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
::{Package, PackageId, PackageSet, Target, Workspace}
;
26 use crate::ops
::resolve_all_features
;
27 use crate::util
::interning
::InternedString
;
28 use crate::util
::Config
;
29 use crate::CargoResult
;
31 use std
::collections
::{HashMap, HashSet}
;
33 /// Collection of stuff used while creating the `UnitGraph`.
34 struct State
<'a
, 'cfg
> {
35 ws
: &'a Workspace
<'cfg
>,
37 unit_dependencies
: UnitGraph
,
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
: &'a UnitInterner
,
52 pub fn build_unit_dependencies
<'a
, 'cfg
>(
53 ws
: &'a Workspace
<'cfg
>,
54 package_set
: &'a PackageSet
<'cfg
>,
56 features
: &'a ResolvedFeatures
,
57 std_resolve
: Option
<&'
a (Resolve
, ResolvedFeatures
)>,
59 std_roots
: &HashMap
<CompileKind
, Vec
<Unit
>>,
60 global_mode
: CompileMode
,
61 target_data
: &'a RustcTargetData
,
62 profiles
: &'a Profiles
,
63 interner
: &'a UnitInterner
,
64 ) -> CargoResult
<UnitGraph
> {
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.
111 mut state
: &mut State
<'_
, '_
>,
112 std_roots
: &HashMap
<CompileKind
, Vec
<Unit
>>,
113 ) -> CargoResult
<Option
<UnitGraph
>> {
114 if std_roots
.is_empty() {
117 // Compute dependencies for the standard library.
119 for roots
in std_roots
.values() {
120 deps_of_roots(roots
, &mut state
)?
;
122 state
.is_std
= false;
123 Ok(Some(std
::mem
::take(&mut state
.unit_dependencies
)))
126 /// Add the standard library units to the `unit_dependencies`.
128 state
: &mut State
<'_
, '_
>,
129 std_roots
: &HashMap
<CompileKind
, Vec
<Unit
>>,
130 std_unit_deps
: UnitGraph
,
132 // Attach the standard library as a dependency of every target unit.
133 for (unit
, deps
) in state
.unit_dependencies
.iter_mut() {
134 if !unit
.kind
.is_host() && !unit
.mode
.is_run_custom_build() {
135 deps
.extend(std_roots
[&unit
.kind
].iter().map(|unit
| UnitDep
{
137 unit_for
: UnitFor
::new_normal(),
138 extern_crate_name
: unit
.pkg
.name(),
139 // TODO: Does this `public` make sense?
145 // And also include the dependencies of the standard library itself.
146 for (unit
, deps
) in std_unit_deps
.into_iter() {
147 if let Some(other_unit
) = state
.unit_dependencies
.insert(unit
, deps
) {
148 panic
!("std unit collision with existing unit: {:?}", other_unit
);
153 /// Compute all the dependencies of the given root units.
154 /// The result is stored in state.unit_dependencies.
155 fn deps_of_roots(roots
: &[Unit
], mut state
: &mut State
<'_
, '_
>) -> CargoResult
<()> {
156 for unit
in roots
.iter() {
157 // Dependencies of tests/benches should not have `panic` set.
158 // We check the global test mode to see if we are running in `cargo
159 // test` in which case we ensure all dependencies have `panic`
160 // cleared, and avoid building the lib thrice (once with `panic`, once
161 // without, once for `--test`). In particular, the lib included for
162 // Doc tests and examples are `Build` mode here.
163 let unit_for
= if unit
.mode
.is_any_test() || state
.global_mode
.is_rustc_test() {
164 UnitFor
::new_test(state
.config
)
165 } else if unit
.target
.is_custom_build() {
166 // This normally doesn't happen, except `clean` aggressively
167 // generates all units.
168 UnitFor
::new_host(false)
169 } else if unit
.target
.proc_macro() {
170 UnitFor
::new_host(true)
171 } else if unit
.target
.for_host() {
172 // Plugin should never have panic set.
173 UnitFor
::new_compiler()
175 UnitFor
::new_normal()
177 deps_of(unit
, &mut state
, unit_for
)?
;
183 /// Compute the dependencies of a single unit.
184 fn deps_of(unit
: &Unit
, state
: &mut State
<'_
, '_
>, unit_for
: UnitFor
) -> CargoResult
<()> {
185 // Currently the `unit_dependencies` map does not include `unit_for`. This should
186 // be safe for now. `TestDependency` only exists to clear the `panic`
187 // flag, and you'll never ask for a `unit` with `panic` set as a
188 // `TestDependency`. `CustomBuild` should also be fine since if the
189 // requested unit's settings are the same as `Any`, `CustomBuild` can't
190 // affect anything else in the hierarchy.
191 if !state
.unit_dependencies
.contains_key(unit
) {
192 let unit_deps
= compute_deps(unit
, state
, unit_for
)?
;
195 .insert(unit
.clone(), unit_deps
.clone());
196 for unit_dep
in unit_deps
{
197 deps_of(&unit_dep
.unit
, state
, unit_dep
.unit_for
)?
;
203 /// For a package, returns all targets that are registered as dependencies
204 /// for that package.
205 /// This returns a `Vec` of `(Unit, UnitFor)` pairs. The `UnitFor`
206 /// is the profile type that should be used for dependencies of the unit.
209 state
: &mut State
<'_
, '_
>,
211 ) -> CargoResult
<Vec
<UnitDep
>> {
212 if unit
.mode
.is_run_custom_build() {
213 return compute_deps_custom_build(unit
, unit_for
, state
);
214 } else if unit
.mode
.is_doc() {
215 // Note: this does not include doc test.
216 return compute_deps_doc(unit
, state
);
219 let id
= unit
.pkg
.package_id();
220 let filtered_deps
= state
.resolve().deps(id
).filter(|&(_id
, deps
)| {
221 assert
!(!deps
.is_empty());
222 deps
.iter().any(|dep
| {
223 // If this target is a build command, then we only want build
224 // dependencies, otherwise we want everything *other than* build
226 if unit
.target
.is_custom_build() != dep
.is_build() {
230 // If this dependency is **not** a transitive dependency, then it
231 // only applies to test/example targets.
232 if !dep
.is_transitive()
233 && !unit
.target
.is_test()
234 && !unit
.target
.is_example()
235 && !unit
.mode
.is_any_test()
240 // If this dependency is only available for certain platforms,
241 // make sure we're only enabling it for that platform.
242 if !state
.target_data
.dep_platform_activated(dep
, unit
.kind
) {
246 // If this is an optional dependency, and the new feature resolver
247 // did not enable it, don't include it.
248 if dep
.is_optional() {
249 let features_for
= unit_for
.map_to_features_for();
251 let feats
= state
.activated_features(id
, features_for
);
252 if !feats
.contains(&dep
.name_in_toml()) {
257 // If we've gotten past all that, then this dependency is
262 // Separate line to avoid rustfmt indentation. Must collect due to `state` capture.
263 let filtered_deps
: Vec
<_
> = filtered_deps
.collect();
265 let mut ret
= Vec
::new();
266 for (id
, _
) in filtered_deps
{
267 let pkg
= state
.get(id
);
268 let lib
= match pkg
.targets().iter().find(|t
| t
.is_lib()) {
272 let mode
= check_or_build_mode(unit
.mode
, lib
);
273 let dep_unit_for
= unit_for
274 .with_for_host(lib
.for_host())
275 // If it is a custom build script, then it *only* has build dependencies.
276 .with_host_features(unit
.target
.is_custom_build() || lib
.proc_macro());
278 if state
.config
.cli_unstable().dual_proc_macros
&& lib
.proc_macro() && !unit
.kind
.is_host()
280 let unit_dep
= new_unit_dep(state
, unit
, pkg
, lib
, dep_unit_for
, unit
.kind
, mode
)?
;
283 new_unit_dep(state
, unit
, pkg
, lib
, dep_unit_for
, CompileKind
::Host
, mode
)?
;
286 let unit_dep
= new_unit_dep(
292 unit
.kind
.for_target(lib
),
299 // If this target is a build script, then what we've collected so far is
300 // all we need. If this isn't a build script, then it depends on the
301 // build script if there is one.
302 if unit
.target
.is_custom_build() {
305 ret
.extend(dep_build_script(unit
, unit_for
, state
)?
);
307 // If this target is a binary, test, example, etc, then it depends on
308 // the library of the same package. The call to `resolve.deps` above
309 // didn't include `pkg` in the return values, so we need to special case
310 // it here and see if we need to push `(pkg, pkg_lib_target)`.
311 if unit
.target
.is_lib() && unit
.mode
!= CompileMode
::Doctest
{
314 ret
.extend(maybe_lib(unit
, state
, unit_for
)?
);
316 // If any integration tests/benches are being run, make sure that
317 // binaries are built as well.
318 if !unit
.mode
.is_check()
319 && unit
.mode
.is_any_test()
320 && (unit
.target
.is_test() || unit
.target
.is_bench())
327 // Skip binaries with required features that have not been selected.
328 match t
.required_features() {
329 Some(rf
) if t
.is_bin() => {
330 let features
= resolve_all_features(
336 rf
.iter().all(|f
| features
.contains(f
))
338 None
if t
.is_bin() => true,
348 UnitFor
::new_normal(),
349 unit
.kind
.for_target(t
),
353 .collect
::<CargoResult
<Vec
<UnitDep
>>>()?
,
360 /// Returns the dependencies needed to run a build script.
362 /// The `unit` provided must represent an execution of a build script, and
363 /// the returned set of units must all be run before `unit` is run.
364 fn compute_deps_custom_build(
367 state
: &mut State
<'_
, '_
>,
368 ) -> CargoResult
<Vec
<UnitDep
>> {
369 if let Some(links
) = unit
.pkg
.manifest().links() {
372 .script_override(links
, unit
.kind
)
375 // Overridden build scripts don't have any dependencies.
376 return Ok(Vec
::new());
379 // All dependencies of this unit should use profiles for custom builds.
380 // If this is a build script of a proc macro, make sure it uses host
382 let script_unit_for
= UnitFor
::new_host(unit_for
.is_for_host_features());
383 // When not overridden, then the dependencies to run a build script are:
385 // 1. Compiling the build script itself.
386 // 2. For each immediate dependency of our package which has a `links`
387 // key, the execution of that build script.
389 // We don't have a great way of handling (2) here right now so this is
390 // deferred until after the graph of all unit dependencies has been
392 let unit_dep
= new_unit_dep(
398 // Build scripts always compiled for the host.
405 /// Returns the dependencies necessary to document a package.
406 fn compute_deps_doc(unit
: &Unit
, state
: &mut State
<'_
, '_
>) -> CargoResult
<Vec
<UnitDep
>> {
407 let target_data
= state
.target_data
;
410 .deps(unit
.pkg
.package_id())
411 .filter(|&(_id
, deps
)| {
412 deps
.iter().any(|dep
| match dep
.kind() {
413 DepKind
::Normal
=> target_data
.dep_platform_activated(dep
, unit
.kind
),
418 // To document a library, we depend on dependencies actually being
419 // built. If we're documenting *all* libraries, then we also depend on
420 // the documentation of the library being built.
421 let mut ret
= Vec
::new();
422 for (id
, _deps
) in deps
{
423 let dep
= state
.get(id
);
424 let lib
= match dep
.targets().iter().find(|t
| t
.is_lib()) {
428 // Rustdoc only needs rmeta files for regular dependencies.
429 // However, for plugins/proc macros, deps should be built like normal.
430 let mode
= check_or_build_mode(unit
.mode
, lib
);
431 let dep_unit_for
= UnitFor
::new_normal()
432 .with_for_host(lib
.for_host())
433 .with_host_features(lib
.proc_macro());
434 let lib_unit_dep
= new_unit_dep(
440 unit
.kind
.for_target(lib
),
443 ret
.push(lib_unit_dep
);
444 if let CompileMode
::Doc { deps: true }
= unit
.mode
{
445 // Document this lib as well.
446 let doc_unit_dep
= new_unit_dep(
452 unit
.kind
.for_target(lib
),
455 ret
.push(doc_unit_dep
);
459 // Be sure to build/run the build script for documented libraries.
460 ret
.extend(dep_build_script(unit
, UnitFor
::new_normal(), state
)?
);
462 // If we document a binary/example, we need the library available.
463 if unit
.target
.is_bin() || unit
.target
.is_example() {
464 ret
.extend(maybe_lib(unit
, state
, UnitFor
::new_normal())?
);
471 state
: &mut State
<'_
, '_
>,
473 ) -> CargoResult
<Option
<UnitDep
>> {
477 .find(|t
| t
.is_linkable())
479 let mode
= check_or_build_mode(unit
.mode
, t
);
486 unit
.kind
.for_target(t
),
493 /// If a build script is scheduled to be run for the package specified by
494 /// `unit`, this function will return the unit to run that build script.
496 /// Overriding a build script simply means that the running of the build
497 /// script itself doesn't have any dependencies, so even in that case a unit
498 /// of work is still returned. `None` is only returned if the package has no
503 state
: &State
<'_
, '_
>,
504 ) -> CargoResult
<Option
<UnitDep
>> {
508 .find(|t
| t
.is_custom_build())
510 // The profile stored in the Unit is the profile for the thing
511 // the custom build script is running for.
512 let profile
= state
.profiles
.get_profile_run_custom_build(&unit
.profile
);
513 // UnitFor::new_host is used because we want the `host` flag set
514 // for all of our build dependencies (so they all get
515 // build-override profiles), including compiling the build.rs
518 // If `is_for_host_features` here is `false`, that means we are a
519 // build.rs script for a normal dependency and we want to set the
520 // CARGO_FEATURE_* environment variables to the features as a
523 // If `is_for_host_features` here is `true`, that means that this
524 // package is being used as a build dependency or proc-macro, and
525 // so we only want to set CARGO_FEATURE_* variables for the host
526 // side of the graph.
528 // Keep in mind that the RunCustomBuild unit and the Compile
529 // build.rs unit use the same features. This is because some
530 // people use `cfg!` and `#[cfg]` expressions to check for enabled
531 // features instead of just checking `CARGO_FEATURE_*` at runtime.
532 // In the case with `-Zfeatures=host_dep`, and a shared
533 // dependency has different features enabled for normal vs. build,
534 // then the build.rs script will get compiled twice. I believe it
535 // is not feasible to only build it once because it would break a
536 // large number of scripts (they would think they have the wrong
537 // set of features enabled).
538 let script_unit_for
= UnitFor
::new_host(unit_for
.is_for_host_features());
539 new_unit_dep_with_profile(
546 CompileMode
::RunCustomBuild
,
553 /// Choose the correct mode for dependencies.
554 fn check_or_build_mode(mode
: CompileMode
, target
: &Target
) -> CompileMode
{
556 CompileMode
::Check { .. }
| CompileMode
::Doc { .. }
=> {
557 if target
.for_host() {
558 // Plugin and proc macro targets should be compiled like
562 // Regular dependencies should not be checked with --test.
563 // Regular dependencies of doc targets should emit rmeta only.
564 CompileMode
::Check { test: false }
567 _
=> CompileMode
::Build
,
571 /// Create a new Unit for a dependency from `parent` to `pkg` and `target`.
573 state
: &State
<'_
, '_
>,
580 ) -> CargoResult
<UnitDep
> {
581 let is_local
= pkg
.package_id().source_id().is_path() && !state
.is_std
;
582 let profile
= state
.profiles
.get_profile(
584 state
.ws
.is_member(pkg
),
589 new_unit_dep_with_profile(state
, parent
, pkg
, target
, unit_for
, kind
, mode
, profile
)
592 fn new_unit_dep_with_profile(
593 state
: &State
<'_
, '_
>,
601 ) -> CargoResult
<UnitDep
> {
602 // TODO: consider making extern_crate_name return InternedString?
603 let extern_crate_name
= InternedString
::new(&state
.resolve().extern_crate_name(
604 parent
.pkg
.package_id(),
610 .is_public_dep(parent
.pkg
.package_id(), pkg
.package_id());
611 let features_for
= unit_for
.map_to_features_for();
612 let features
= state
.activated_features(pkg
.package_id(), features_for
);
615 .intern(pkg
, target
, profile
, kind
, mode
, features
, state
.is_std
);
625 /// Fill in missing dependencies for units of the `RunCustomBuild`
627 /// As mentioned above in `compute_deps_custom_build` each build script
628 /// execution has two dependencies. The first is compiling the build script
629 /// itself (already added) and the second is that all crates the package of the
630 /// build script depends on with `links` keys, their build script execution. (a
631 /// bit confusing eh?)
633 /// Here we take the entire `deps` map and add more dependencies from execution
634 /// of one build script to execution of another build script.
635 fn connect_run_custom_build_deps(unit_dependencies
: &mut UnitGraph
) {
636 let mut new_deps
= Vec
::new();
639 // First up build a reverse dependency map. This is a mapping of all
640 // `RunCustomBuild` known steps to the unit which depends on them. For
641 // example a library might depend on a build script, so this map will
642 // have the build script as the key and the library would be in the
644 let mut reverse_deps_map
= HashMap
::new();
645 for (unit
, deps
) in unit_dependencies
.iter() {
647 if dep
.unit
.mode
== CompileMode
::RunCustomBuild
{
649 .entry(dep
.unit
.clone())
650 .or_insert_with(HashSet
::new
)
656 // Next, we take a look at all build scripts executions listed in the
657 // dependency map. Our job here is to take everything that depends on
658 // this build script (from our reverse map above) and look at the other
659 // package dependencies of these parents.
661 // If we depend on a linkable target and the build script mentions
662 // `links`, then we depend on that package's build script! Here we use
663 // `dep_build_script` to manufacture an appropriate build script unit to
665 for unit
in unit_dependencies
667 .filter(|k
| k
.mode
== CompileMode
::RunCustomBuild
)
669 // This is the lib that runs this custom build.
670 let reverse_deps
= match reverse_deps_map
.get(unit
) {
675 let to_add
= reverse_deps
677 // Get all deps for lib.
678 .flat_map(|reverse_dep
| unit_dependencies
[reverse_dep
].iter())
679 // Only deps with `links`.
681 other
.unit
.pkg
!= unit
.pkg
682 && other
.unit
.target
.is_linkable()
683 && other
.unit
.pkg
.manifest().links().is_some()
685 // Get the RunCustomBuild for other lib.
686 .filter_map(|other
| {
687 unit_dependencies
[&other
.unit
]
689 .find(|other_dep
| other_dep
.unit
.mode
== CompileMode
::RunCustomBuild
)
692 .collect
::<HashSet
<_
>>();
694 if !to_add
.is_empty() {
695 // (RunCustomBuild, set(other RunCustomBuild))
696 new_deps
.push((unit
.clone(), to_add
));
701 // And finally, add in all the missing dependencies!
702 for (unit
, new_deps
) in new_deps
{
703 unit_dependencies
.get_mut(&unit
).unwrap().extend(new_deps
);
707 impl<'a
, 'cfg
> State
<'a
, 'cfg
> {
708 fn resolve(&self) -> &'a Resolve
{
710 self.std_resolve
.unwrap()
716 fn features(&self) -> &'a ResolvedFeatures
{
718 self.std_features
.unwrap()
724 fn activated_features(
727 features_for
: FeaturesFor
,
728 ) -> Vec
<InternedString
> {
729 let features
= self.features();
730 features
.activated_features(pkg_id
, features_for
)
733 fn get(&self, id
: PackageId
) -> &'a Package
{
736 .unwrap_or_else(|_
| panic
!("expected {} to be downloaded", id
))