#
cargo/ops/cargo_compile/
mod.rs

    1//! The entry point for starting the compilation process for commands like
    2//! `build`, `test`, `doc`, `rustc`, etc.
    3//!
    4//! The [`compile`] function will do all the work to compile a workspace. A
    5//! rough outline is:
    6//!
    7//! 1. Resolve the dependency graph (see [`ops::resolve`]).
    8//! 2. Download any packages needed (see [`PackageSet`]).
    9//! 3. Generate a list of top-level "units" of work for the targets the user
    10//!   requested on the command-line. Each [`Unit`] corresponds to a compiler
    11//!   invocation. This is done in this module ([`UnitGenerator::generate_root_units`]).
    12//! 4. Starting from the root [`Unit`]s, generate the [`UnitGraph`] by walking the dependency graph
    13//!   from the resolver.  See also [`unit_dependencies`].
    14//! 5. Construct the [`BuildContext`] with all of the information collected so
    15//!   far. This is the end of the "front end" of compilation.
    16//! 6. Create a [`BuildRunner`] which coordinates the compilation process
    17//!   and will perform the following steps:
    18//!     1. Prepare the `target` directory (see [`Layout`]).
    19//!     2. Create a [`JobQueue`]. The queue checks the
    20//!       fingerprint of each `Unit` to determine if it should run or be
    21//!       skipped.
    22//!     3. Execute the queue via [`drain_the_queue`]. Each leaf in the queue's dependency graph is
    23//!        executed, and then removed from the graph when finished. This repeats until the queue is
    24//!        empty.  Note that this is the only point in cargo that currently uses threads.
    25//! 7. The result of the compilation is stored in the [`Compilation`] struct. This can be used for
    26//!    various things, such as running tests after the compilation  has finished.
    27//!
    28//! **Note**: "target" inside this module generally refers to ["Cargo Target"],
    29//! which corresponds to artifact that will be built in a package. Not to be
    30//! confused with target-triple or target architecture.
    31//!
    32//! [`unit_dependencies`]: crate::core::compiler::unit_dependencies
    33//! [`Layout`]: crate::core::compiler::Layout
    34//! [`JobQueue`]: crate::core::compiler::job_queue
    35//! [`drain_the_queue`]: crate::core::compiler::job_queue
    36//! ["Cargo Target"]: https://doc.rust-lang.org/nightly/cargo/reference/cargo-targets.html
    37
    38use std::collections::{HashMap, HashSet};
    39use std::hash::{Hash, Hasher};
    40use std::sync::Arc;
    41
    42use crate::core::compiler::UserIntent;
    43use crate::core::compiler::unit_dependencies::build_unit_dependencies;
    44use crate::core::compiler::unit_graph::{self, UnitDep, UnitGraph};
    45use crate::core::compiler::{BuildConfig, BuildContext, BuildRunner, Compilation};
    46use crate::core::compiler::{CompileKind, CompileTarget, RustcTargetData, Unit};
    47use crate::core::compiler::{CrateType, TargetInfo, apply_env_config, standard_lib};
    48use crate::core::compiler::{DefaultExecutor, Executor, UnitInterner};
    49use crate::core::profiles::Profiles;
    50use crate::core::resolver::features::{self, CliFeatures, FeaturesFor};
    51use crate::core::resolver::{HasDevUnits, Resolve};
    52use crate::core::{PackageId, PackageSet, SourceId, TargetKind, Workspace};
    53use crate::drop_println;
    54use crate::ops;
    55use crate::ops::resolve::{SpecsAndResolvedFeatures, WorkspaceResolve};
    56use crate::util::context::{GlobalContext, WarningHandling};
    57use crate::util::interning::InternedString;
    58use crate::util::{CargoResult, StableHasher};
    59
    60mod compile_filter;
    61pub use compile_filter::{CompileFilter, FilterRule, LibRule};
    62
    63pub(super) mod unit_generator;
    64use unit_generator::UnitGenerator;
    65
    66mod packages;
    67
    68pub use packages::Packages;
    69
    70/// Contains information about how a package should be compiled.
    71///
    72/// Note on distinction between `CompileOptions` and [`BuildConfig`]:
    73/// `BuildConfig` contains values that need to be retained after
    74/// [`BuildContext`] is created. The other fields are no longer necessary. Think
    75/// of it as `CompileOptions` are high-level settings requested on the
    76/// command-line, and `BuildConfig` are low-level settings for actually
    77/// driving `rustc`.
    78#[derive(Debug, Clone)]
    79pub struct CompileOptions {
    80    /// Configuration information for a rustc build
    81    pub build_config: BuildConfig,
    82    /// Feature flags requested by the user.
    83    pub cli_features: CliFeatures,
    84    /// A set of packages to build.
    85    pub spec: Packages,
    86    /// Filter to apply to the root package to select which targets will be
    87    /// built.
    88    pub filter: CompileFilter,
    89    /// Extra arguments to be passed to rustdoc (single target only)
    90    pub target_rustdoc_args: Option<Vec<String>>,
    91    /// The specified target will be compiled with all the available arguments,
    92    /// note that this only accounts for the *final* invocation of rustc
    93    pub target_rustc_args: Option<Vec<String>>,
    94    /// Crate types to be passed to rustc (single target only)
    95    pub target_rustc_crate_types: Option<Vec<String>>,
    96    /// Whether the `--document-private-items` flags was specified and should
    97    /// be forwarded to `rustdoc`.
    98    pub rustdoc_document_private_items: bool,
    99    /// Whether the build process should check the minimum Rust version
    100    /// defined in the cargo metadata for a crate.
    101    pub honor_rust_version: Option<bool>,
    102}
    103
    104impl CompileOptions {
    105    pub fn new(gctx: &GlobalContext, intent: UserIntent) -> CargoResult<CompileOptions> {
    106        let jobs = None;
    107        let keep_going = false;
    108        Ok(CompileOptions {
    109            build_config: BuildConfig::new(gctx, jobs, keep_going, &[], intent)?,
    110            cli_features: CliFeatures::new_all(false),
    111            spec: ops::Packages::Packages(Vec::new()),
    112            filter: CompileFilter::Default {
    113                required_features_filterable: false,
    114            },
    115            target_rustdoc_args: None,
    116            target_rustc_args: None,
    117            target_rustc_crate_types: None,
    118            rustdoc_document_private_items: false,
    119            honor_rust_version: None,
    120        })
    121    }
    122}
    123
    124/// Compiles!
    125///
    126/// This uses the [`DefaultExecutor`]. To use a custom [`Executor`], see [`compile_with_exec`].
    127pub fn compile<'a>(ws: &Workspace<'a>, options: &CompileOptions) -> CargoResult<Compilation<'a>> {
    128    let exec: Arc<dyn Executor> = Arc::new(DefaultExecutor);
    129    compile_with_exec(ws, options, &exec)
    130}
    131
    132/// Like [`compile`] but allows specifying a custom [`Executor`]
    133/// that will be able to intercept build calls and add custom logic.
    134///
    135/// [`compile`] uses [`DefaultExecutor`] which just passes calls through.
    136pub fn compile_with_exec<'a>(
    137    ws: &Workspace<'a>,
    138    options: &CompileOptions,
    139    exec: &Arc<dyn Executor>,
    140) -> CargoResult<Compilation<'a>> {
    141    ws.emit_warnings()?;
    142    let compilation = compile_ws(ws, options, exec)?;
    143    if ws.gctx().warning_handling()? == WarningHandling::Deny && compilation.warning_count > 0 {
    144        anyhow::bail!("warnings are denied by `build.warnings` configuration")
    145    }
    146    Ok(compilation)
    147}
    148
    149/// Like [`compile_with_exec`] but without warnings from manifest parsing.
    150#[tracing::instrument(skip_all)]
    151pub fn compile_ws<'a>(
    152    ws: &Workspace<'a>,
    153    options: &CompileOptions,
    154    exec: &Arc<dyn Executor>,
    155) -> CargoResult<Compilation<'a>> {
    156    let interner = UnitInterner::new();
    157    let bcx = create_bcx(ws, options, &interner)?;
    158    if options.build_config.unit_graph {
    159        unit_graph::emit_serialized_unit_graph(&bcx.roots, &bcx.unit_graph, ws.gctx())?;
    160        return Compilation::new(&bcx);
    161    }
    162    crate::core::gc::auto_gc(bcx.gctx);
    163    let build_runner = BuildRunner::new(&bcx)?;
    164    if options.build_config.dry_run {
    165        build_runner.dry_run()
    166    } else {
    167        build_runner.compile(exec)
    168    }
    169}
    170
    171/// Executes `rustc --print <VALUE>`.
    172///
    173/// * `print_opt_value` is the VALUE passed through.
    174pub fn print<'a>(
    175    ws: &Workspace<'a>,
    176    options: &CompileOptions,
    177    print_opt_value: &str,
    178) -> CargoResult<()> {
    179    let CompileOptions {
    180        ref build_config,
    181        ref target_rustc_args,
    182        ..
    183    } = *options;
    184    let gctx = ws.gctx();
    185    let rustc = gctx.load_global_rustc(Some(ws))?;
    186    for (index, kind) in build_config.requested_kinds.iter().enumerate() {
    187        if index != 0 {
    188            drop_println!(gctx);
    189        }
    190        let target_info = TargetInfo::new(gctx, &build_config.requested_kinds, &rustc, *kind)?;
    191        let mut process = rustc.process();
    192        apply_env_config(gctx, &mut process)?;
    193        process.args(&target_info.rustflags);
    194        if let Some(args) = target_rustc_args {
    195            process.args(args);
    196        }
    197        if let CompileKind::Target(t) = kind {
    198            process.arg("--target").arg(t.rustc_target());
    199        }
    200        process.arg("--print").arg(print_opt_value);
    201        process.exec()?;
    202    }
    203    Ok(())
    204}
    205
    206/// Prepares all required information for the actual compilation.
    207///
    208/// For how it works and what data it collects,
    209/// please see the [module-level documentation](self).
    210#[tracing::instrument(skip_all)]
    211pub fn create_bcx<'a, 'gctx>(
    212    ws: &'a Workspace<'gctx>,
    213    options: &'a CompileOptions,
    214    interner: &'a UnitInterner,
    215) -> CargoResult<BuildContext<'a, 'gctx>> {
    216    let CompileOptions {
    217        ref build_config,
    218        ref spec,
    219        ref cli_features,
    220        ref filter,
    221        ref target_rustdoc_args,
    222        ref target_rustc_args,
    223        ref target_rustc_crate_types,
    224        rustdoc_document_private_items,
    225        honor_rust_version,
    226    } = *options;
    227    let gctx = ws.gctx();
    228
    229    // Perform some pre-flight validation.
    230    match build_config.intent {
    231        UserIntent::Test | UserIntent::Build | UserIntent::Check { .. } | UserIntent::Bench => {
    232            if ws.gctx().get_env("RUST_FLAGS").is_ok() {
    233                gctx.shell()
    234                    .warn("ignoring environment variable `RUST_FLAGS`")?;
    235                gctx.shell().note("rust flags are passed via `RUSTFLAGS`")?;
    236            }
    237        }
    238        UserIntent::Doc { .. } | UserIntent::Doctest => {
    239            if ws.gctx().get_env("RUSTDOC_FLAGS").is_ok() {
    240                gctx.shell()
    241                    .warn("ignoring environment variable `RUSTDOC_FLAGS`")?;
    242                gctx.shell()
    243                    .note("rustdoc flags are passed via `RUSTDOCFLAGS`")?;
    244            }
    245        }
    246    }
    247    gctx.validate_term_config()?;
    248
    249    let mut target_data = RustcTargetData::new(ws, &build_config.requested_kinds)?;
    250
    251    let specs = spec.to_package_id_specs(ws)?;
    252    let has_dev_units = {
    253        // Rustdoc itself doesn't need dev-dependencies. But to scrape examples from packages in the
    254        // workspace, if any of those packages need dev-dependencies, then we need include dev-dependencies
    255        // to scrape those packages.
    256        let any_pkg_has_scrape_enabled = ws
    257            .members_with_features(&specs, cli_features)?
    258            .iter()
    259            .any(|(pkg, _)| {
    260                pkg.targets()
    261                    .iter()
    262                    .any(|target| target.is_example() && target.doc_scrape_examples().is_enabled())
    263            });
    264
    265        if filter.need_dev_deps(build_config.intent)
    266            || (build_config.intent.is_doc() && any_pkg_has_scrape_enabled)
    267        {
    268            HasDevUnits::Yes
    269        } else {
    270            HasDevUnits::No
    271        }
    272    };
    273    let dry_run = false;
    274    let resolve = ops::resolve_ws_with_opts(
    275        ws,
    276        &mut target_data,
    277        &build_config.requested_kinds,
    278        cli_features,
    279        &specs,
    280        has_dev_units,
    281        crate::core::resolver::features::ForceAllTargets::No,
    282        dry_run,
    283    )?;
    284    let WorkspaceResolve {
    285        mut pkg_set,
    286        workspace_resolve,
    287        targeted_resolve: resolve,
    288        specs_and_features,
    289    } = resolve;
    290
    291    let std_resolve_features = if let Some(crates) = &gctx.cli_unstable().build_std {
    292        let (std_package_set, std_resolve, std_features) = standard_lib::resolve_std(
    293            ws,
    294            &mut target_data,
    295            &build_config,
    296            crates,
    297            &build_config.requested_kinds,
    298        )?;
    299        pkg_set.add_set(std_package_set);
    300        Some((std_resolve, std_features))
    301    } else {
    302        None
    303    };
    304
    305    // Find the packages in the resolver that the user wants to build (those
    306    // passed in with `-p` or the defaults from the workspace), and convert
    307    // Vec<PackageIdSpec> to a Vec<PackageId>.
    308    let to_build_ids = resolve.specs_to_ids(&specs)?;
    309    // Now get the `Package` for each `PackageId`. This may trigger a download
    310    // if the user specified `-p` for a dependency that is not downloaded.
    311    // Dependencies will be downloaded during build_unit_dependencies.
    312    let mut to_builds = pkg_set.get_many(to_build_ids)?;
    313
    314    // The ordering here affects some error messages coming out of cargo, so
    315    // let's be test and CLI friendly by always printing in the same order if
    316    // there's an error.
    317    to_builds.sort_by_key(|p| p.package_id());
    318
    319    for pkg in to_builds.iter() {
    320        pkg.manifest().print_teapot(gctx);
    321
    322        if build_config.intent.is_any_test()
    323            && !ws.is_member(pkg)
    324            && pkg.dependencies().iter().any(|dep| !dep.is_transitive())
    325        {
    326            anyhow::bail!(
    327                "package `{}` cannot be tested because it requires dev-dependencies \
    328                 and is not a member of the workspace",
    329                pkg.name()
    330            );
    331        }
    332    }
    333
    334    let (extra_args, extra_args_name) = match (target_rustc_args, target_rustdoc_args) {
    335        (Some(args), _) => (Some(args.clone()), "rustc"),
    336        (_, Some(args)) => (Some(args.clone()), "rustdoc"),
    337        _ => (None, ""),
    338    };
    339
    340    if extra_args.is_some() && to_builds.len() != 1 {
    341        panic!(
    342            "`{}` should not accept multiple `-p` flags",
    343            extra_args_name
    344        );
    345    }
    346
    347    let profiles = Profiles::new(ws, build_config.requested_profile)?;
    348    profiles.validate_packages(
    349        ws.profiles(),
    350        &mut gctx.shell(),
    351        workspace_resolve.as_ref().unwrap_or(&resolve),
    352    )?;
    353
    354    // If `--target` has not been specified, then the unit graph is built
    355    // assuming `--target $HOST` was specified. See
    356    // `rebuild_unit_graph_shared` for more on why this is done.
    357    let explicit_host_kind = CompileKind::Target(CompileTarget::new(&target_data.rustc.host)?);
    358    let explicit_host_kinds: Vec<_> = build_config
    359        .requested_kinds
    360        .iter()
    361        .map(|kind| match kind {
    362            CompileKind::Host => explicit_host_kind,
    363            CompileKind::Target(t) => CompileKind::Target(*t),
    364        })
    365        .collect();
    366
    367    let mut units = Vec::new();
    368    let mut unit_graph = HashMap::new();
    369    let mut scrape_units = Vec::new();
    370
    371    for SpecsAndResolvedFeatures {
    372        specs,
    373        resolved_features,
    374    } in &specs_and_features
    375    {
    376        // Passing `build_config.requested_kinds` instead of
    377        // `explicit_host_kinds` here so that `generate_root_units` can do
    378        // its own special handling of `CompileKind::Host`. It will
    379        // internally replace the host kind by the `explicit_host_kind`
    380        // before setting as a unit.
    381        let spec_names = specs.iter().map(|spec| spec.name()).collect::<Vec<_>>();
    382        let packages = to_builds
    383            .iter()
    384            .filter(|package| spec_names.contains(&package.name().as_str()))
    385            .cloned()
    386            .collect::<Vec<_>>();
    387        let generator = UnitGenerator {
    388            ws,
    389            packages: &packages,
    390            spec,
    391            target_data: &target_data,
    392            filter,
    393            requested_kinds: &build_config.requested_kinds,
    394            explicit_host_kind,
    395            intent: build_config.intent,
    396            resolve: &resolve,
    397            workspace_resolve: &workspace_resolve,
    398            resolved_features: &resolved_features,
    399            package_set: &pkg_set,
    400            profiles: &profiles,
    401            interner,
    402            has_dev_units,
    403        };
    404        let mut targeted_root_units = generator.generate_root_units()?;
    405
    406        if let Some(args) = target_rustc_crate_types {
    407            override_rustc_crate_types(&mut targeted_root_units, args, interner)?;
    408        }
    409
    410        let should_scrape =
    411            build_config.intent.is_doc() && gctx.cli_unstable().rustdoc_scrape_examples;
    412        let targeted_scrape_units = if should_scrape {
    413            generator.generate_scrape_units(&targeted_root_units)?
    414        } else {
    415            Vec::new()
    416        };
    417
    418        let std_roots = if let Some(crates) = gctx.cli_unstable().build_std.as_ref() {
    419            let (std_resolve, std_features) = std_resolve_features.as_ref().unwrap();
    420            standard_lib::generate_std_roots(
    421                &crates,
    422                &targeted_root_units,
    423                std_resolve,
    424                std_features,
    425                &explicit_host_kinds,
    426                &pkg_set,
    427                interner,
    428                &profiles,
    429                &target_data,
    430            )?
    431        } else {
    432            Default::default()
    433        };
    434
    435        unit_graph.extend(build_unit_dependencies(
    436            ws,
    437            &pkg_set,
    438            &resolve,
    439            &resolved_features,
    440            std_resolve_features.as_ref(),
    441            &targeted_root_units,
    442            &targeted_scrape_units,
    443            &std_roots,
    444            build_config.intent,
    445            &target_data,
    446            &profiles,
    447            interner,
    448        )?);
    449        units.extend(targeted_root_units);
    450        scrape_units.extend(targeted_scrape_units);
    451    }
    452
    453    // TODO: In theory, Cargo should also dedupe the roots, but I'm uncertain
    454    // what heuristics to use in that case.
    455    if build_config.intent.wants_deps_docs() {
    456        remove_duplicate_doc(build_config, &units, &mut unit_graph);
    457    }
    458
    459    let host_kind_requested = build_config
    460        .requested_kinds
    461        .iter()
    462        .any(CompileKind::is_host);
    463    // Rebuild the unit graph, replacing the explicit host targets with
    464    // CompileKind::Host, removing `artifact_target_for_features` and merging any dependencies
    465    // shared with build and artifact dependencies.
    466    (units, scrape_units, unit_graph) = rebuild_unit_graph_shared(
    467        interner,
    468        unit_graph,
    469        &units,
    470        &scrape_units,
    471        host_kind_requested.then_some(explicit_host_kind),
    472        build_config.compile_time_deps_only,
    473    );
    474
    475    let mut extra_compiler_args = HashMap::new();
    476    if let Some(args) = extra_args {
    477        if units.len() != 1 {
    478            anyhow::bail!(
    479                "extra arguments to `{}` can only be passed to one \
    480                 target, consider filtering\nthe package by passing, \
    481                 e.g., `--lib` or `--bin NAME` to specify a single target",
    482                extra_args_name
    483            );
    484        }
    485        extra_compiler_args.insert(units[0].clone(), args);
    486    }
    487
    488    for unit in units
    489        .iter()
    490        .filter(|unit| unit.mode.is_doc() || unit.mode.is_doc_test())
    491        .filter(|unit| rustdoc_document_private_items || unit.target.is_bin())
    492    {
    493        // Add `--document-private-items` rustdoc flag if requested or if
    494        // the target is a binary. Binary crates get their private items
    495        // documented by default.
    496        let mut args = vec!["--document-private-items".into()];
    497        if unit.target.is_bin() {
    498            // This warning only makes sense if it's possible to document private items
    499            // sometimes and ignore them at other times. But cargo consistently passes
    500            // `--document-private-items`, so the warning isn't useful.
    501            args.push("-Arustdoc::private-intra-doc-links".into());
    502        }
    503        extra_compiler_args
    504            .entry(unit.clone())
    505            .or_default()
    506            .extend(args);
    507    }
    508
    509    if honor_rust_version.unwrap_or(true) {
    510        let rustc_version = target_data.rustc.version.clone().into();
    511
    512        let mut incompatible = Vec::new();
    513        let mut local_incompatible = false;
    514        for unit in unit_graph.keys() {
    515            let Some(pkg_msrv) = unit.pkg.rust_version() else {
    516                continue;
    517            };
    518
    519            if pkg_msrv.is_compatible_with(&rustc_version) {
    520                continue;
    521            }
    522
    523            local_incompatible |= unit.is_local();
    524            incompatible.push((unit, pkg_msrv));
    525        }
    526        if !incompatible.is_empty() {
    527            use std::fmt::Write as _;
    528
    529            let plural = if incompatible.len() == 1 { "" } else { "s" };
    530            let mut message = format!(
    531                "rustc {rustc_version} is not supported by the following package{plural}:\n"
    532            );
    533            incompatible.sort_by_key(|(unit, _)| (unit.pkg.name(), unit.pkg.version()));
    534            for (unit, msrv) in incompatible {
    535                let name = &unit.pkg.name();
    536                let version = &unit.pkg.version();
    537                writeln!(&mut message, "  {name}@{version} requires rustc {msrv}").unwrap();
    538            }
    539            if ws.is_ephemeral() {
    540                if ws.ignore_lock() {
    541                    writeln!(
    542                        &mut message,
    543                        "Try re-running `cargo install` with `--locked`"
    544                    )
    545                    .unwrap();
    546                }
    547            } else if !local_incompatible {
    548                writeln!(
    549                    &mut message,
    550                    "Either upgrade rustc or select compatible dependency versions with
    551`cargo update <name>@<current-ver> --precise <compatible-ver>`
    552where `<compatible-ver>` is the latest version supporting rustc {rustc_version}",
    553                )
    554                .unwrap();
    555            }
    556            return Err(anyhow::Error::msg(message));
    557        }
    558    }
    559
    560    let bcx = BuildContext::new(
    561        ws,
    562        pkg_set,
    563        build_config,
    564        profiles,
    565        extra_compiler_args,
    566        target_data,
    567        units,
    568        unit_graph,
    569        scrape_units,
    570    )?;
    571
    572    Ok(bcx)
    573}
    574
    575/// This is used to rebuild the unit graph, sharing host dependencies if possible,
    576/// and applying other unit adjustments based on the whole graph.
    577///
    578/// This will translate any unit's `CompileKind::Target(host)` to
    579/// `CompileKind::Host` if `to_host` is not `None` and the kind is equal to `to_host`.
    580/// This also handles generating the unit `dep_hash`, and merging shared units if possible.
    581///
    582/// This is necessary because if normal dependencies used `CompileKind::Host`,
    583/// there would be no way to distinguish those units from build-dependency
    584/// units or artifact dependency units.
    585/// This can cause a problem if a shared normal/build/artifact dependency needs
    586/// to link to another dependency whose features differ based on whether or
    587/// not it is a normal, build or artifact dependency. If all units used
    588/// `CompileKind::Host`, then they would end up being identical, causing a
    589/// collision in the `UnitGraph`, and Cargo would end up randomly choosing one
    590/// value or the other.
    591///
    592/// The solution is to keep normal, build and artifact dependencies separate when
    593/// building the unit graph, and then run this second pass which will try to
    594/// combine shared dependencies safely. By adding a hash of the dependencies
    595/// to the `Unit`, this allows the `CompileKind` to be changed back to `Host`
    596/// and `artifact_target_for_features` to be removed without fear of an unwanted
    597/// collision for build or artifact dependencies.
    598///
    599/// This is also responsible for adjusting the `strip` profile option to
    600/// opportunistically strip if debug is 0 for all dependencies. This helps
    601/// remove debuginfo added by the standard library.
    602///
    603/// This is also responsible for adjusting the `debug` setting for host
    604/// dependencies, turning off debug if the user has not explicitly enabled it,
    605/// and the unit is not shared with a target unit.
    606///
    607/// This is also responsible for adjusting whether each unit should be compiled
    608/// or not regarding `--compile-time-deps` flag.
    609fn rebuild_unit_graph_shared(
    610    interner: &UnitInterner,
    611    unit_graph: UnitGraph,
    612    roots: &[Unit],
    613    scrape_units: &[Unit],
    614    to_host: Option<CompileKind>,
    615    compile_time_deps_only: bool,
    616) -> (Vec<Unit>, Vec<Unit>, UnitGraph) {
    617    let mut result = UnitGraph::new();
    618    // Map of the old unit to the new unit, used to avoid recursing into units
    619    // that have already been computed to improve performance.
    620    let mut memo = HashMap::new();
    621    let new_roots = roots
    622        .iter()
    623        .map(|root| {
    624            traverse_and_share(
    625                interner,
    626                &mut memo,
    627                &mut result,
    628                &unit_graph,
    629                root,
    630                true,
    631                false,
    632                to_host,
    633                compile_time_deps_only,
    634            )
    635        })
    636        .collect();
    637    // If no unit in the unit graph ended up having scrape units attached as dependencies,
    638    // then they won't have been discovered in traverse_and_share and hence won't be in
    639    // memo. So we filter out missing scrape units.
    640    let new_scrape_units = scrape_units
    641        .iter()
    642        .map(|unit| memo.get(unit).unwrap().clone())
    643        .collect();
    644    (new_roots, new_scrape_units, result)
    645}
    646
    647/// Recursive function for rebuilding the graph.
    648///
    649/// This walks `unit_graph`, starting at the given `unit`. It inserts the new
    650/// units into `new_graph`, and returns a new updated version of the given
    651/// unit (`dep_hash` is filled in, and `kind` switched if necessary).
    652fn traverse_and_share(
    653    interner: &UnitInterner,
    654    memo: &mut HashMap<Unit, Unit>,
    655    new_graph: &mut UnitGraph,
    656    unit_graph: &UnitGraph,
    657    unit: &Unit,
    658    unit_is_root: bool,
    659    unit_is_for_host: bool,
    660    to_host: Option<CompileKind>,
    661    compile_time_deps_only: bool,
    662) -> Unit {
    663    if let Some(new_unit) = memo.get(unit) {
    664        // Already computed, no need to recompute.
    665        return new_unit.clone();
    666    }
    667    let mut dep_hash = StableHasher::new();
    668    let skip_non_compile_time_deps = compile_time_deps_only
    669        && (!unit.target.is_compile_time_dependency() ||
    670            // Root unit is not a dependency unless other units are dependant
    671            // to it.
    672            unit_is_root);
    673    let new_deps: Vec<_> = unit_graph[unit]
    674        .iter()
    675        .map(|dep| {
    676            let new_dep_unit = traverse_and_share(
    677                interner,
    678                memo,
    679                new_graph,
    680                unit_graph,
    681                &dep.unit,
    682                false,
    683                dep.unit_for.is_for_host(),
    684                to_host,
    685                // If we should compile the current unit, we should also compile
    686                // its dependencies. And if not, we should compile compile time
    687                // dependencies only.
    688                skip_non_compile_time_deps,
    689            );
    690            new_dep_unit.hash(&mut dep_hash);
    691            UnitDep {
    692                unit: new_dep_unit,
    693                ..dep.clone()
    694            }
    695        })
    696        .collect();
    697    // Here, we have recursively traversed this unit's dependencies, and hashed them: we can
    698    // finalize the dep hash.
    699    let new_dep_hash = Hasher::finish(&dep_hash);
    700
    701    // This is the key part of the sharing process: if the unit is a runtime dependency, whose
    702    // target is the same as the host, we canonicalize the compile kind to `CompileKind::Host`.
    703    // A possible host dependency counterpart to this unit would have that kind, and if such a unit
    704    // exists in the current `unit_graph`, they will unify in the new unit graph map `new_graph`.
    705    // The resulting unit graph will be optimized with less units, thanks to sharing these host
    706    // dependencies.
    707    let canonical_kind = match to_host {
    708        Some(to_host) if to_host == unit.kind => CompileKind::Host,
    709        _ => unit.kind,
    710    };
    711
    712    let mut profile = unit.profile.clone();
    713    if profile.strip.is_deferred() {
    714        // If strip was not manually set, and all dependencies of this unit together
    715        // with this unit have debuginfo turned off, we enable debuginfo stripping.
    716        // This will remove pre-existing debug symbols coming from the standard library.
    717        if !profile.debuginfo.is_turned_on()
    718            && new_deps
    719                .iter()
    720                .all(|dep| !dep.unit.profile.debuginfo.is_turned_on())
    721        {
    722            profile.strip = profile.strip.strip_debuginfo();
    723        }
    724    }
    725
    726    // If this is a build dependency, and it's not shared with runtime dependencies, we can weaken
    727    // its debuginfo level to optimize build times. We do nothing if it's an artifact dependency,
    728    // as it and its debuginfo may end up embedded in the main program.
    729    if unit_is_for_host
    730        && to_host.is_some()
    731        && profile.debuginfo.is_deferred()
    732        && !unit.artifact.is_true()
    733    {
    734        // We create a "probe" test to see if a unit with the same explicit debuginfo level exists
    735        // in the graph. This is the level we'd expect if it was set manually or the default value
    736        // set by a profile for a runtime dependency: its canonical value.
    737        let canonical_debuginfo = profile.debuginfo.finalize();
    738        let mut canonical_profile = profile.clone();
    739        canonical_profile.debuginfo = canonical_debuginfo;
    740        let unit_probe = interner.intern(
    741            &unit.pkg,
    742            &unit.target,
    743            canonical_profile,
    744            to_host.unwrap(),
    745            unit.mode,
    746            unit.features.clone(),
    747            unit.rustflags.clone(),
    748            unit.rustdocflags.clone(),
    749            unit.links_overrides.clone(),
    750            unit.is_std,
    751            unit.dep_hash,
    752            unit.artifact,
    753            unit.artifact_target_for_features,
    754            unit.skip_non_compile_time_dep,
    755        );
    756
    757        // We can now turn the deferred value into its actual final value.
    758        profile.debuginfo = if unit_graph.contains_key(&unit_probe) {
    759            // The unit is present in both build time and runtime subgraphs: we canonicalize its
    760            // level to the other unit's, thus ensuring reuse between the two to optimize build times.
    761            canonical_debuginfo
    762        } else {
    763            // The unit is only present in the build time subgraph, we can weaken its debuginfo
    764            // level to optimize build times.
    765            canonical_debuginfo.weaken()
    766        }
    767    }
    768
    769    let new_unit = interner.intern(
    770        &unit.pkg,
    771        &unit.target,
    772        profile,
    773        canonical_kind,
    774        unit.mode,
    775        unit.features.clone(),
    776        unit.rustflags.clone(),
    777        unit.rustdocflags.clone(),
    778        unit.links_overrides.clone(),
    779        unit.is_std,
    780        new_dep_hash,
    781        unit.artifact,
    782        // Since `dep_hash` is now filled in, there's no need to specify the artifact target
    783        // for target-dependent feature resolution
    784        None,
    785        skip_non_compile_time_deps,
    786    );
    787    if !unit_is_root || !compile_time_deps_only {
    788        assert!(memo.insert(unit.clone(), new_unit.clone()).is_none());
    789    }
    790    new_graph.entry(new_unit.clone()).or_insert(new_deps);
    791    new_unit
    792}
    793
    794/// Removes duplicate `CompileMode::Doc` units that would cause problems with
    795/// filename collisions.
    796///
    797/// Rustdoc only separates units by crate name in the file directory
    798/// structure. If any two units with the same crate name exist, this would
    799/// cause a filename collision, causing different rustdoc invocations to stomp
    800/// on one another's files.
    801///
    802/// Unfortunately this does not remove all duplicates, as some of them are
    803/// either user error, or difficult to remove. Cases that I can think of:
    804///
    805/// - Same target name in different packages. See the `collision_doc` test.
    806/// - Different sources. See `collision_doc_sources` test.
    807///
    808/// Ideally this would not be necessary.
    809fn remove_duplicate_doc(
    810    build_config: &BuildConfig,
    811    root_units: &[Unit],
    812    unit_graph: &mut UnitGraph,
    813) {
    814    // First, create a mapping of crate_name -> Unit so we can see where the
    815    // duplicates are.
    816    let mut all_docs: HashMap<String, Vec<Unit>> = HashMap::new();
    817    for unit in unit_graph.keys() {
    818        if unit.mode.is_doc() {
    819            all_docs
    820                .entry(unit.target.crate_name())
    821                .or_default()
    822                .push(unit.clone());
    823        }
    824    }
    825    // Keep track of units to remove so that they can be efficiently removed
    826    // from the unit_deps.
    827    let mut removed_units: HashSet<Unit> = HashSet::new();
    828    let mut remove = |units: Vec<Unit>, reason: &str, cb: &dyn Fn(&Unit) -> bool| -> Vec<Unit> {
    829        let (to_remove, remaining_units): (Vec<Unit>, Vec<Unit>) = units
    830            .into_iter()
    831            .partition(|unit| cb(unit) && !root_units.contains(unit));
    832        for unit in to_remove {
    833            tracing::debug!(
    834                "removing duplicate doc due to {} for package {} target `{}`",
    835                reason,
    836                unit.pkg,
    837                unit.target.name()
    838            );
    839            unit_graph.remove(&unit);
    840            removed_units.insert(unit);
    841        }
    842        remaining_units
    843    };
    844    // Iterate over the duplicates and try to remove them from unit_graph.
    845    for (_crate_name, mut units) in all_docs {
    846        if units.len() == 1 {
    847            continue;
    848        }
    849        // Prefer target over host if --target was not specified.
    850        if build_config
    851            .requested_kinds
    852            .iter()
    853            .all(CompileKind::is_host)
    854        {
    855            // Note these duplicates may not be real duplicates, since they
    856            // might get merged in rebuild_unit_graph_shared. Either way, it
    857            // shouldn't hurt to remove them early (although the report in the
    858            // log might be confusing).
    859            units = remove(units, "host/target merger", &|unit| unit.kind.is_host());
    860            if units.len() == 1 {
    861                continue;
    862            }
    863        }
    864        // Prefer newer versions over older.
    865        let mut source_map: HashMap<(InternedString, SourceId, CompileKind), Vec<Unit>> =
    866            HashMap::new();
    867        for unit in units {
    868            let pkg_id = unit.pkg.package_id();
    869            // Note, this does not detect duplicates from different sources.
    870            source_map
    871                .entry((pkg_id.name(), pkg_id.source_id(), unit.kind))
    872                .or_default()
    873                .push(unit);
    874        }
    875        let mut remaining_units = Vec::new();
    876        for (_key, mut units) in source_map {
    877            if units.len() > 1 {
    878                units.sort_by(|a, b| a.pkg.version().partial_cmp(b.pkg.version()).unwrap());
    879                // Remove any entries with version < newest.
    880                let newest_version = units.last().unwrap().pkg.version().clone();
    881                let keep_units = remove(units, "older version", &|unit| {
    882                    unit.pkg.version() < &newest_version
    883                });
    884                remaining_units.extend(keep_units);
    885            } else {
    886                remaining_units.extend(units);
    887            }
    888        }
    889        if remaining_units.len() == 1 {
    890            continue;
    891        }
    892        // Are there other heuristics to remove duplicates that would make
    893        // sense? Maybe prefer path sources over all others?
    894    }
    895    // Also remove units from the unit_deps so there aren't any dangling edges.
    896    for unit_deps in unit_graph.values_mut() {
    897        unit_deps.retain(|unit_dep| !removed_units.contains(&unit_dep.unit));
    898    }
    899    // Remove any orphan units that were detached from the graph.
    900    let mut visited = HashSet::new();
    901    fn visit(unit: &Unit, graph: &UnitGraph, visited: &mut HashSet<Unit>) {
    902        if !visited.insert(unit.clone()) {
    903            return;
    904        }
    905        for dep in &graph[unit] {
    906            visit(&dep.unit, graph, visited);
    907        }
    908    }
    909    for unit in root_units {
    910        visit(unit, unit_graph, &mut visited);
    911    }
    912    unit_graph.retain(|unit, _| visited.contains(unit));
    913}
    914
    915/// Override crate types for given units.
    916///
    917/// This is primarily used by `cargo rustc --crate-type`.
    918fn override_rustc_crate_types(
    919    units: &mut [Unit],
    920    args: &[String],
    921    interner: &UnitInterner,
    922) -> CargoResult<()> {
    923    if units.len() != 1 {
    924        anyhow::bail!(
    925            "crate types to rustc can only be passed to one \
    926            target, consider filtering\nthe package by passing, \
    927            e.g., `--lib` or `--example` to specify a single target"
    928        );
    929    }
    930
    931    let unit = &units[0];
    932    let override_unit = |f: fn(Vec<CrateType>) -> TargetKind| {
    933        let crate_types = args.iter().map(|s| s.into()).collect();
    934        let mut target = unit.target.clone();
    935        target.set_kind(f(crate_types));
    936        interner.intern(
    937            &unit.pkg,
    938            &target,
    939            unit.profile.clone(),
    940            unit.kind,
    941            unit.mode,
    942            unit.features.clone(),
    943            unit.rustflags.clone(),
    944            unit.rustdocflags.clone(),
    945            unit.links_overrides.clone(),
    946            unit.is_std,
    947            unit.dep_hash,
    948            unit.artifact,
    949            unit.artifact_target_for_features,
    950            unit.skip_non_compile_time_dep,
    951        )
    952    };
    953    units[0] = match unit.target.kind() {
    954        TargetKind::Lib(_) => override_unit(TargetKind::Lib),
    955        TargetKind::ExampleLib(_) => override_unit(TargetKind::ExampleLib),
    956        _ => {
    957            anyhow::bail!(
    958                "crate types can only be specified for libraries and example libraries.\n\
    959                Binaries, tests, and benchmarks are always the `bin` crate type"
    960            );
    961        }
    962    };
    963
    964    Ok(())
    965}
    966
    967/// Gets all of the features enabled for a package, plus its dependencies'
    968/// features.
    969///
    970/// Dependencies are added as `dep_name/feat_name` because `required-features`
    971/// wants to support that syntax.
    972pub fn resolve_all_features(
    973    resolve_with_overrides: &Resolve,
    974    resolved_features: &features::ResolvedFeatures,
    975    package_set: &PackageSet<'_>,
    976    package_id: PackageId,
    977) -> HashSet<String> {
    978    let mut features: HashSet<String> = resolved_features
    979        .activated_features(package_id, FeaturesFor::NormalOrDev)
    980        .iter()
    981        .map(|s| s.to_string())
    982        .collect();
    983
    984    // Include features enabled for use by dependencies so targets can also use them with the
    985    // required-features field when deciding whether to be built or skipped.
    986    for (dep_id, deps) in resolve_with_overrides.deps(package_id) {
    987        let is_proc_macro = package_set
    988            .get_one(dep_id)
    989            .expect("packages downloaded")
    990            .proc_macro();
    991        for dep in deps {
    992            let features_for = FeaturesFor::from_for_host(is_proc_macro || dep.is_build());
    993            for feature in resolved_features
    994                .activated_features_unverified(dep_id, features_for)
    995                .unwrap_or_default()
    996            {
    997                features.insert(format!("{}/{}", dep.name_in_toml(), feature));
    998            }
    999        }
    1000    }
    1001
    1002    features
    1003}