::Example => "example",
+        TargetKind::Bench => "bench",
+        TargetKind::CustomBuild => "build-script",
+    };
+    let flavor = if unit.profile.test {
+        "test-"
+    } else if unit.profile.doc {
+        "doc-"
+    } else {
+        ""
+    };
+    let dep_filename = ["dep-", flavor, kind, "-", &context.file_stem(&unit)].concat();
+    let path = context.fingerprint_dir(&unit).join(&dep_filename);
+    let depfile = read_dep_file(&path)?;
+    add_deps(&depfile, deps);
+    Ok(())
+}
+
+pub fn output_depinfo(context: &mut Context, unit: &Unit) -> CargoResult<()> {
+    let mut deps = HashSet::new();
+    add_deps_for_unit(&mut deps, context, unit)?;
+    for dep_unit in &context.dep_targets(unit)? {
+        let source_id = dep_unit.pkg.package_id().source_id();
+        if source_id.is_path() {
+            add_deps_for_unit(&mut deps, context, dep_unit)?;
+        }
+    }
+    let filename = target_filename(context, unit)?;
+    let mut output_path = filename.clone().into_os_string();
+    output_path.push(".d");
+    let basedir = None; // TODO
+    let target_fn = render_filename(filename, basedir)?;
+    let mut outfile = File::create(output_path)?;
+    write!(outfile, "{}:", target_fn)?;
+    for dep in &deps {
+        write!(outfile, " {}", render_filename(dep, basedir)?)?;
+    }
+    writeln!(outfile, "")?;
+    Ok(())
+}
-- 
2.30.2