Remove step.rs

1 files changed, 0 insertions, 1820 deletions

diff --git a/src/bootstrap/step.rs b/src/bootstrap/step.rs
deleted file mode 100644
index a1b26f44b7d..00000000000
--- a/src/bootstrap/step.rs
+++ /dev/null
@@ -1,1820 +0,0 @@
-// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! Definition of steps of the build system.
-//!
-//! This is where some of the real meat of rustbuild is located, in how we
-//! define targets and the dependencies amongst them. This file can sort of be
-//! viewed as just defining targets in a makefile which shell out to predefined
-//! functions elsewhere about how to execute the target.
-//!
-//! The primary function here you're likely interested in is the `build_rules`
-//! function. This will create a `Rules` structure which basically just lists
-//! everything that rustbuild can do. Each rule has a human-readable name, a
-//! path associated with it, some dependencies, and then a closure of how to
-//! actually perform the rule.
-//!
-//! All steps below are defined in self-contained units, so adding a new target
-//! to the build system should just involve adding the meta information here
-//! along with the actual implementation elsewhere. You can find more comments
-//! about how to define rules themselves below.
-
-use std::collections::{BTreeMap, HashSet, HashMap};
-use std::mem;
-use std::path::PathBuf;
-use std::process;
-
-use check::{self, TestKind};
-use compile;
-use dist;
-use doc;
-use flags::Subcommand;
-use install;
-use native;
-use {Compiler, Build, Mode};
-
-pub fn run(build: &Build) {
-    let rules = build_rules(build);
-    let steps = rules.plan();
-    rules.run(&steps);
-}
-
-pub fn build_rules<'a>(build: &'a Build) -> Rules {
-    let mut rules = Rules::new(build);
-
-    // This is the first rule that we're going to define for rustbuild, which is
-    // used to compile LLVM itself. All rules are added through the `rules`
-    // structure created above and are configured through a builder-style
-    // interface.
-    //
-    // First up we see the `build` method. This represents a rule that's part of
-    // the top-level `build` subcommand. For example `./x.py build` is what this
-    // is associating with. Note that this is normally only relevant if you flag
-    // a rule as `default`, which we'll talk about later.
-    //
-    // Next up we'll see two arguments to this method:
-    //
-    // * `llvm` - this is the "human readable" name of this target. This name is
-    //            not accessed anywhere outside this file itself (e.g. not in
-    //            the CLI nor elsewhere in rustbuild). The purpose of this is to
-    //            easily define dependencies between rules. That is, other rules
-    //            will depend on this with the name "llvm".
-    // * `src/llvm` - this is the relevant path to the rule that we're working
-    //                with. This path is the engine behind how commands like
-    //                `./x.py build src/llvm` work. This should typically point
-    //                to the relevant component, but if there's not really a
-    //                path to be assigned here you can pass something like
-    //                `path/to/nowhere` to ignore it.
-    //
-    // After we create the rule with the `build` method we can then configure
-    // various aspects of it. For example this LLVM rule uses `.host(true)` to
-    // flag that it's a rule only for host targets. In other words, LLVM isn't
-    // compiled for targets configured through `--target` (e.g. those we're just
-    // building a standard library for).
-    //
-    // Next up the `dep` method will add a dependency to this rule. The closure
-    // is yielded the step that represents executing the `llvm` rule itself
-    // (containing information like stage, host, target, ...) and then it must
-    // return a target that the step depends on. Here LLVM is actually
-    // interesting where a cross-compiled LLVM depends on the host LLVM, but
-    // otherwise it has no dependencies.
-    //
-    // To handle this we do a bit of dynamic dispatch to see what the dependency
-    // is. If we're building a LLVM for the build triple, then we don't actually
-    // have any dependencies! To do that we return a dependency on the `Step::noop()`
-    // target which does nothing.
-    //
-    // If we're build a cross-compiled LLVM, however, we need to assemble the
-    // libraries from the previous compiler. This step has the same name as
-    // ours (llvm) but we want it for a different target, so we use the
-    // builder-style methods on `Step` to configure this target to the build
-    // triple.
-    //
-    // Finally, to finish off this rule, we define how to actually execute it.
-    // That logic is all defined in the `native` module so we just delegate to
-    // the relevant function there. The argument to the closure passed to `run`
-    // is a `Step` (defined below) which encapsulates information like the
-    // stage, target, host, etc.
-    rules.build("llvm", "src/llvm")
-         .host(true)
-         .dep(move |s| {
-             if s.target == build.build {
-                 Step::noop()
-             } else {
-                 s.target(&build.build)
-             }
-         })
-         .run(move |s| native::llvm(build, s.target));
-
-    // Ok! After that example rule  that's hopefully enough to explain what's
-    // going on here. You can check out the API docs below and also see a bunch
-    // more examples of rules directly below as well.
-
-    // the compiler with no target libraries ready to go
-    rules.build("rustc", "src/rustc")
-         .dep(|s| s.name("create-sysroot").target(s.host))
-         .dep(move |s| {
-             if s.stage == 0 {
-                 Step::noop()
-             } else {
-                 s.name("librustc")
-                  .host(&build.build)
-                  .stage(s.stage - 1)
-             }
-         })
-         .run(move |s| compile::assemble_rustc(build, s.stage, s.target));
-
-    // Helper for loading an entire DAG of crates, rooted at `name`
-    let krates = |name: &str| {
-        let mut ret = Vec::new();
-        let mut list = vec![name];
-        let mut visited = HashSet::new();
-        while let Some(krate) = list.pop() {
-            let default = krate == name;
-            let krate = &build.crates[krate];
-            let path = krate.path.strip_prefix(&build.src)
-                // This handles out of tree paths
-                .unwrap_or(&krate.path);
-            ret.push((krate, path.to_str().unwrap(), default));
-            for dep in krate.deps.iter() {
-                if visited.insert(dep) && dep != "build_helper" {
-                    list.push(dep);
-                }
-            }
-        }
-        ret
-    };
-
-    // ========================================================================
-    // Crate compilations
-    //
-    // Tools used during the build system but not shipped
-    rules.build("create-sysroot", "path/to/nowhere")
-         .run(move |s| compile::create_sysroot(build, &s.compiler()));
-
-    // These rules are "pseudo rules" that don't actually do any work
-    // themselves, but represent a complete sysroot with the relevant compiler
-    // linked into place.
-    //
-    // That is, depending on "libstd" means that when the rule is completed then
-    // the `stage` sysroot for the compiler `host` will be available with a
-    // standard library built for `target` linked in place. Not all rules need
-    // the compiler itself to be available, just the standard library, so
-    // there's a distinction between the two.
-    rules.build("libstd", "src/libstd")
-         .dep(|s| s.name("rustc").target(s.host))
-         .dep(|s| s.name("libstd-link"));
-    rules.build("libtest", "src/libtest")
-         .dep(|s| s.name("libstd"))
-         .dep(|s| s.name("libtest-link"))
-         .default(true);
-    rules.build("librustc", "src/librustc")
-         .dep(|s| s.name("libtest"))
-         .dep(|s| s.name("librustc-link"))
-         .host(true)
-         .default(true);
-
-    // Helper method to define the rules to link a crate into its place in the
-    // sysroot.
-    //
-    // The logic here is a little subtle as there's a few cases to consider.
-    // Not all combinations of (stage, host, target) actually require something
-    // to be compiled, but rather libraries could get propagated from a
-    // different location. For example:
-    //
-    // * Any crate with a `host` that's not the build triple will not actually
-    //   compile something. A different `host` means that the build triple will
-    //   actually compile the libraries, and then we'll copy them over from the
-    //   build triple to the `host` directory.
-    //
-    // * Some crates aren't even compiled by the build triple, but may be copied
-    //   from previous stages. For example if we're not doing a full bootstrap
-    //   then we may just depend on the stage1 versions of libraries to be
-    //   available to get linked forward.
-    //
-    // * Finally, there are some cases, however, which do indeed comiple crates
-    //   and link them into place afterwards.
-    //
-    // The rule definition below mirrors these three cases. The `dep` method
-    // calculates the correct dependency which either comes from stage1, a
-    // different compiler, or from actually building the crate itself (the `dep`
-    // rule). The `run` rule then mirrors these three cases and links the cases
-    // forward into the compiler sysroot specified from the correct location.
-    fn crate_rule<'a, 'b>(build: &'a Build,
-                          rules: &'b mut Rules<'a>,
-                          krate: &'a str,
-                          dep: &'a str,
-                          link: fn(&Build, &Compiler, &Compiler, &str))
-                          -> RuleBuilder<'a, 'b> {
-        let mut rule = rules.build(&krate, "path/to/nowhere");
-        rule.dep(move |s| {
-                if build.force_use_stage1(&s.compiler(), s.target) {
-                    s.host(&build.build).stage(1)
-                } else if s.host == build.build {
-                    s.name(dep)
-                } else {
-                    s.host(&build.build)
-                }
-            })
-            .run(move |s| {
-                if build.force_use_stage1(&s.compiler(), s.target) {
-                    link(build,
-                         &s.stage(1).host(&build.build).compiler(),
-                         &s.compiler(),
-                         s.target)
-                } else if s.host == build.build {
-                    link(build, &s.compiler(), &s.compiler(), s.target)
-                } else {
-                    link(build,
-                         &s.host(&build.build).compiler(),
-                         &s.compiler(),
-                         s.target)
-                }
-            });
-            rule
-    }
-
-    // Similar to the `libstd`, `libtest`, and `librustc` rules above, except
-    // these rules only represent the libraries being available in the sysroot,
-    // not the compiler itself. This is done as not all rules need a compiler in
-    // the sysroot, but may just need the libraries.
-    //
-    // All of these rules use the helper definition above.
-    crate_rule(build,
-               &mut rules,
-               "libstd-link",
-               "build-crate-std",
-               compile::std_link)
-        .dep(|s| s.name("startup-objects"))
-        .dep(|s| s.name("create-sysroot").target(s.host));
-    crate_rule(build,
-               &mut rules,
-               "libtest-link",
-               "build-crate-test",
-               compile::test_link)
-        .dep(|s| s.name("libstd-link"));
-    crate_rule(build,
-               &mut rules,
-               "librustc-link",
-               "build-crate-rustc-main",
-               compile::rustc_link)
-        .dep(|s| s.name("libtest-link"));
-
-    for (krate, path, _default) in krates("std") {
-        rules.build(&krate.build_step, path)
-             .dep(|s| s.name("startup-objects"))
-             .dep(move |s| s.name("rustc").host(&build.build).target(s.host))
-             .run(move |s| compile::std(build, s.target, &s.compiler()));
-    }
-    for (krate, path, _default) in krates("test") {
-        rules.build(&krate.build_step, path)
-             .dep(|s| s.name("libstd-link"))
-             .run(move |s| compile::test(build, s.target, &s.compiler()));
-    }
-    for (krate, path, _default) in krates("rustc-main") {
-        rules.build(&krate.build_step, path)
-             .dep(|s| s.name("libtest-link"))
-             .dep(move |s| s.name("llvm").host(&build.build).stage(0))
-             .dep(|s| s.name("may-run-build-script"))
-             .run(move |s| compile::rustc(build, s.target, &s.compiler()));
-    }
-
-    // Crates which have build scripts need to rely on this rule to ensure that
-    // the necessary prerequisites for a build script are linked and located in
-    // place.
-    rules.build("may-run-build-script", "path/to/nowhere")
-         .dep(move |s| {
-             s.name("libstd-link")
-              .host(&build.build)
-              .target(&build.build)
-         });
-    rules.build("startup-objects", "src/rtstartup")
-         .dep(|s| s.name("create-sysroot").target(s.host))
-         .run(move |s| compile::build_startup_objects(build, &s.compiler(), s.target));
-
-    // ========================================================================
-    // Test targets
-    //
-    // Various unit tests and tests suites we can run
-    {
-        let mut suite = |name, path, mode, dir| {
-            rules.test(name, path)
-                 .dep(|s| s.name("libtest"))
-                 .dep(|s| s.name("tool-compiletest").target(s.host).stage(0))
-                 .dep(|s| s.name("test-helpers"))
-                 .dep(|s| s.name("remote-copy-libs"))
-                 .default(mode != "pretty") // pretty tests don't run everywhere
-                 .run(move |s| {
-                     check::compiletest(build, &s.compiler(), s.target, mode, dir)
-                 });
-        };
-
-        suite("check-ui", "src/test/ui", "ui", "ui");
-        suite("check-rpass", "src/test/run-pass", "run-pass", "run-pass");
-        suite("check-cfail", "src/test/compile-fail", "compile-fail", "compile-fail");
-        suite("check-pfail", "src/test/parse-fail", "parse-fail", "parse-fail");
-        suite("check-rfail", "src/test/run-fail", "run-fail", "run-fail");
-        suite("check-rpass-valgrind", "src/test/run-pass-valgrind",
-              "run-pass-valgrind", "run-pass-valgrind");
-        suite("check-mir-opt", "src/test/mir-opt", "mir-opt", "mir-opt");
-        if build.config.codegen_tests {
-            suite("check-codegen", "src/test/codegen", "codegen", "codegen");
-        }
-        suite("check-codegen-units", "src/test/codegen-units", "codegen-units",
-              "codegen-units");
-        suite("check-incremental", "src/test/incremental", "incremental",
-              "incremental");
-    }
-
-    if build.build.contains("msvc") {
-        // nothing to do for debuginfo tests
-    } else {
-        rules.test("check-debuginfo-lldb", "src/test/debuginfo-lldb")
-             .dep(|s| s.name("libtest"))
-             .dep(|s| s.name("tool-compiletest").target(s.host).stage(0))
-             .dep(|s| s.name("test-helpers"))
-             .dep(|s| s.name("debugger-scripts"))
-             .run(move |s| check::compiletest(build, &s.compiler(), s.target,
-                                         "debuginfo-lldb", "debuginfo"));
-        rules.test("check-debuginfo-gdb", "src/test/debuginfo-gdb")
-             .dep(|s| s.name("libtest"))
-             .dep(|s| s.name("tool-compiletest").target(s.host).stage(0))
-             .dep(|s| s.name("test-helpers"))
-             .dep(|s| s.name("debugger-scripts"))
-             .dep(|s| s.name("remote-copy-libs"))
-             .run(move |s| check::compiletest(build, &s.compiler(), s.target,
-                                         "debuginfo-gdb", "debuginfo"));
-        let mut rule = rules.test("check-debuginfo", "src/test/debuginfo");
-        rule.default(true);
-        if build.build.contains("apple") {
-            rule.dep(|s| s.name("check-debuginfo-lldb"));
-        } else {
-            rule.dep(|s| s.name("check-debuginfo-gdb"));
-        }
-    }
-
-    rules.test("debugger-scripts", "src/etc/lldb_batchmode.py")
-         .run(move |s| dist::debugger_scripts(build, &build.sysroot(&s.compiler()),
-                                         s.target));
-
-    {
-        let mut suite = |name, path, mode, dir| {
-            rules.test(name, path)
-                 .dep(|s| s.name("librustc"))
-                 .dep(|s| s.name("test-helpers"))
-                 .dep(|s| s.name("tool-compiletest").target(s.host).stage(0))
-                 .default(mode != "pretty")
-                 .host(true)
-                 .run(move |s| {
-                     check::compiletest(build, &s.compiler(), s.target, mode, dir)
-                 });
-        };
-
-        suite("check-ui-full", "src/test/ui-fulldeps", "ui", "ui-fulldeps");
-        suite("check-rpass-full", "src/test/run-pass-fulldeps",
-              "run-pass", "run-pass-fulldeps");
-        suite("check-rfail-full", "src/test/run-fail-fulldeps",
-              "run-fail", "run-fail-fulldeps");
-        suite("check-cfail-full", "src/test/compile-fail-fulldeps",
-              "compile-fail", "compile-fail-fulldeps");
-        suite("check-rmake", "src/test/run-make", "run-make", "run-make");
-        suite("check-rustdoc", "src/test/rustdoc", "rustdoc", "rustdoc");
-        suite("check-pretty", "src/test/pretty", "pretty", "pretty");
-        suite("check-pretty-rpass", "src/test/run-pass/pretty", "pretty",
-              "run-pass");
-        suite("check-pretty-rfail", "src/test/run-fail/pretty", "pretty",
-              "run-fail");
-        suite("check-pretty-valgrind", "src/test/run-pass-valgrind/pretty", "pretty",
-              "run-pass-valgrind");
-        suite("check-pretty-rpass-full", "src/test/run-pass-fulldeps/pretty",
-              "pretty", "run-pass-fulldeps");
-        suite("check-pretty-rfail-full", "src/test/run-fail-fulldeps/pretty",
-              "pretty", "run-fail-fulldeps");
-    }
-
-    for (krate, path, _default) in krates("std") {
-        rules.test(&krate.test_step, path)
-             .dep(|s| s.name("libtest"))
-             .dep(|s| s.name("remote-copy-libs"))
-             .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                        Mode::Libstd, TestKind::Test,
-                                        Some(&krate.name)));
-    }
-    rules.test("check-std-all", "path/to/nowhere")
-         .dep(|s| s.name("libtest"))
-         .dep(|s| s.name("remote-copy-libs"))
-         .default(true)
-         .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                    Mode::Libstd, TestKind::Test, None));
-
-    // std benchmarks
-    for (krate, path, _default) in krates("std") {
-        rules.bench(&krate.bench_step, path)
-             .dep(|s| s.name("libtest"))
-             .dep(|s| s.name("remote-copy-libs"))
-             .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                        Mode::Libstd, TestKind::Bench,
-                                        Some(&krate.name)));
-    }
-    rules.bench("bench-std-all", "path/to/nowhere")
-         .dep(|s| s.name("libtest"))
-         .dep(|s| s.name("remote-copy-libs"))
-         .default(true)
-         .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                    Mode::Libstd, TestKind::Bench, None));
-
-    for (krate, path, _default) in krates("test") {
-        rules.test(&krate.test_step, path)
-             .dep(|s| s.name("libtest"))
-             .dep(|s| s.name("remote-copy-libs"))
-             .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                        Mode::Libtest, TestKind::Test,
-                                        Some(&krate.name)));
-    }
-    rules.test("check-test-all", "path/to/nowhere")
-         .dep(|s| s.name("libtest"))
-         .dep(|s| s.name("remote-copy-libs"))
-         .default(true)
-         .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                    Mode::Libtest, TestKind::Test, None));
-    for (krate, path, _default) in krates("rustc-main") {
-        rules.test(&krate.test_step, path)
-             .dep(|s| s.name("librustc"))
-             .dep(|s| s.name("remote-copy-libs"))
-             .host(true)
-             .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                        Mode::Librustc, TestKind::Test,
-                                        Some(&krate.name)));
-    }
-    rules.test("check-rustc-all", "path/to/nowhere")
-         .dep(|s| s.name("librustc"))
-         .dep(|s| s.name("remote-copy-libs"))
-         .default(true)
-         .host(true)
-         .run(move |s| check::krate(build, &s.compiler(), s.target,
-                                    Mode::Librustc, TestKind::Test, None));
-
-    rules.test("check-linkchecker", "src/tools/linkchecker")
-         .dep(|s| s.name("tool-linkchecker").stage(0))
-         .dep(|s| s.name("default:doc"))
-         .default(build.config.docs)
-         .host(true)
-         .run(move |s| check::linkcheck(build, s.target));
-    rules.test("check-cargotest", "src/tools/cargotest")
-         .dep(|s| s.name("tool-cargotest").stage(0))
-         .dep(|s| s.name("librustc"))
-         .host(true)
-         .run(move |s| check::cargotest(build, s.stage, s.target));
-    rules.test("check-cargo", "src/tools/cargo")
-         .dep(|s| s.name("tool-cargo"))
-         .host(true)
-         .run(move |s| check::cargo(build, s.stage, s.target));
-    rules.test("check-rls", "src/tools/rls")
-         .dep(|s| s.name("tool-rls"))
-         .host(true)
-         .run(move |s| check::rls(build, s.stage, s.target));
-    rules.test("check-tidy", "src/tools/tidy")
-         .dep(|s| s.name("tool-tidy").stage(0))
-         .default(true)
-         .host(true)
-         .only_build(true)
-         .run(move |s| check::tidy(build, s.target));
-    rules.test("check-error-index", "src/tools/error_index_generator")
-         .dep(|s| s.name("libstd"))
-         .dep(|s| s.name("tool-error-index").host(s.host).stage(0))
-         .default(true)
-         .host(true)
-         .run(move |s| check::error_index(build, &s.compiler()));
-    rules.test("check-docs", "src/doc")
-         .dep(|s| s.name("libtest"))
-         .default(true)
-         .host(true)
-         .run(move |s| check::docs(build, &s.compiler()));
-    rules.test("check-distcheck", "distcheck")
-         .dep(|s| s.name("dist-plain-source-tarball"))
-         .dep(|s| s.name("dist-src"))
-         .run(move |_| check::distcheck(build));
-
-    rules.build("test-helpers", "src/rt/rust_test_helpers.c")
-         .run(move |s| native::test_helpers(build, s.target));
-    rules.build("openssl", "path/to/nowhere")
-         .run(move |s| native::openssl(build, s.target));
-
-    // Some test suites are run inside emulators or on remote devices, and most
-    // of our test binaries are linked dynamically which means we need to ship
-    // the standard library and such to the emulator ahead of time. This step
-    // represents this and is a dependency of all test suites.
-    //
-    // Most of the time this step is a noop (the `check::emulator_copy_libs`
-    // only does work if necessary). For some steps such as shipping data to
-    // QEMU we have to build our own tools so we've got conditional dependencies
-    // on those programs as well. Note that the remote test client is built for
-    // the build target (us) and the server is built for the target.
-    rules.test("remote-copy-libs", "path/to/nowhere")
-         .dep(|s| s.name("libtest"))
-         .dep(move |s| {
-             if build.remote_tested(s.target) {
-                s.name("tool-remote-test-client").target(s.host).stage(0)
-             } else {
-                 Step::noop()
-             }
-         })
-         .dep(move |s| {
-             if build.remote_tested(s.target) {
-                s.name("tool-remote-test-server")
-             } else {
-                 Step::noop()
-             }
-         })
-         .run(move |s| check::remote_copy_libs(build, &s.compiler(), s.target));
-
-    rules.test("check-bootstrap", "src/bootstrap")
-         .default(true)
-         .host(true)
-         .only_build(true)
-         .run(move |_| check::bootstrap(build));
-
-    // ========================================================================
-    // Build tools
-    //
-    // Tools used during the build system but not shipped
-    rules.build("tool-rustbook", "src/tools/rustbook")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("librustc-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "rustbook"));
-    rules.build("tool-error-index", "src/tools/error_index_generator")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("librustc-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "error_index_generator"));
-    rules.build("tool-unstable-book-gen", "src/tools/unstable-book-gen")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "unstable-book-gen"));
-    rules.build("tool-tidy", "src/tools/tidy")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "tidy"));
-    rules.build("tool-linkchecker", "src/tools/linkchecker")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "linkchecker"));
-    rules.build("tool-cargotest", "src/tools/cargotest")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "cargotest"));
-    rules.build("tool-compiletest", "src/tools/compiletest")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libtest-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "compiletest"));
-    rules.build("tool-build-manifest", "src/tools/build-manifest")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "build-manifest"));
-    rules.build("tool-remote-test-server", "src/tools/remote-test-server")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "remote-test-server"));
-    rules.build("tool-remote-test-client", "src/tools/remote-test-client")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "remote-test-client"));
-    rules.build("tool-rust-installer", "src/tools/rust-installer")
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .run(move |s| compile::tool(build, s.stage, s.target, "rust-installer"));
-    rules.build("tool-cargo", "src/tools/cargo")
-         .host(true)
-         .default(build.config.extended)
-         .dep(|s| s.name("maybe-clean-tools"))
-         .dep(|s| s.name("libstd-tool"))
-         .dep(|s| s.stage(0).host(s.target).name("openssl"))
-         .dep(move |s| {
-             // Cargo depends on procedural macros, which requires a full host
-             // compiler to be available, so we need to depend on that.
-             s.name("librustc-link")
-              .target(&build.build)
-              .host(&build.build)
-         })
-         .run(move |s| compile::tool(build, s.stage, s.target, "cargo"));
-    rules.build("tool-rls", "src/tools/rls")
-         .host(true)
-         .default(build.config.extended)
-         .dep(|s| s.name("librustc-tool"))
-         .dep(|s| s.stage(0).host(s.target).name("openssl"))
-         .dep(move |s| {
-             // rls, like cargo, uses procedural macros
-             s.name("librustc-link")
-              .target(&build.build)
-              .host(&build.build)
-         })
-         .run(move |s| compile::tool(build, s.stage, s.target, "rls"));
-
-    // "pseudo rule" which represents completely cleaning out the tools dir in
-    // one stage. This needs to happen whenever a dependency changes (e.g.
-    // libstd, libtest, librustc) and all of the tool compilations above will
-    // be sequenced after this rule.
-    rules.build("maybe-clean-tools", "path/to/nowhere")
-         .after("librustc-tool")
-         .after("libtest-tool")
-         .after("libstd-tool");
-
-    rules.build("librustc-tool", "path/to/nowhere")
-         .dep(|s| s.name("librustc"))
-         .run(move |s| compile::maybe_clean_tools(build, s.stage, s.target, Mode::Librustc));
-    rules.build("libtest-tool", "path/to/nowhere")
-         .dep(|s| s.name("libtest"))
-         .run(move |s| compile::maybe_clean_tools(build, s.stage, s.target, Mode::Libtest));
-    rules.build("libstd-tool", "path/to/nowhere")
-         .dep(|s| s.name("libstd"))
-         .run(move |s| compile::maybe_clean_tools(build, s.stage, s.target, Mode::Libstd));
-
-    // ========================================================================
-    // Documentation targets
-    rules.doc("doc-book", "src/doc/book")
-         .dep(move |s| {
-             s.name("tool-rustbook")
-              .host(&build.build)
-              .target(&build.build)
-              .stage(0)
-         })
-         .default(build.config.docs)
-         .run(move |s| doc::book(build, s.target, "book"));
-    rules.doc("doc-nomicon", "src/doc/nomicon")
-         .dep(move |s| {
-             s.name("tool-rustbook")
-              .host(&build.build)
-              .target(&build.build)
-              .stage(0)
-         })
-         .default(build.config.docs)
-         .run(move |s| doc::rustbook(build, s.target, "nomicon"));
-    rules.doc("doc-reference", "src/doc/reference")
-         .dep(move |s| {
-             s.name("tool-rustbook")
-              .host(&build.build)
-              .target(&build.build)
-              .stage(0)
-         })
-         .default(build.config.docs)
-         .run(move |s| doc::rustbook(build, s.target, "reference"));
-    rules.doc("doc-unstable-book", "src/doc/unstable-book")
-         .dep(move |s| {
-             s.name("tool-rustbook")
-              .host(&build.build)
-              .target(&build.build)
-              .stage(0)
-         })
-         .dep(move |s| s.name("doc-unstable-book-gen"))
-         .default(build.config.docs)
-         .run(move |s| doc::rustbook_src(build,
-                                         s.target,
-                                         "unstable-book",
-                                         &build.md_doc_out(s.target)));
-    rules.doc("doc-standalone", "src/doc")
-         .dep(move |s| {
-             s.name("rustc")
-              .host(&build.build)
-              .target(&build.build)
-              .stage(0)
-         })
-         .default(build.config.docs)
-         .run(move |s| doc::standalone(build, s.target));
-    rules.doc("doc-error-index", "src/tools/error_index_generator")
-         .dep(move |s| s.name("tool-error-index").target(&build.build).stage(0))
-         .dep(move |s| s.name("librustc-link"))
-         .default(build.config.docs)
-         .host(true)
-         .run(move |s| doc::error_index(build, s.target));
-    rules.doc("doc-unstable-book-gen", "src/tools/unstable-book-gen")
-         .dep(move |s| {
-             s.name("tool-unstable-book-gen")
-              .host(&build.build)
-              .target(&build.build)
-              .stage(0)
-         })
-         .dep(move |s| s.name("libstd-link"))
-         .default(build.config.docs)
-         .host(true)
-         .run(move |s| doc::unstable_book_gen(build, s.target));
-    for (krate, path, default) in krates("std") {
-        rules.doc(&krate.doc_step, path)
-             .dep(|s| s.name("libstd-link"))
-             .default(default && build.config.docs)
-             .run(move |s| doc::std(build, s.stage, s.target));
-    }
-    for (krate, path, default) in krates("test") {
-        rules.doc(&krate.doc_step, path)
-             .dep(|s| s.name("libtest-link"))
-             // Needed so rustdoc generates relative links to std.
-             .dep(|s| s.name("doc-crate-std"))
-             .default(default && build.config.compiler_docs)
-             .run(move |s| doc::test(build, s.stage, s.target));
-    }
-    for (krate, path, default) in krates("rustc-main") {
-        rules.doc(&krate.doc_step, path)
-             .dep(|s| s.name("librustc-link"))
-             // Needed so rustdoc generates relative links to std.
-             .dep(|s| s.name("doc-crate-std"))
-             .host(true)
-             .default(default && build.config.docs)
-             .run(move |s| doc::rustc(build, s.stage, s.target));
-    }
-
-    // ========================================================================
-    // Distribution targets
-    rules.dist("dist-rustc", "src/librustc")
-         .dep(move |s| s.name("rustc").host(&build.build))
-         .host(true)
-         .only_host_build(true)
-         .default(true)
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::rustc(build, s.stage, s.target));
-    rules.dist("dist-std", "src/libstd")
-         .dep(move |s| {
-             // We want to package up as many target libraries as possible
-             // for the `rust-std` package, so if this is a host target we
-             // depend on librustc and otherwise we just depend on libtest.
-             if build.config.host.iter().any(|t| t == s.target) {
-                 s.name("librustc-link")
-             } else {
-                 s.name("libtest-link")
-             }
-         })
-         .default(true)
-         .only_host_build(true)
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::std(build, &s.compiler(), s.target));
-    rules.dist("dist-mingw", "path/to/nowhere")
-         .default(true)
-         .only_host_build(true)
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| {
-             if s.target.contains("pc-windows-gnu") {
-                 dist::mingw(build, s.target)
-             }
-         });
-    rules.dist("dist-plain-source-tarball", "src")
-         .default(build.config.rust_dist_src)
-         .host(true)
-         .only_build(true)
-         .only_host_build(true)
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |_| dist::plain_source_tarball(build));
-    rules.dist("dist-src", "src")
-         .default(true)
-         .host(true)
-         .only_build(true)
-         .only_host_build(true)
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |_| dist::rust_src(build));
-    rules.dist("dist-docs", "src/doc")
-         .default(true)
-         .only_host_build(true)
-         .dep(|s| s.name("default:doc"))
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::docs(build, s.stage, s.target));
-    rules.dist("dist-analysis", "analysis")
-         .default(build.config.extended)
-         .dep(|s| s.name("dist-std"))
-         .only_host_build(true)
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::analysis(build, &s.compiler(), s.target));
-    rules.dist("dist-rls", "rls")
-         .host(true)
-         .only_host_build(true)
-         .dep(|s| s.name("tool-rls"))
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::rls(build, s.stage, s.target));
-    rules.dist("dist-cargo", "cargo")
-         .host(true)
-         .only_host_build(true)
-         .dep(|s| s.name("tool-cargo"))
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::cargo(build, s.stage, s.target));
-    rules.dist("dist-extended", "extended")
-         .default(build.config.extended)
-         .host(true)
-         .only_host_build(true)
-         .dep(|d| d.name("dist-std"))
-         .dep(|d| d.name("dist-rustc"))
-         .dep(|d| d.name("dist-mingw"))
-         .dep(|d| d.name("dist-docs"))
-         .dep(|d| d.name("dist-cargo"))
-         .dep(|d| d.name("dist-rls"))
-         .dep(|d| d.name("dist-analysis"))
-         .dep(move |s| tool_rust_installer(build, s))
-         .run(move |s| dist::extended(build, s.stage, s.target));
-
-    rules.dist("dist-sign", "hash-and-sign")
-         .host(true)
-         .only_build(true)
-         .only_host_build(true)
-         .dep(move |s| s.name("tool-build-manifest").target(&build.build).stage(0))
-         .run(move |_| dist::hash_and_sign(build));
-
-    rules.install("install-docs", "src/doc")
-         .default(build.config.docs)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-docs"))
-         .run(move |s| install::Installer::new(build).install_docs(s.stage, s.target));
-    rules.install("install-std", "src/libstd")
-         .default(true)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-std"))
-         .run(move |s| install::Installer::new(build).install_std(s.stage));
-    rules.install("install-cargo", "cargo")
-         .default(build.config.extended)
-         .host(true)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-cargo"))
-         .run(move |s| install::Installer::new(build).install_cargo(s.stage, s.target));
-    rules.install("install-rls", "rls")
-         .default(build.config.extended)
-         .host(true)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-rls"))
-         .run(move |s| install::Installer::new(build).install_rls(s.stage, s.target));
-    rules.install("install-analysis", "analysis")
-         .default(build.config.extended)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-analysis"))
-         .run(move |s| install::Installer::new(build).install_analysis(s.stage, s.target));
-    rules.install("install-src", "src")
-         .default(build.config.extended)
-         .host(true)
-         .only_build(true)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-src"))
-         .run(move |s| install::Installer::new(build).install_src(s.stage));
-    rules.install("install-rustc", "src/librustc")
-         .default(true)
-         .host(true)
-         .only_host_build(true)
-         .dep(|s| s.name("dist-rustc"))
-         .run(move |s| install::Installer::new(build).install_rustc(s.stage, s.target));
-
-    rules.verify();
-    return rules;
-
-    /// Helper to depend on a stage0 build-only rust-installer tool.
-    fn tool_rust_installer<'a>(build: &'a Build, step: &Step<'a>) -> Step<'a> {
-        step.name("tool-rust-installer")
-            .host(&build.build)
-            .target(&build.build)
-            .stage(0)
-    }
-}
-
-#[derive(PartialEq, Eq, Hash, Clone, Debug)]
-struct Step<'a> {
-    /// Human readable name of the rule this step is executing. Possible names
-    /// are all defined above in `build_rules`.
-    name: &'a str,
-
-    /// The stage this step is executing in. This is typically 0, 1, or 2.
-    stage: u32,
-
-    /// This step will likely involve a compiler, and the target that compiler
-    /// itself is built for is called the host, this variable. Typically this is
-    /// the target of the build machine itself.
-    host: &'a str,
-
-    /// The target that this step represents generating. If you're building a
-    /// standard library for a new suite of targets, for example, this'll be set
-    /// to those targets.
-    target: &'a str,
-}
-
-impl<'a> Step<'a> {
-    fn noop() -> Step<'a> {
-        Step { name: "", stage: 0, host: "", target: "" }
-    }
-
-    /// Creates a new step which is the same as this, except has a new name.
-    fn name(&self, name: &'a str) -> Step<'a> {
-        Step { name: name, ..*self }
-    }
-
-    /// Creates a new step which is the same as this, except has a new stage.
-    fn stage(&self, stage: u32) -> Step<'a> {
-        Step { stage: stage, ..*self }
-    }
-
-    /// Creates a new step which is the same as this, except has a new host.
-    fn host(&self, host: &'a str) -> Step<'a> {
-        Step { host: host, ..*self }
-    }
-
-    /// Creates a new step which is the same as this, except has a new target.
-    fn target(&self, target: &'a str) -> Step<'a> {
-        Step { target: target, ..*self }
-    }
-
-    /// Returns the `Compiler` structure that this step corresponds to.
-    fn compiler(&self) -> Compiler<'a> {
-        Compiler::new(self.stage, self.host)
-    }
-}
-
-struct Rule<'a> {
-    /// The human readable name of this target, defined in `build_rules`.
-    name: &'a str,
-
-    /// The path associated with this target, used in the `./x.py` driver for
-    /// easy and ergonomic specification of what to do.
-    path: &'a str,
-
-    /// The "kind" of top-level command that this rule is associated with, only
-    /// relevant if this is a default rule.
-    kind: Kind,
-
-    /// List of dependencies this rule has. Each dependency is a function from a
-    /// step that's being executed to another step that should be executed.
-    deps: Vec<Box<Fn(&Step<'a>) -> Step<'a> + 'a>>,
-
-    /// How to actually execute this rule. Takes a step with contextual
-    /// information and then executes it.
-    run: Box<Fn(&Step<'a>) + 'a>,
-
-    /// Whether or not this is a "default" rule. That basically means that if
-    /// you run, for example, `./x.py test` whether it's included or not.
-    default: bool,
-
-    /// Whether or not this is a "host" rule, or in other words whether this is
-    /// only intended for compiler hosts and not for targets that are being
-    /// generated.
-    host: bool,
-
-    /// Whether this rule is only for steps where the host is the build triple,
-    /// not anything in hosts or targets.
-    only_host_build: bool,
-
-    /// Whether this rule is only for the build triple, not anything in hosts or
-    /// targets.
-    only_build: bool,
-
-    /// A list of "order only" dependencies. This rules does not actually
-    /// depend on these rules, but if they show up in the dependency graph then
-    /// this rule must be executed after all these rules.
-    after: Vec<&'a str>,
-}
-
-#[derive(PartialEq)]
-enum Kind {
-    Build,
-    Test,
-    Bench,
-    Dist,
-    Doc,
-    Install,
-}
-
-impl<'a> Rule<'a> {
-    fn new(name: &'a str, path: &'a str, kind: Kind) -> Rule<'a> {
-        Rule {
-            name: name,
-            deps: Vec::new(),
-            run: Box::new(|_| ()),
-            path: path,
-            kind: kind,
-            default: false,
-            host: false,
-            only_host_build: false,
-            only_build: false,
-            after: Vec::new(),
-        }
-    }
-}
-
-/// Builder pattern returned from the various methods on `Rules` which will add
-/// the rule to the internal list on `Drop`.
-struct RuleBuilder<'a: 'b, 'b> {
-    rules: &'b mut Rules<'a>,
-    rule: Rule<'a>,
-}
-
-impl<'a, 'b> RuleBuilder<'a, 'b> {
-    fn dep<F>(&mut self, f: F) -> &mut Self
-        where F: Fn(&Step<'a>) -> Step<'a> + 'a,
-    {
-        self.rule.deps.push(Box::new(f));
-        self
-    }
-
-    fn after(&mut self, step: &'a str) -> &mut Self {
-        self.rule.after.push(step);
-        self
-    }
-
-    fn run<F>(&mut self, f: F) -> &mut Self
-        where F: Fn(&Step<'a>) + 'a,
-    {
-        self.rule.run = Box::new(f);
-        self
-    }
-
-    fn default(&mut self, default: bool) -> &mut Self {
-        self.rule.default = default;
-        self
-    }
-
-    fn host(&mut self, host: bool) -> &mut Self {
-        self.rule.host = host;
-        self
-    }
-
-    fn only_build(&mut self, only_build: bool) -> &mut Self {
-        self.rule.only_build = only_build;
-        self
-    }
-
-    fn only_host_build(&mut self, only_host_build: bool) -> &mut Self {
-        self.rule.only_host_build = only_host_build;
-        self
-    }
-}
-
-impl<'a, 'b> Drop for RuleBuilder<'a, 'b> {
-    fn drop(&mut self) {
-        let rule = mem::replace(&mut self.rule, Rule::new("", "", Kind::Build));
-        let prev = self.rules.rules.insert(rule.name, rule);
-        if let Some(prev) = prev {
-            panic!("duplicate rule named: {}", prev.name);
-        }
-    }
-}
-
-pub struct Rules<'a> {
-    build: &'a Build,
-    sbuild: Step<'a>,
-    rules: BTreeMap<&'a str, Rule<'a>>,
-}
-
-impl<'a> Rules<'a> {
-    fn new(build: &'a Build) -> Rules<'a> {
-        Rules {
-            build: build,
-            sbuild: Step {
-                stage: build.flags.stage.unwrap_or(2),
-                target: &build.build,
-                host: &build.build,
-                name: "",
-            },
-            rules: BTreeMap::new(),
-        }
-    }
-
-    /// Creates a new rule of `Kind::Build` with the specified human readable
-    /// name and path associated with it.
-    ///
-    /// The builder returned should be configured further with information such
-    /// as how to actually run this rule.
-    fn build<'b>(&'b mut self, name: &'a str, path: &'a str)
-                 -> RuleBuilder<'a, 'b> {
-        self.rule(name, path, Kind::Build)
-    }
-
-    /// Same as `build`, but for `Kind::Test`.
-    fn test<'b>(&'b mut self, name: &'a str, path: &'a str)
-                -> RuleBuilder<'a, 'b> {
-        self.rule(name, path, Kind::Test)
-    }
-
-    /// Same as `build`, but for `Kind::Bench`.
-    fn bench<'b>(&'b mut self, name: &'a str, path: &'a str)
-                -> RuleBuilder<'a, 'b> {
-        self.rule(name, path, Kind::Bench)
-    }
-
-    /// Same as `build`, but for `Kind::Doc`.
-    fn doc<'b>(&'b mut self, name: &'a str, path: &'a str)
-               -> RuleBuilder<'a, 'b> {
-        self.rule(name, path, Kind::Doc)
-    }
-
-    /// Same as `build`, but for `Kind::Dist`.
-    fn dist<'b>(&'b mut self, name: &'a str, path: &'a str)
-                -> RuleBuilder<'a, 'b> {
-        self.rule(name, path, Kind::Dist)
-    }
-
-    /// Same as `build`, but for `Kind::Install`.
-    fn install<'b>(&'b mut self, name: &'a str, path: &'a str)
-                -> RuleBuilder<'a, 'b> {
-        self.rule(name, path, Kind::Install)
-    }
-
-    fn rule<'b>(&'b mut self,
-                name: &'a str,
-                path: &'a str,
-                kind: Kind) -> RuleBuilder<'a, 'b> {
-        RuleBuilder {
-            rules: self,
-            rule: Rule::new(name, path, kind),
-        }
-    }
-
-    /// Verify the dependency graph defined by all our rules are correct, e.g.
-    /// everything points to a valid something else.
-    fn verify(&self) {
-        for rule in self.rules.values() {
-            for dep in rule.deps.iter() {
-                let dep = dep(&self.sbuild.name(rule.name));
-                if self.rules.contains_key(&dep.name) || dep.name.starts_with("default:") {
-                    continue
-                }
-                if dep == Step::noop() {
-                    continue
-                }
-                panic!("\
-
-invalid rule dependency graph detected, was a rule added and maybe typo'd?
-
-    `{}` depends on `{}` which does not exist
-
-", rule.name, dep.name);
-            }
-        }
-    }
-
-    pub fn get_help(&self, command: &str) -> Option<String> {
-        let kind = match command {
-            "build" => Kind::Build,
-            "doc" => Kind::Doc,
-            "test" => Kind::Test,
-            "bench" => Kind::Bench,
-            "dist" => Kind::Dist,
-            "install" => Kind::Install,
-            _ => return None,
-        };
-        let rules = self.rules.values().filter(|r| r.kind == kind);
-        let rules = rules.filter(|r| !r.path.contains("nowhere"));
-        let mut rules = rules.collect::<Vec<_>>();
-        rules.sort_by_key(|r| r.path);
-
-        let mut help_string = String::from("Available paths:\n");
-        for rule in rules {
-            help_string.push_str(format!("    ./x.py {} {}\n", command, rule.path).as_str());
-        }
-        Some(help_string)
-    }
-
-    /// Construct the top-level build steps that we're going to be executing,
-    /// given the subcommand that our build is performing.
-    fn plan(&self) -> Vec<Step<'a>> {
-        // Ok, the logic here is pretty subtle, and involves quite a few
-        // conditionals. The basic idea here is to:
-        //
-        // 1. First, filter all our rules to the relevant ones. This means that
-        //    the command specified corresponds to one of our `Kind` variants,
-        //    and we filter all rules based on that.
-        //
-        // 2. Next, we determine which rules we're actually executing. If a
-        //    number of path filters were specified on the command line we look
-        //    for those, otherwise we look for anything tagged `default`.
-        //    Here we also compute the priority of each rule based on how early
-        //    in the command line the matching path filter showed up.
-        //
-        // 3. Finally, we generate some steps with host and target information.
-        //
-        // The last step is by far the most complicated and subtle. The basic
-        // thinking here is that we want to take the cartesian product of
-        // specified hosts and targets and build rules with that. The list of
-        // hosts and targets, if not specified, come from the how this build was
-        // configured. If the rule we're looking at is a host-only rule the we
-        // ignore the list of targets and instead consider the list of hosts
-        // also the list of targets.
-        //
-        // Once the host and target lists are generated we take the cartesian
-        // product of the two and then create a step based off them. Note that
-        // the stage each step is associated was specified with the `--step`
-        // flag on the command line.
-        let (kind, paths) = match self.build.flags.cmd {
-            Subcommand::Build { ref paths } => (Kind::Build, &paths[..]),
-            Subcommand::Doc { ref paths } => (Kind::Doc, &paths[..]),
-            Subcommand::Test { ref paths, .. } => (Kind::Test, &paths[..]),
-            Subcommand::Bench { ref paths, .. } => (Kind::Bench, &paths[..]),
-            Subcommand::Dist { ref paths } => (Kind::Dist, &paths[..]),
-            Subcommand::Install { ref paths } => (Kind::Install, &paths[..]),
-            Subcommand::Clean => panic!(),
-        };
-
-        let mut rules: Vec<_> = self.rules.values().filter_map(|rule| {
-            if rule.kind != kind {
-                return None;
-            }
-
-            if paths.len() == 0 && rule.default {
-                Some((rule, 0))
-            } else {
-                paths.iter()
-                     .position(|path| path.ends_with(rule.path))
-                     .map(|priority| (rule, priority))
-            }
-        }).collect();
-
-        if rules.is_empty() &&
-           !paths.get(0).unwrap_or(&PathBuf::new())
-                 .ends_with("nonexistent/path/to/trigger/cargo/metadata") {
-            println!("\nNothing to run...\n");
-            process::exit(1);
-        }
-
-        rules.sort_by_key(|&(_, priority)| priority);
-
-        rules.into_iter().flat_map(|(rule, _)| {
-            let hosts = if rule.only_host_build || rule.only_build {
-                self.build.build_slice()
-            } else {
-                &self.build.hosts
-            };
-            // Determine the actual targets participating in this rule.
-            // NOTE: We should keep the full projection from build triple to
-            // the hosts for the dist steps, now that the hosts array above is
-            // truncated to avoid duplication of work in that case. Therefore
-            // the original non-shadowed hosts array is used below.
-            let arr = if rule.host {
-                // If --target was specified but --host wasn't specified,
-                // don't run any host-only tests.
-                if self.build.flags.host.len() > 0 {
-                    &self.build.hosts
-                } else if self.build.flags.target.len() > 0 {
-                    &[]
-                } else if rule.only_build {
-                    self.build.build_slice()
-                } else {
-                    &self.build.hosts
-                }
-            } else {
-                &self.build.targets
-            };
-
-            hosts.iter().flat_map(move |host| {
-                arr.iter().map(move |target| {
-                    self.sbuild.name(rule.name).target(target).host(host)
-                })
-            })
-        }).collect()
-    }
-
-    /// Execute all top-level targets indicated by `steps`.
-    ///
-    /// This will take the list returned by `plan` and then execute each step
-    /// along with all required dependencies as it goes up the chain.
-    fn run(&self, steps: &[Step<'a>]) {
-        self.build.verbose("bootstrap top targets:");
-        for step in steps.iter() {
-            self.build.verbose(&format!("\t{:?}", step));
-        }
-
-        // Using `steps` as the top-level targets, make a topological ordering
-        // of what we need to do.
-        let order = self.expand(steps);
-
-        // Print out what we're doing for debugging
-        self.build.verbose("bootstrap build plan:");
-        for step in order.iter() {
-            self.build.verbose(&format!("\t{:?}", step));
-        }
-
-        // And finally, iterate over everything and execute it.
-        for step in order.iter() {
-            if self.build.flags.keep_stage.map_or(false, |s| step.stage <= s) {
-                self.build.verbose(&format!("keeping step {:?}", step));
-                continue;
-            }
-            self.build.verbose(&format!("executing step {:?}", step));
-            (self.rules[step.name].run)(step);
-        }
-
-        // Check for postponed failures from `test --no-fail-fast`.
-        let failures = self.build.delayed_failures.get();
-        if failures > 0 {
-            println!("\n{} command(s) did not execute successfully.\n", failures);
-            process::exit(1);
-        }
-    }
-
-    /// From the top level targets `steps` generate a topological ordering of
-    /// all steps needed to run those steps.
-    fn expand(&self, steps: &[Step<'a>]) -> Vec<Step<'a>> {
-        // First up build a graph of steps and their dependencies. The `nodes`
-        // map is a map from step to a unique number. The `edges` map is a
-        // map from these unique numbers to a list of other numbers,
-        // representing dependencies.
-        let mut nodes = HashMap::new();
-        nodes.insert(Step::noop(), 0);
-        let mut edges = HashMap::new();
-        edges.insert(0, HashSet::new());
-        for step in steps {
-            self.build_graph(step.clone(), &mut nodes, &mut edges);
-        }
-
-        // Now that we've built up the actual dependency graph, draw more
-        // dependency edges to satisfy the `after` dependencies field for each
-        // rule.
-        self.satisfy_after_deps(&nodes, &mut edges);
-
-        // And finally, perform a topological sort to return a list of steps to
-        // execute.
-        let mut order = Vec::new();
-        let mut visited = HashSet::new();
-        visited.insert(0);
-        let idx_to_node = nodes.iter().map(|p| (*p.1, p.0)).collect::<HashMap<_, _>>();
-        for idx in 0..nodes.len() {
-            self.topo_sort(idx, &idx_to_node, &edges, &mut visited, &mut order);
-        }
-        order
-    }
-
-    /// Builds the dependency graph rooted at `step`.
-    ///
-    /// The `nodes` and `edges` maps are filled out according to the rule
-    /// described by `step.name`.
-    fn build_graph(&self,
-                   step: Step<'a>,
-                   nodes: &mut HashMap<Step<'a>, usize>,
-                   edges: &mut HashMap<usize, HashSet<usize>>) -> usize {
-        use std::collections::hash_map::Entry;
-
-        let idx = nodes.len();
-        match nodes.entry(step.clone()) {
-            Entry::Vacant(e) => { e.insert(idx); }
-            Entry::Occupied(e) => return *e.get(),
-        }
-
-        let mut deps = Vec::new();
-        for dep in self.rules[step.name].deps.iter() {
-            let dep = dep(&step);
-            if dep.name.starts_with("default:") {
-                let kind = match &dep.name[8..] {
-                    "doc" => Kind::Doc,
-                    "dist" => Kind::Dist,
-                    kind => panic!("unknown kind: `{}`", kind),
-                };
-                let host = self.build.config.host.iter().any(|h| h == dep.target);
-                let rules = self.rules.values().filter(|r| r.default);
-                for rule in rules.filter(|r| r.kind == kind && (!r.host || host)) {
-                    deps.push(self.build_graph(dep.name(rule.name), nodes, edges));
-                }
-            } else {
-                deps.push(self.build_graph(dep, nodes, edges));
-            }
-        }
-
-        edges.entry(idx).or_insert(HashSet::new()).extend(deps);
-        idx
-    }
-
-    /// Given a dependency graph with a finished list of `nodes`, fill out more
-    /// dependency `edges`.
-    ///
-    /// This is the step which satisfies all `after` listed dependencies in
-    /// `Rule` above.
-    fn satisfy_after_deps(&self,
-                          nodes: &HashMap<Step<'a>, usize>,
-                          edges: &mut HashMap<usize, HashSet<usize>>) {
-        // Reverse map from the name of a step to the node indices that it
-        // appears at.
-        let mut name_to_idx = HashMap::new();
-        for (step, &idx) in nodes {
-            name_to_idx.entry(step.name).or_insert(Vec::new()).push(idx);
-        }
-
-        for (step, idx) in nodes {
-            if *step == Step::noop() {
-                continue
-            }
-            for after in self.rules[step.name].after.iter() {
-                // This is the critical piece of an `after` dependency. If the
-                // dependency isn't actually in our graph then no edge is drawn,
-                // only if it's already present do we draw the edges.
-                if let Some(idxs) = name_to_idx.get(after) {
-                    edges.get_mut(idx).unwrap()
-                         .extend(idxs.iter().cloned());
-                }
-            }
-        }
-    }
-
-    fn topo_sort(&self,
-                 cur: usize,
-                 nodes: &HashMap<usize, &Step<'a>>,
-                 edges: &HashMap<usize, HashSet<usize>>,
-                 visited: &mut HashSet<usize>,
-                 order: &mut Vec<Step<'a>>) {
-        if !visited.insert(cur) {
-            return
-        }
-        for dep in edges[&cur].iter() {
-            self.topo_sort(*dep, nodes, edges, visited, order);
-        }
-        order.push(nodes[&cur].clone());
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use std::env;
-
-    use Build;
-    use config::Config;
-    use flags::Flags;
-
-    fn build(args: &[&str],
-             extra_host: &[&str],
-             extra_target: &[&str]) -> Build {
-        build_(args, extra_host, extra_target, true)
-    }
-
-    fn build_(args: &[&str],
-              extra_host: &[&str],
-              extra_target: &[&str],
-              docs: bool) -> Build {
-        let mut args = args.iter().map(|s| s.to_string()).collect::<Vec<_>>();
-        args.push("--build".to_string());
-        args.push("A".to_string());
-        let flags = Flags::parse(&args);
-
-        let mut config = Config::default();
-        config.docs = docs;
-        config.build = "A".to_string();
-        config.host = vec![config.build.clone()];
-        config.host.extend(extra_host.iter().map(|s| s.to_string()));
-        config.target = config.host.clone();
-        config.target.extend(extra_target.iter().map(|s| s.to_string()));
-
-        let mut build = Build::new(flags, config);
-        let cwd = env::current_dir().unwrap();
-        build.crates.insert("std".to_string(), ::Crate {
-            name: "std".to_string(),
-            deps: Vec::new(),
-            path: cwd.join("src/std"),
-            doc_step: "doc-crate-std".to_string(),
-            build_step: "build-crate-std".to_string(),
-            test_step: "test-crate-std".to_string(),
-            bench_step: "bench-crate-std".to_string(),
-            version: String::new(),
-        });
-        build.crates.insert("test".to_string(), ::Crate {
-            name: "test".to_string(),
-            deps: Vec::new(),
-            path: cwd.join("src/test"),
-            doc_step: "doc-crate-test".to_string(),
-            build_step: "build-crate-test".to_string(),
-            test_step: "test-crate-test".to_string(),
-            bench_step: "bench-crate-test".to_string(),
-            version: String::new(),
-        });
-        build.crates.insert("rustc-main".to_string(), ::Crate {
-            name: "rustc-main".to_string(),
-            deps: Vec::new(),
-            version: String::new(),
-            path: cwd.join("src/rustc-main"),
-            doc_step: "doc-crate-rustc-main".to_string(),
-            build_step: "build-crate-rustc-main".to_string(),
-            test_step: "test-crate-rustc-main".to_string(),
-            bench_step: "bench-crate-rustc-main".to_string(),
-        });
-        return build
-    }
-
-    #[test]
-    fn dist_baseline() {
-        let build = build(&["dist"], &[], &[]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-        assert!(plan.iter().all(|s| s.host == "A" ));
-        assert!(plan.iter().all(|s| s.target == "A" ));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        assert!(plan.contains(&step.name("dist-docs")));
-        assert!(plan.contains(&step.name("dist-mingw")));
-        assert!(plan.contains(&step.name("dist-rustc")));
-        assert!(plan.contains(&step.name("dist-std")));
-        assert!(plan.contains(&step.name("dist-src")));
-    }
-
-    #[test]
-    fn dist_with_targets() {
-        let build = build(&["dist"], &[], &["B"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-        assert!(plan.iter().all(|s| s.host == "A" ));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        assert!(plan.contains(&step.name("dist-docs")));
-        assert!(plan.contains(&step.name("dist-mingw")));
-        assert!(plan.contains(&step.name("dist-rustc")));
-        assert!(plan.contains(&step.name("dist-std")));
-        assert!(plan.contains(&step.name("dist-src")));
-
-        assert!(plan.contains(&step.target("B").name("dist-docs")));
-        assert!(plan.contains(&step.target("B").name("dist-mingw")));
-        assert!(!plan.contains(&step.target("B").name("dist-rustc")));
-        assert!(plan.contains(&step.target("B").name("dist-std")));
-        assert!(!plan.contains(&step.target("B").name("dist-src")));
-    }
-
-    #[test]
-    fn dist_with_hosts() {
-        let build = build(&["dist"], &["B"], &[]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        assert!(!plan.iter().any(|s| s.host == "B"));
-
-        assert!(plan.contains(&step.name("dist-docs")));
-        assert!(plan.contains(&step.name("dist-mingw")));
-        assert!(plan.contains(&step.name("dist-rustc")));
-        assert!(plan.contains(&step.name("dist-std")));
-        assert!(plan.contains(&step.name("dist-src")));
-
-        assert!(plan.contains(&step.target("B").name("dist-docs")));
-        assert!(plan.contains(&step.target("B").name("dist-mingw")));
-        assert!(plan.contains(&step.target("B").name("dist-rustc")));
-        assert!(plan.contains(&step.target("B").name("dist-std")));
-        assert!(!plan.contains(&step.target("B").name("dist-src")));
-    }
-
-    #[test]
-    fn dist_with_targets_and_hosts() {
-        let build = build(&["dist"], &["B"], &["C"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        assert!(!plan.iter().any(|s| s.host == "B"));
-        assert!(!plan.iter().any(|s| s.host == "C"));
-
-        assert!(plan.contains(&step.name("dist-docs")));
-        assert!(plan.contains(&step.name("dist-mingw")));
-        assert!(plan.contains(&step.name("dist-rustc")));
-        assert!(plan.contains(&step.name("dist-std")));
-        assert!(plan.contains(&step.name("dist-src")));
-
-        assert!(plan.contains(&step.target("B").name("dist-docs")));
-        assert!(plan.contains(&step.target("B").name("dist-mingw")));
-        assert!(plan.contains(&step.target("B").name("dist-rustc")));
-        assert!(plan.contains(&step.target("B").name("dist-std")));
-        assert!(!plan.contains(&step.target("B").name("dist-src")));
-
-        assert!(plan.contains(&step.target("C").name("dist-docs")));
-        assert!(plan.contains(&step.target("C").name("dist-mingw")));
-        assert!(!plan.contains(&step.target("C").name("dist-rustc")));
-        assert!(plan.contains(&step.target("C").name("dist-std")));
-        assert!(!plan.contains(&step.target("C").name("dist-src")));
-    }
-
-    #[test]
-    fn dist_target_with_target_flag() {
-        let build = build(&["dist", "--target=C"], &["B"], &["C"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        assert!(!plan.iter().any(|s| s.target == "A"));
-        assert!(!plan.iter().any(|s| s.target == "B"));
-        assert!(!plan.iter().any(|s| s.host == "B"));
-        assert!(!plan.iter().any(|s| s.host == "C"));
-
-        assert!(plan.contains(&step.target("C").name("dist-docs")));
-        assert!(plan.contains(&step.target("C").name("dist-mingw")));
-        assert!(!plan.contains(&step.target("C").name("dist-rustc")));
-        assert!(plan.contains(&step.target("C").name("dist-std")));
-        assert!(!plan.contains(&step.target("C").name("dist-src")));
-    }
-
-    #[test]
-    fn dist_host_with_target_flag() {
-        let build = build(&["dist", "--host=B", "--target=B"], &["B"], &["C"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        assert!(!plan.iter().any(|s| s.target == "A"));
-        assert!(!plan.iter().any(|s| s.target == "C"));
-        assert!(!plan.iter().any(|s| s.host == "B"));
-        assert!(!plan.iter().any(|s| s.host == "C"));
-
-        assert!(plan.contains(&step.target("B").name("dist-docs")));
-        assert!(plan.contains(&step.target("B").name("dist-mingw")));
-        assert!(plan.contains(&step.target("B").name("dist-rustc")));
-        assert!(plan.contains(&step.target("B").name("dist-std")));
-        assert!(plan.contains(&step.target("B").name("dist-src")));
-
-        let all = rules.expand(&plan);
-        println!("all rules: {:#?}", all);
-        assert!(!all.contains(&step.name("rustc")));
-        assert!(!all.contains(&step.name("build-crate-test").stage(1)));
-
-        // all stage0 compiles should be for the build target, A
-        for step in all.iter().filter(|s| s.stage == 0) {
-            if !step.name.contains("build-crate") {
-                continue
-            }
-            println!("step: {:?}", step);
-            assert!(step.host != "B");
-            assert!(step.target != "B");
-            assert!(step.host != "C");
-            assert!(step.target != "C");
-        }
-    }
-
-    #[test]
-    fn build_default() {
-        let build = build(&["build"], &["B"], &["C"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-
-        let step = super::Step {
-            name: "",
-            stage: 2,
-            host: &build.build,
-            target: &build.build,
-        };
-
-        // rustc built for all for of (A, B) x (A, B)
-        assert!(plan.contains(&step.name("librustc")));
-        assert!(plan.contains(&step.target("B").name("librustc")));
-        assert!(plan.contains(&step.host("B").target("A").name("librustc")));
-        assert!(plan.contains(&step.host("B").target("B").name("librustc")));
-
-        // rustc never built for C
-        assert!(!plan.iter().any(|s| {
-            s.name.contains("rustc") && (s.host == "C" || s.target == "C")
-        }));
-
-        // test built for everything
-        assert!(plan.contains(&step.name("libtest")));
-        assert!(plan.contains(&step.target("B").name("libtest")));
-        assert!(plan.contains(&step.host("B").target("A").name("libtest")));
-        assert!(plan.contains(&step.host("B").target("B").name("libtest")));
-        assert!(plan.contains(&step.host("A").target("C").name("libtest")));
-        assert!(plan.contains(&step.host("B").target("C").name("libtest")));
-
-        let all = rules.expand(&plan);
-        println!("all rules: {:#?}", all);
-        assert!(all.contains(&step.name("rustc")));
-        assert!(all.contains(&step.name("libstd")));
-    }
-
-    #[test]
-    fn build_filtered() {
-        let build = build(&["build", "--target=C"], &["B"], &["C"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-
-        assert!(!plan.iter().any(|s| s.name.contains("rustc")));
-        assert!(plan.iter().all(|s| {
-            !s.name.contains("test") || s.target == "C"
-        }));
-    }
-
-    #[test]
-    fn test_default() {
-        let build = build(&["test"], &[], &[]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-        assert!(plan.iter().all(|s| s.host == "A"));
-        assert!(plan.iter().all(|s| s.target == "A"));
-
-        assert!(plan.iter().any(|s| s.name.contains("-ui")));
-        assert!(plan.iter().any(|s| s.name.contains("cfail")));
-        assert!(plan.iter().any(|s| s.name.contains("cfail-full")));
-        assert!(plan.iter().any(|s| s.name.contains("codegen-units")));
-        assert!(plan.iter().any(|s| s.name.contains("debuginfo")));
-        assert!(plan.iter().any(|s| s.name.contains("docs")));
-        assert!(plan.iter().any(|s| s.name.contains("error-index")));
-        assert!(plan.iter().any(|s| s.name.contains("incremental")));
-        assert!(plan.iter().any(|s| s.name.contains("linkchecker")));
-        assert!(plan.iter().any(|s| s.name.contains("mir-opt")));
-        assert!(plan.iter().any(|s| s.name.contains("pfail")));
-        assert!(plan.iter().any(|s| s.name.contains("rfail")));
-        assert!(plan.iter().any(|s| s.name.contains("rfail-full")));
-        assert!(plan.iter().any(|s| s.name.contains("rmake")));
-        assert!(plan.iter().any(|s| s.name.contains("rpass")));
-        assert!(plan.iter().any(|s| s.name.contains("rpass-full")));
-        assert!(plan.iter().any(|s| s.name.contains("rustc-all")));
-        assert!(plan.iter().any(|s| s.name.contains("rustdoc")));
-        assert!(plan.iter().any(|s| s.name.contains("std-all")));
-        assert!(plan.iter().any(|s| s.name.contains("test-all")));
-        assert!(plan.iter().any(|s| s.name.contains("tidy")));
-        assert!(plan.iter().any(|s| s.name.contains("valgrind")));
-    }
-
-    #[test]
-    fn test_with_a_target() {
-        let build = build(&["test", "--target=C"], &[], &["C"]);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(plan.iter().all(|s| s.stage == 2));
-        assert!(plan.iter().all(|s| s.host == "A"));
-        assert!(plan.iter().all(|s| s.target == "C"));
-
-        assert!(plan.iter().any(|s| s.name.contains("-ui")));
-        assert!(!plan.iter().any(|s| s.name.contains("ui-full")));
-        assert!(plan.iter().any(|s| s.name.contains("cfail")));
-        assert!(!plan.iter().any(|s| s.name.contains("cfail-full")));
-        assert!(plan.iter().any(|s| s.name.contains("codegen-units")));
-        assert!(plan.iter().any(|s| s.name.contains("debuginfo")));
-        assert!(!plan.iter().any(|s| s.name.contains("docs")));
-        assert!(!plan.iter().any(|s| s.name.contains("error-index")));
-        assert!(plan.iter().any(|s| s.name.contains("incremental")));
-        assert!(!plan.iter().any(|s| s.name.contains("linkchecker")));
-        assert!(plan.iter().any(|s| s.name.contains("mir-opt")));
-        assert!(plan.iter().any(|s| s.name.contains("pfail")));
-        assert!(plan.iter().any(|s| s.name.contains("rfail")));
-        assert!(!plan.iter().any(|s| s.name.contains("rfail-full")));
-        assert!(!plan.iter().any(|s| s.name.contains("rmake")));
-        assert!(plan.iter().any(|s| s.name.contains("rpass")));
-        assert!(!plan.iter().any(|s| s.name.contains("rpass-full")));
-        assert!(!plan.iter().any(|s| s.name.contains("rustc-all")));
-        assert!(!plan.iter().any(|s| s.name.contains("rustdoc")));
-        assert!(plan.iter().any(|s| s.name.contains("std-all")));
-        assert!(plan.iter().any(|s| s.name.contains("test-all")));
-        assert!(!plan.iter().any(|s| s.name.contains("tidy")));
-        assert!(plan.iter().any(|s| s.name.contains("valgrind")));
-    }
-
-    #[test]
-    fn test_disable_docs() {
-        let build = build_(&["test"], &[], &[], false);
-        let rules = super::build_rules(&build);
-        let plan = rules.plan();
-        println!("rules: {:#?}", plan);
-        assert!(!plan.iter().any(|s| {
-            s.name.contains("doc-") || s.name.contains("default:doc")
-        }));
-        // none of the dependencies should be a doc rule either
-        assert!(!plan.iter().any(|s| {
-            rules.rules[s.name].deps.iter().any(|dep| {
-                let dep = dep(&rules.sbuild.name(s.name));
-                dep.name.contains("doc-") || dep.name.contains("default:doc")
-            })
-        }));
-    }
-}