Add --build-plan for 'cargo build'

With 'cargo build --build-plan', cargo does not actually run any
commands, but instead prints out what it would have done in the form of
Python data structures. The 'dependencies' structure lists the
dependencies between steps, and the 'commands' structure lists the
information required to run the commands from an external build system.

Fixes rust-lang#3815

src/bin/bench.rs

@@ -19,6 +19,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_lib: bool,
     flag_bin: Vec<String>,
     flag_bins: bool,
@@ -67,6 +68,7 @@ Options:
     -q, --quiet                  No output printed to stdout
     --color WHEN                 Coloring: auto, always, never
     --message-format FMT         Error format: human, json [default: human]
+    --build-plan                 Generate a build plan
     --no-fail-fast               Run all benchmarks regardless of failure
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
@@ -127,6 +129,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                             &options.flag_example, options.flag_examples,
                                             &options.flag_bench, options.flag_benches,),
             message_format: options.flag_message_format,
+            build_plan: options.flag_build_plan,
             target_rustdoc_args: None,
             target_rustc_args: None,
         },

src/bin/build.rs

@@ -18,6 +18,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_release: bool,
     flag_lib: bool,
     flag_bin: Vec<String>,
@@ -65,6 +66,7 @@ Options:
     -q, --quiet                  No output printed to stdout
     --color WHEN                 Coloring: auto, always, never
     --message-format FMT         Error format: human, json [default: human]
+    --build-plan                 Generate a build plan
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
 
@@ -115,6 +117,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                         &options.flag_example, options.flag_examples,
                                         &options.flag_bench, options.flag_benches,),
         message_format: options.flag_message_format,
+        build_plan: options.flag_build_plan,
         target_rustdoc_args: None,
         target_rustc_args: None,
     };

src/bin/check.rs

@@ -36,6 +36,7 @@ Options:
     -q, --quiet                  No output printed to stdout
     --color WHEN                 Coloring: auto, always, never
     --message-format FMT         Error format: human, json [default: human]
+    --build-plan                 Generate a build plan
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
 
@@ -62,6 +63,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_release: bool,
     flag_lib: bool,
     flag_bin: Vec<String>,
@@ -112,6 +114,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                         &options.flag_example, options.flag_examples,
                                         &options.flag_bench, options.flag_benches,),
         message_format: options.flag_message_format,
+        build_plan: options.flag_build_plan,
         target_rustdoc_args: None,
         target_rustc_args: None,
     };

src/bin/doc.rs

@@ -20,6 +20,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_package: Vec<String>,
     flag_lib: bool,
     flag_bin: Vec<String>,
@@ -55,6 +56,7 @@ Options:
     -q, --quiet                  No output printed to stdout
     --color WHEN                 Coloring: auto, always, never
     --message-format FMT         Error format: human, json [default: human]
+    --build-plan                 Generate a build plan
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
 
@@ -106,6 +108,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                             &empty, false,
                                             &empty, false),
             message_format: options.flag_message_format,
+            build_plan: options.flag_build_plan,
             release: options.flag_release,
             mode: ops::CompileMode::Doc {
                 deps: !options.flag_no_deps,

src/bin/install.rs

@@ -121,6 +121,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                         &options.flag_example, options.flag_examples,
                                         &[], false),
         message_format: ops::MessageFormat::Human,
+        build_plan: false,
         target_rustc_args: None,
         target_rustdoc_args: None,
     };

src/bin/run.rs

@@ -20,6 +20,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_release: bool,
     flag_frozen: bool,
     flag_locked: bool,
@@ -48,6 +49,7 @@ Options:
     -q, --quiet                  No output printed to stdout
     --color WHEN                 Coloring: auto, always, never
     --message-format FMT         Error format: human, json [default: human]
+    --build-plan                 Generate a build plan
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
 
@@ -101,6 +103,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                     &[], false)
         },
         message_format: options.flag_message_format,
+        build_plan: options.flag_build_plan,
         target_rustdoc_args: None,
         target_rustc_args: None,
     };

src/bin/rustc.rs

@@ -19,6 +19,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_release: bool,
     flag_lib: bool,
     flag_bin: Vec<String>,
@@ -64,6 +65,7 @@ Options:
     -q, --quiet              No output printed to stdout
     --color WHEN             Coloring: auto, always, never
     --message-format FMT     Error format: human, json [default: human]
+    --build-plan             Generate a build plan
     --frozen                 Require Cargo.lock and cache are up to date
     --locked                 Require Cargo.lock is up to date
 
@@ -122,6 +124,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                         &options.flag_example, options.flag_examples,
                                         &options.flag_bench, options.flag_benches,),
         message_format: options.flag_message_format,
+        build_plan: options.flag_build_plan,
         target_rustdoc_args: None,
         target_rustc_args: options.arg_opts.as_ref().map(|a| &a[..]),
     };

src/bin/rustdoc.rs

@@ -18,6 +18,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_package: Option<String>,
     flag_lib: bool,
     flag_bin: Vec<String>,
@@ -62,6 +63,7 @@ Options:
     -q, --quiet              No output printed to stdout
     --color WHEN             Coloring: auto, always, never
     --message-format FMT     Error format: human, json [default: human]
+    --build-plan             Generate a build plan
     --frozen                 Require Cargo.lock and cache are up to date
     --locked                 Require Cargo.lock is up to date
 
@@ -107,6 +109,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
                                             &options.flag_example, options.flag_examples,
                                             &options.flag_bench, options.flag_benches,),
             message_format: options.flag_message_format,
+            build_plan: options.flag_build_plan,
             mode: ops::CompileMode::Doc { deps: false },
             target_rustdoc_args: Some(&options.arg_opts),
             target_rustc_args: None,

src/bin/test.rs

@@ -30,6 +30,7 @@ pub struct Options {
     flag_quiet: Option<bool>,
     flag_color: Option<String>,
     flag_message_format: MessageFormat,
+    flag_build_plan: bool,
     flag_release: bool,
     flag_no_fail_fast: bool,
     flag_frozen: bool,
@@ -71,6 +72,7 @@ Options:
     -q, --quiet                  No output printed to stdout
     --color WHEN                 Coloring: auto, always, never
     --message-format FMT         Error format: human, json [default: human]
+    --build-plan                 Generate a build plan
     --no-fail-fast               Run all tests regardless of failure
     --frozen                     Require Cargo.lock and cache are up to date
     --locked                     Require Cargo.lock is up to date
@@ -159,6 +161,7 @@ pub fn execute(options: Options, config: &Config) -> CliResult {
             mode: mode,
             filter: filter,
             message_format: options.flag_message_format,
+            build_plan: options.flag_build_plan,
             target_rustdoc_args: None,
             target_rustc_args: None,
         },

src/cargo/ops/cargo_compile.rs

@@ -59,6 +59,8 @@ pub struct CompileOptions<'a> {
     pub mode: CompileMode,
     /// `--error_format` flag for the compiler.
     pub message_format: MessageFormat,
+    /// Output a build plan to stdout instead of actually compiling.
+    pub build_plan: bool,
     /// Extra arguments to be passed to rustdoc (for main crate and dependencies)
     pub target_rustdoc_args: Option<&'a [String]>,
     /// The specified target will be compiled with all the available arguments,
@@ -81,6 +83,7 @@ impl<'a> CompileOptions<'a> {
             release: false,
             filter: CompileFilter::Everything { required_features_filterable: false },
             message_format: MessageFormat::Human,
+            build_plan: false,
             target_rustdoc_args: None,
             target_rustc_args: None,
         }
@@ -196,6 +199,7 @@ pub fn compile_ws<'a>(ws: &Workspace<'a>,
     let CompileOptions { config, jobs, target, spec, features,
                          all_features, no_default_features,
                          release, mode, message_format,
+                         build_plan,
                          ref filter,
                          ref target_rustdoc_args,
                          ref target_rustc_args } = *options;
@@ -297,6 +301,7 @@ pub fn compile_ws<'a>(ws: &Workspace<'a>,
         build_config.release = release;
         build_config.test = mode == CompileMode::Test || mode == CompileMode::Bench;
         build_config.json_messages = message_format == MessageFormat::Json;
+        build_config.build_plan = build_plan;
         if let CompileMode::Doc { deps } = mode {
             build_config.doc_all = deps;
         }

src/cargo/ops/cargo_package.rs

@@ -302,6 +302,7 @@ fn run_verify(ws: &Workspace, tar: &File, opts: &PackageOpts) -> CargoResult<()>
         filter: ops::CompileFilter::Everything { required_features_filterable: true },
         release: false,
         message_format: ops::MessageFormat::Human,
+        build_plan: false,
         mode: ops::CompileMode::Build,
         target_rustdoc_args: None,
         target_rustc_args: None,

src/cargo/ops/cargo_rustc/job_queue.rs

@@ -3,6 +3,8 @@ use std::collections::hash_map::HashMap;
 use std::fmt;
 use std::io;
 use std::mem;
+use std::sync::Arc;
+use std::path::PathBuf;
 use std::sync::mpsc::{channel, Sender, Receiver};
 
 use crossbeam::{self, Scope};
@@ -56,6 +58,7 @@ pub struct JobState<'a> {
 
 enum Message<'a> {
     Run(String),
+    BuildPlan(PackageId, ProcessBuilder, Arc<Vec<(PathBuf, Option<PathBuf>, bool)>>),
     Stdout(String),
     Stderr(String),
     Token(io::Result<Acquired>),
@@ -67,6 +70,10 @@ impl<'a> JobState<'a> {
         let _ = self.tx.send(Message::Run(cmd.to_string()));
     }
 
+    pub fn build_plan(&self, pkg: PackageId, cmd: ProcessBuilder, filenames: Arc<Vec<(PathBuf, Option<PathBuf>, bool)>>) {
+        let _ = self.tx.send(Message::BuildPlan(pkg, cmd, filenames));
+    }
+
     pub fn stdout(&self, out: &str) {
         let _ = self.tx.send(Message::Stdout(out.to_string()));
     }
@@ -149,6 +156,7 @@ impl<'a> JobQueue<'a> {
 
         let mut tokens = Vec::new();
         let mut queue = Vec::new();
+        let build_plan = cx.build_config.build_plan;
         trace!("queue: {:#?}", self.queue);
 
         // Iteratively execute the entire dependency graph. Each turn of the
@@ -189,7 +197,7 @@ impl<'a> JobQueue<'a> {
             // we're able to perform some parallel work.
             while error.is_none() && self.active < tokens.len() + 1 && !queue.is_empty() {
                 let (key, job, fresh) = queue.remove(0);
-                self.run(key, fresh, job, cx.config, scope)?;
+                self.run(key, fresh, job, cx.config, scope, build_plan)?;
             }
 
             // If after all that we're not actually running anything then we're
@@ -209,6 +217,16 @@ impl<'a> JobQueue<'a> {
                 Message::Run(cmd) => {
                     cx.config.shell().verbose(|c| c.status("Running", &cmd))?;
                 }
+                Message::BuildPlan(pkg, cmd, filenames) => {
+                    println!("    {:?}: {{", pkg.name());
+                    println!("        'outputs': [");
+                    for &(ref dst, _, _) in filenames.iter() {
+                        println!("            {:?},", dst);
+                    }
+                    println!("        ],");
+                    cmd.output_build_plan();
+                    println!("    }},");
+                }
                 Message::Stdout(out) => {
                     if cx.config.extra_verbose() {
                         println!("{}", out);
@@ -269,7 +287,9 @@ impl<'a> JobQueue<'a> {
                                   build_type,
                                   opt_type,
                                   time_elapsed);
-            cx.config.shell().status("Finished", message)?;
+            if !build_plan {
+                cx.config.shell().status("Finished", message)?;
+            }
             Ok(())
         } else if let Some(e) = error {
             Err(e)
@@ -286,7 +306,8 @@ impl<'a> JobQueue<'a> {
            fresh: Freshness,
            job: Job,
            config: &Config,
-           scope: &Scope<'a>) -> CargoResult<()> {
+           scope: &Scope<'a>,
+           build_plan: bool) -> CargoResult<()> {
         info!("start: {:?}", key);
 
         self.active += 1;
@@ -304,8 +325,10 @@ impl<'a> JobQueue<'a> {
             Freshness::Dirty => { scope.spawn(doit); }
         }
 
-        // Print out some nice progress information
-        self.note_working_on(config, &key, fresh)?;
+        if !build_plan {
+            // Print out some nice progress information
+            self.note_working_on(config, &key, fresh)?;
+        }
 
         Ok(())
     }
@@ -385,6 +408,19 @@ impl<'a> JobQueue<'a> {
         }
         Ok(())
     }
+
+    pub fn output_build_plan(&self) {
+        let dep_map = self.queue.get_dep_map();
+        println!("dependencies = {{");
+        for (key, deps) in dep_map.iter() {
+            println!("    {:?}: [", key.pkg.name());
+            for dep in deps.0.iter() {
+                println!("        {:?},", dep.pkg.name());
+            }
+            println!("    ],");
+        }
+        println!("}}");
+    }
 }
 
 impl<'a> Key<'a> {