1 //! Constructs the dependency graph for compilation.
3 //! Rust code is typically organized as a set of Cargo packages. The
4 //! dependencies between the packages themselves are stored in the
5 //! `Resolve` struct. However, we can't use that information as is for
6 //! compilation! A package typically contains several targets, or crates,
7 //! and these targets has inter-dependencies. For example, you need to
8 //! compile the `lib` target before the `bin` one, and you need to compile
9 //! `build.rs` before either of those.
11 //! So, we need to lower the `Resolve`, which specifies dependencies between
12 //! *packages*, to a graph of dependencies between their *targets*, and this
13 //! is exactly what this module is doing! Well, almost exactly: another
14 //! complication is that we might want to compile the same target several times
15 //! (for example, with and without tests), so we actually build a dependency
16 //! graph of `Unit`s, which capture these properties.
18 use crate::core
::compiler
::unit_graph
::{UnitDep, UnitGraph}
;
19 use crate::core
::compiler
::UnitInterner
;
20 use crate::core
::compiler
::{CompileKind, CompileMode, RustcTargetData, Unit}
;
21 use crate::core
::dependency
::DepKind
;
22 use crate::core
::profiles
::{Profile, Profiles, UnitFor}
;
23 use crate::core
::resolver
::features
::{FeaturesFor, ResolvedFeatures}
;
24 use crate::core
::resolver
::Resolve
;
25 use crate::core
::{InternedString, Package, PackageId, PackageSet, Target, Workspace}
;
26 use crate::ops
::resolve_all_features
;
27 use crate::util
::Config
;
28 use crate::CargoResult
;
30 use std
::collections
::{HashMap, HashSet}
;
33 /// Collection of stuff used while creating the `UnitGraph`.
34 struct State
<'a
, 'unit
, 'cfg
> {
35 ws
: &'a Workspace
<'cfg
>,
37 unit_dependencies
: UnitGraph
<'unit
>,
38 package_set
: &'a PackageSet
<'cfg
>,
39 usr_resolve
: &'a Resolve
,
40 usr_features
: &'a ResolvedFeatures
,
41 std_resolve
: Option
<&'a Resolve
>,
42 std_features
: Option
<&'a ResolvedFeatures
>,
43 /// This flag is `true` while generating the dependencies for the standard
46 global_mode
: CompileMode
,
47 target_data
: &'a RustcTargetData
,
48 profiles
: &'a Profiles
,
49 interner
: &'unit UnitInterner
,
52 pub fn build_unit_dependencies
<'a
, 'unit
, 'cfg
>(
53 ws
: &'a Workspace
<'cfg
>,
54 package_set
: &'a PackageSet
<'cfg
>,
56 features
: &'a ResolvedFeatures
,
57 std_resolve
: Option
<&'
a (Resolve
, ResolvedFeatures
)>,
58 roots
: &[Unit
<'unit
>],
59 std_roots
: &[Unit
<'unit
>],
60 global_mode
: CompileMode
,
61 target_data
: &'a RustcTargetData
,
62 profiles
: &'a Profiles
,
63 interner
: &'unit UnitInterner
,
64 ) -> CargoResult
<UnitGraph
<'unit
>> {
65 let (std_resolve
, std_features
) = match std_resolve
{
66 Some((r
, f
)) => (Some(r
), Some(f
)),
69 let mut state
= State
{
72 unit_dependencies
: HashMap
::new(),
75 usr_features
: features
,
85 let std_unit_deps
= calc_deps_of_std(&mut state
, std_roots
)?
;
87 deps_of_roots(roots
, &mut state
)?
;
88 super::links
::validate_links(state
.resolve(), &state
.unit_dependencies
)?
;
89 // Hopefully there aren't any links conflicts with the standard library?
91 if let Some(std_unit_deps
) = std_unit_deps
{
92 attach_std_deps(&mut state
, std_roots
, std_unit_deps
);
95 connect_run_custom_build_deps(&mut state
.unit_dependencies
);
97 // Dependencies are used in tons of places throughout the backend, many of
98 // which affect the determinism of the build itself. As a result be sure
99 // that dependency lists are always sorted to ensure we've always got a
100 // deterministic output.
101 for list
in state
.unit_dependencies
.values_mut() {
104 trace
!("ALL UNIT DEPENDENCIES {:#?}", state
.unit_dependencies
);
106 Ok(state
.unit_dependencies
)
109 /// Compute all the dependencies for the standard library.
110 fn calc_deps_of_std
<'unit
>(
111 mut state
: &mut State
<'_
, 'unit
, '_
>,
112 std_roots
: &[Unit
<'unit
>],
113 ) -> CargoResult
<Option
<UnitGraph
<'unit
>>> {
114 if std_roots
.is_empty() {
117 // Compute dependencies for the standard library.
119 deps_of_roots(std_roots
, &mut state
)?
;
120 state
.is_std
= false;
121 Ok(Some(std
::mem
::replace(
122 &mut state
.unit_dependencies
,
127 /// Add the standard library units to the `unit_dependencies`.
128 fn attach_std_deps
<'unit
>(
129 state
: &mut State
<'_
, 'unit
, '_
>,
130 std_roots
: &[Unit
<'unit
>],
131 std_unit_deps
: UnitGraph
<'unit
>,
133 // Attach the standard library as a dependency of every target unit.
134 for (unit
, deps
) in state
.unit_dependencies
.iter_mut() {
135 if !unit
.kind
.is_host() && !unit
.mode
.is_run_custom_build() {
136 deps
.extend(std_roots
.iter().map(|unit
| UnitDep
{
138 unit_for
: UnitFor
::new_normal(),
139 extern_crate_name
: unit
.pkg
.name(),
140 // TODO: Does this `public` make sense?
146 // And also include the dependencies of the standard library itself.
147 for (unit
, deps
) in std_unit_deps
.into_iter() {
148 if let Some(other_unit
) = state
.unit_dependencies
.insert(unit
, deps
) {
149 panic
!("std unit collision with existing unit: {:?}", other_unit
);
154 /// Compute all the dependencies of the given root units.
155 /// The result is stored in state.unit_dependencies.
156 fn deps_of_roots
<'unit
>(
157 roots
: &[Unit
<'unit
>],
158 mut state
: &mut State
<'_
, 'unit
, '_
>,
159 ) -> CargoResult
<()> {
160 for unit
in roots
.iter() {
161 // Dependencies of tests/benches should not have `panic` set.
162 // We check the global test mode to see if we are running in `cargo
163 // test` in which case we ensure all dependencies have `panic`
164 // cleared, and avoid building the lib thrice (once with `panic`, once
165 // without, once for `--test`). In particular, the lib included for
166 // Doc tests and examples are `Build` mode here.
167 let unit_for
= if unit
.mode
.is_any_test() || state
.global_mode
.is_rustc_test() {
168 UnitFor
::new_test(state
.config
)
169 } else if unit
.target
.is_custom_build() {
170 // This normally doesn't happen, except `clean` aggressively
171 // generates all units.
172 UnitFor
::new_host(false)
173 } else if unit
.target
.proc_macro() {
174 UnitFor
::new_host(true)
175 } else if unit
.target
.for_host() {
176 // Plugin should never have panic set.
177 UnitFor
::new_compiler()
179 UnitFor
::new_normal()
181 deps_of(unit
, &mut state
, unit_for
)?
;
187 /// Compute the dependencies of a single unit.
190 state
: &mut State
<'_
, 'unit
, '_
>,
192 ) -> CargoResult
<()> {
193 // Currently the `unit_dependencies` map does not include `unit_for`. This should
194 // be safe for now. `TestDependency` only exists to clear the `panic`
195 // flag, and you'll never ask for a `unit` with `panic` set as a
196 // `TestDependency`. `CustomBuild` should also be fine since if the
197 // requested unit's settings are the same as `Any`, `CustomBuild` can't
198 // affect anything else in the hierarchy.
199 if !state
.unit_dependencies
.contains_key(unit
) {
200 let unit_deps
= compute_deps(unit
, state
, unit_for
)?
;
201 state
.unit_dependencies
.insert(*unit
, unit_deps
.clone());
202 for unit_dep
in unit_deps
{
203 deps_of(&unit_dep
.unit
, state
, unit_dep
.unit_for
)?
;
209 /// For a package, returns all targets that are registered as dependencies
210 /// for that package.
211 /// This returns a `Vec` of `(Unit, UnitFor)` pairs. The `UnitFor`
212 /// is the profile type that should be used for dependencies of the unit.
213 fn compute_deps
<'unit
>(
215 state
: &mut State
<'_
, 'unit
, '_
>,
217 ) -> CargoResult
<Vec
<UnitDep
<'unit
>>> {
218 if unit
.mode
.is_run_custom_build() {
219 return compute_deps_custom_build(unit
, unit_for
, state
);
220 } else if unit
.mode
.is_doc() {
221 // Note: this does not include doc test.
222 return compute_deps_doc(unit
, state
);
225 let id
= unit
.pkg
.package_id();
226 let filtered_deps
= state
.resolve().deps(id
).filter(|&(_id
, deps
)| {
227 assert
!(!deps
.is_empty());
228 deps
.iter().any(|dep
| {
229 // If this target is a build command, then we only want build
230 // dependencies, otherwise we want everything *other than* build
232 if unit
.target
.is_custom_build() != dep
.is_build() {
236 // If this dependency is **not** a transitive dependency, then it
237 // only applies to test/example targets.
238 if !dep
.is_transitive()
239 && !unit
.target
.is_test()
240 && !unit
.target
.is_example()
241 && !unit
.mode
.is_any_test()
246 // If this dependency is only available for certain platforms,
247 // make sure we're only enabling it for that platform.
248 if !state
.target_data
.dep_platform_activated(dep
, unit
.kind
) {
252 // If this is an optional dependency, and the new feature resolver
253 // did not enable it, don't include it.
254 if dep
.is_optional() {
255 let features_for
= unit_for
.map_to_features_for();
257 let feats
= state
.activated_features(id
, features_for
);
258 if !feats
.contains(&dep
.name_in_toml()) {
263 // If we've gotten past all that, then this dependency is
268 // Separate line to avoid rustfmt indentation. Must collect due to `state` capture.
269 let filtered_deps
: Vec
<_
> = filtered_deps
.collect();
271 let mut ret
= Vec
::new();
272 for (id
, _
) in filtered_deps
{
273 let pkg
= state
.get(id
);
274 let lib
= match pkg
.targets().iter().find(|t
| t
.is_lib()) {
278 let mode
= check_or_build_mode(unit
.mode
, lib
);
279 let dep_unit_for
= unit_for
280 .with_for_host(lib
.for_host())
281 // If it is a custom build script, then it *only* has build dependencies.
282 .with_host_features(unit
.target
.is_custom_build() || lib
.proc_macro());
284 if state
.config
.cli_unstable().dual_proc_macros
&& lib
.proc_macro() && !unit
.kind
.is_host()
286 let unit_dep
= new_unit_dep(state
, unit
, pkg
, lib
, dep_unit_for
, unit
.kind
, mode
)?
;
289 new_unit_dep(state
, unit
, pkg
, lib
, dep_unit_for
, CompileKind
::Host
, mode
)?
;
292 let unit_dep
= new_unit_dep(
298 unit
.kind
.for_target(lib
),
305 // If this target is a build script, then what we've collected so far is
306 // all we need. If this isn't a build script, then it depends on the
307 // build script if there is one.
308 if unit
.target
.is_custom_build() {
311 ret
.extend(dep_build_script(unit
, unit_for
, state
)?
);
313 // If this target is a binary, test, example, etc, then it depends on
314 // the library of the same package. The call to `resolve.deps` above
315 // didn't include `pkg` in the return values, so we need to special case
316 // it here and see if we need to push `(pkg, pkg_lib_target)`.
317 if unit
.target
.is_lib() && unit
.mode
!= CompileMode
::Doctest
{
320 ret
.extend(maybe_lib(unit
, state
, unit_for
)?
);
322 // If any integration tests/benches are being run, make sure that
323 // binaries are built as well.
324 if !unit
.mode
.is_check()
325 && unit
.mode
.is_any_test()
326 && (unit
.target
.is_test() || unit
.target
.is_bench())
333 // Skip binaries with required features that have not been selected.
334 match t
.required_features() {
335 Some(rf
) if t
.is_bin() => {
336 let features
= resolve_all_features(
342 rf
.iter().all(|f
| features
.contains(f
))
344 None
if t
.is_bin() => true,
354 UnitFor
::new_normal(),
355 unit
.kind
.for_target(t
),
359 .collect
::<CargoResult
<Vec
<UnitDep
<'unit
>>>>()?
,
366 /// Returns the dependencies needed to run a build script.
368 /// The `unit` provided must represent an execution of a build script, and
369 /// the returned set of units must all be run before `unit` is run.
370 fn compute_deps_custom_build
<'unit
>(
373 state
: &mut State
<'_
, 'unit
, '_
>,
374 ) -> CargoResult
<Vec
<UnitDep
<'unit
>>> {
375 if let Some(links
) = unit
.pkg
.manifest().links() {
378 .script_override(links
, unit
.kind
)
381 // Overridden build scripts don't have any dependencies.
382 return Ok(Vec
::new());
385 // All dependencies of this unit should use profiles for custom builds.
386 // If this is a build script of a proc macro, make sure it uses host
388 let script_unit_for
= UnitFor
::new_host(unit_for
.is_for_host_features());
389 // When not overridden, then the dependencies to run a build script are:
391 // 1. Compiling the build script itself.
392 // 2. For each immediate dependency of our package which has a `links`
393 // key, the execution of that build script.
395 // We don't have a great way of handling (2) here right now so this is
396 // deferred until after the graph of all unit dependencies has been
398 let unit_dep
= new_unit_dep(
404 // Build scripts always compiled for the host.
411 /// Returns the dependencies necessary to document a package.
412 fn compute_deps_doc
<'unit
>(
414 state
: &mut State
<'_
, 'unit
, '_
>,
415 ) -> CargoResult
<Vec
<UnitDep
<'unit
>>> {
416 let target_data
= state
.target_data
;
419 .deps(unit
.pkg
.package_id())
420 .filter(|&(_id
, deps
)| {
421 deps
.iter().any(|dep
| match dep
.kind() {
422 DepKind
::Normal
=> target_data
.dep_platform_activated(dep
, unit
.kind
),
427 // To document a library, we depend on dependencies actually being
428 // built. If we're documenting *all* libraries, then we also depend on
429 // the documentation of the library being built.
430 let mut ret
= Vec
::new();
431 for (id
, _deps
) in deps
{
432 let dep
= state
.get(id
);
433 let lib
= match dep
.targets().iter().find(|t
| t
.is_lib()) {
437 // Rustdoc only needs rmeta files for regular dependencies.
438 // However, for plugins/proc macros, deps should be built like normal.
439 let mode
= check_or_build_mode(unit
.mode
, lib
);
440 let dep_unit_for
= UnitFor
::new_normal()
441 .with_for_host(lib
.for_host())
442 .with_host_features(lib
.proc_macro());
443 let lib_unit_dep
= new_unit_dep(
449 unit
.kind
.for_target(lib
),
452 ret
.push(lib_unit_dep
);
453 if let CompileMode
::Doc { deps: true }
= unit
.mode
{
454 // Document this lib as well.
455 let doc_unit_dep
= new_unit_dep(
461 unit
.kind
.for_target(lib
),
464 ret
.push(doc_unit_dep
);
468 // Be sure to build/run the build script for documented libraries.
469 ret
.extend(dep_build_script(unit
, UnitFor
::new_normal(), state
)?
);
471 // If we document a binary/example, we need the library available.
472 if unit
.target
.is_bin() || unit
.target
.is_example() {
473 ret
.extend(maybe_lib(unit
, state
, UnitFor
::new_normal())?
);
480 state
: &mut State
<'_
, 'unit
, '_
>,
482 ) -> CargoResult
<Option
<UnitDep
<'unit
>>> {
486 .find(|t
| t
.linkable())
488 let mode
= check_or_build_mode(unit
.mode
, t
);
495 unit
.kind
.for_target(t
),
502 /// If a build script is scheduled to be run for the package specified by
503 /// `unit`, this function will return the unit to run that build script.
505 /// Overriding a build script simply means that the running of the build
506 /// script itself doesn't have any dependencies, so even in that case a unit
507 /// of work is still returned. `None` is only returned if the package has no
509 fn dep_build_script
<'unit
>(
512 state
: &State
<'_
, 'unit
, '_
>,
513 ) -> CargoResult
<Option
<UnitDep
<'unit
>>> {
517 .find(|t
| t
.is_custom_build())
519 // The profile stored in the Unit is the profile for the thing
520 // the custom build script is running for.
521 let profile
= state
.profiles
.get_profile_run_custom_build(&unit
.profile
);
522 // UnitFor::new_host is used because we want the `host` flag set
523 // for all of our build dependencies (so they all get
524 // build-override profiles), including compiling the build.rs
527 // If `is_for_host_features` here is `false`, that means we are a
528 // build.rs script for a normal dependency and we want to set the
529 // CARGO_FEATURE_* environment variables to the features as a
532 // If `is_for_host_features` here is `true`, that means that this
533 // package is being used as a build dependency or proc-macro, and
534 // so we only want to set CARGO_FEATURE_* variables for the host
535 // side of the graph.
537 // Keep in mind that the RunCustomBuild unit and the Compile
538 // build.rs unit use the same features. This is because some
539 // people use `cfg!` and `#[cfg]` expressions to check for enabled
540 // features instead of just checking `CARGO_FEATURE_*` at runtime.
541 // In the case with `-Zfeatures=host_dep`, and a shared
542 // dependency has different features enabled for normal vs. build,
543 // then the build.rs script will get compiled twice. I believe it
544 // is not feasible to only build it once because it would break a
545 // large number of scripts (they would think they have the wrong
546 // set of features enabled).
547 let script_unit_for
= UnitFor
::new_host(unit_for
.is_for_host_features());
548 new_unit_dep_with_profile(
555 CompileMode
::RunCustomBuild
,
562 /// Choose the correct mode for dependencies.
563 fn check_or_build_mode(mode
: CompileMode
, target
: &Target
) -> CompileMode
{
565 CompileMode
::Check { .. }
| CompileMode
::Doc { .. }
=> {
566 if target
.for_host() {
567 // Plugin and proc macro targets should be compiled like
571 // Regular dependencies should not be checked with --test.
572 // Regular dependencies of doc targets should emit rmeta only.
573 CompileMode
::Check { test: false }
576 _
=> CompileMode
::Build
,
580 /// Create a new Unit for a dependency from `parent` to `pkg` and `target`.
581 fn new_unit_dep
<'unit
>(
582 state
: &State
<'_
, 'unit
, '_
>,
583 parent
: &Unit
<'unit
>,
589 ) -> CargoResult
<UnitDep
<'unit
>> {
593 .get_profile(pkg
.package_id(), state
.ws
.is_member(pkg
), unit_for
, mode
);
594 new_unit_dep_with_profile(state
, parent
, pkg
, target
, unit_for
, kind
, mode
, profile
)
597 fn new_unit_dep_with_profile
<'unit
>(
598 state
: &State
<'_
, 'unit
, '_
>,
599 parent
: &Unit
<'unit
>,
606 ) -> CargoResult
<UnitDep
<'unit
>> {
607 // TODO: consider making extern_crate_name return InternedString?
608 let extern_crate_name
= InternedString
::new(&state
.resolve().extern_crate_name(
609 parent
.pkg
.package_id(),
615 .is_public_dep(parent
.pkg
.package_id(), pkg
.package_id());
616 let features_for
= unit_for
.map_to_features_for();
617 let features
= state
.activated_features(pkg
.package_id(), features_for
);
620 .intern(pkg
, target
, profile
, kind
, mode
, features
, state
.is_std
);
630 /// Fill in missing dependencies for units of the `RunCustomBuild`
632 /// As mentioned above in `compute_deps_custom_build` each build script
633 /// execution has two dependencies. The first is compiling the build script
634 /// itself (already added) and the second is that all crates the package of the
635 /// build script depends on with `links` keys, their build script execution. (a
636 /// bit confusing eh?)
638 /// Here we take the entire `deps` map and add more dependencies from execution
639 /// of one build script to execution of another build script.
640 fn connect_run_custom_build_deps(unit_dependencies
: &mut UnitGraph
<'_
>) {
641 let mut new_deps
= Vec
::new();
644 // First up build a reverse dependency map. This is a mapping of all
645 // `RunCustomBuild` known steps to the unit which depends on them. For
646 // example a library might depend on a build script, so this map will
647 // have the build script as the key and the library would be in the
649 let mut reverse_deps_map
= HashMap
::new();
650 for (unit
, deps
) in unit_dependencies
.iter() {
652 if dep
.unit
.mode
== CompileMode
::RunCustomBuild
{
655 .or_insert_with(HashSet
::new
)
661 // Next, we take a look at all build scripts executions listed in the
662 // dependency map. Our job here is to take everything that depends on
663 // this build script (from our reverse map above) and look at the other
664 // package dependencies of these parents.
666 // If we depend on a linkable target and the build script mentions
667 // `links`, then we depend on that package's build script! Here we use
668 // `dep_build_script` to manufacture an appropriate build script unit to
670 for unit
in unit_dependencies
672 .filter(|k
| k
.mode
== CompileMode
::RunCustomBuild
)
674 // This is the lib that runs this custom build.
675 let reverse_deps
= match reverse_deps_map
.get(unit
) {
680 let to_add
= reverse_deps
682 // Get all deps for lib.
683 .flat_map(|reverse_dep
| unit_dependencies
[reverse_dep
].iter())
684 // Only deps with `links`.
686 other
.unit
.pkg
!= unit
.pkg
687 && other
.unit
.target
.linkable()
688 && other
.unit
.pkg
.manifest().links().is_some()
690 // Get the RunCustomBuild for other lib.
691 .filter_map(|other
| {
692 unit_dependencies
[&other
.unit
]
694 .find(|other_dep
| other_dep
.unit
.mode
== CompileMode
::RunCustomBuild
)
697 .collect
::<HashSet
<_
>>();
699 if !to_add
.is_empty() {
700 // (RunCustomBuild, set(other RunCustomBuild))
701 new_deps
.push((*unit
, to_add
));
706 // And finally, add in all the missing dependencies!
707 for (unit
, new_deps
) in new_deps
{
708 unit_dependencies
.get_mut(&unit
).unwrap().extend(new_deps
);
712 impl<'a
, 'unit
, 'cfg
> State
<'a
, 'unit
, 'cfg
> {
713 fn resolve(&self) -> &'a Resolve
{
715 self.std_resolve
.unwrap()
721 fn features(&self) -> &'a ResolvedFeatures
{
723 self.std_features
.unwrap()
729 fn activated_features(
732 features_for
: FeaturesFor
,
733 ) -> Vec
<InternedString
> {
734 let features
= self.features();
735 features
.activated_features(pkg_id
, features_for
)
738 fn get(&self, id
: PackageId
) -> &'a Rc
<Package
> {
741 .unwrap_or_else(|_
| panic
!("expected {} to be downloaded", id
))