#
cargo/ops/
resolve.rs

    1//! High-level APIs for executing the resolver.
    2//!
    3//! This module provides functions for running the resolver given a workspace, including loading
    4//! the `Cargo.lock` file and checking if it needs updating.
    5//!
    6//! There are roughly 3 main functions:
    7//!
    8//! - [`resolve_ws`]: A simple, high-level function with no options.
    9//! - [`resolve_ws_with_opts`]: A medium-level function with options like
    10//!   user-provided features. This is the most appropriate function to use in
    11//!   most cases.
    12//! - [`resolve_with_previous`]: A low-level function for running the resolver,
    13//!   providing the most power and flexibility.
    14//!
    15//! ### Data Structures
    16//!
    17//! - [`Workspace`]:
    18//!   Usually created by [`crate::util::command_prelude::ArgMatchesExt::workspace`] which discovers the root of the
    19//!   workspace, and loads all the workspace members as a [`Package`] object
    20//!   - [`Package`]
    21//!     Corresponds with `Cargo.toml` manifest (deserialized as [`Manifest`]) and its associated files.
    22//!     - [`Target`]s are crates such as the library, binaries, integration test, or examples.
    23//!       They are what is actually compiled by `rustc`.
    24//!       Each `Target` defines a crate root, like `src/lib.rs` or `examples/foo.rs`.
    25//!     - [`PackageId`] --- A unique identifier for a package.
    26//! - [`PackageRegistry`]:
    27//!   The primary interface for how the dependency
    28//!   resolver finds packages. It contains the `SourceMap`, and handles things
    29//!   like the `[patch]` table. The dependency resolver
    30//!   sends a query to the `PackageRegistry` to "get me all packages that match
    31//!   this dependency declaration". The `Registry` trait provides a generic interface
    32//!   to the `PackageRegistry`, but this is only used for providing an alternate
    33//!   implementation of the `PackageRegistry` for testing.
    34//! - [`SourceMap`]: Map of all available sources.
    35//!   - [`Source`]: An abstraction for something that can fetch packages (a remote
    36//!     registry, a git repo, the local filesystem, etc.). Check out the [source
    37//!     implementations] for all the details about registries, indexes, git
    38//!     dependencies, etc.
    39//!       * [`SourceId`]: A unique identifier for a source.
    40//!   - [`Summary`]: A of a [`Manifest`], and is essentially
    41//!     the information that can be found in a registry index. Queries against the
    42//!     `PackageRegistry` yields a `Summary`. The resolver uses the summary
    43//!     information to build the dependency graph.
    44//! - [`PackageSet`] --- Contains all the `Package` objects. This works with the
    45//!   [`Downloads`] struct to coordinate downloading packages. It has a reference
    46//!   to the `SourceMap` to get the `Source` objects which tell the `Downloads`
    47//!   struct which URLs to fetch.
    48//!
    49//! [`Package`]: crate::core::package
    50//! [`Target`]: crate::core::Target
    51//! [`Manifest`]: crate::core::Manifest
    52//! [`Source`]: crate::sources::source::Source
    53//! [`SourceMap`]: crate::sources::source::SourceMap
    54//! [`PackageRegistry`]: crate::core::registry::PackageRegistry
    55//! [source implementations]: crate::sources
    56//! [`Downloads`]: crate::core::package::Downloads
    57
    58use crate::core::Dependency;
    59use crate::core::GitReference;
    60use crate::core::PackageId;
    61use crate::core::PackageIdSpec;
    62use crate::core::PackageIdSpecQuery;
    63use crate::core::PackageSet;
    64use crate::core::SourceId;
    65use crate::core::Workspace;
    66use crate::core::compiler::{CompileKind, RustcTargetData};
    67use crate::core::registry::{LockedPatchDependency, PackageRegistry};
    68use crate::core::resolver::features::{
    69    CliFeatures, FeatureOpts, FeatureResolver, ForceAllTargets, RequestedFeatures, ResolvedFeatures,
    70};
    71use crate::core::resolver::{
    72    self, HasDevUnits, Resolve, ResolveOpts, ResolveVersion, VersionOrdering, VersionPreferences,
    73};
    74use crate::core::summary::Summary;
    75use crate::ops;
    76use crate::sources::RecursivePathSource;
    77use crate::util::CanonicalUrl;
    78use crate::util::cache_lock::CacheLockMode;
    79use crate::util::context::FeatureUnification;
    80use crate::util::errors::CargoResult;
    81use annotate_snippets::Group;
    82use annotate_snippets::Level;
    83use anyhow::Context as _;
    84use cargo_util::paths;
    85use cargo_util_schemas::core::PartialVersion;
    86use std::borrow::Cow;
    87use std::collections::{HashMap, HashSet};
    88use std::rc::Rc;
    89use tracing::{debug, trace};
    90
    91/// Filter for keep using Package ID from previous lockfile.
    92type Keep<'a> = &'a dyn Fn(&PackageId) -> bool;
    93
    94/// Result for `resolve_ws_with_opts`.
    95pub struct WorkspaceResolve<'gctx> {
    96    /// Packages to be downloaded.
    97    pub pkg_set: PackageSet<'gctx>,
    98    /// The resolve for the entire workspace.
    99    ///
    100    /// This may be `None` for things like `cargo install` and `-Zavoid-dev-deps`.
    101    /// This does not include `paths` overrides.
    102    pub workspace_resolve: Option<Resolve>,
    103    /// The narrowed resolve, with the specific features enabled.
    104    pub targeted_resolve: Resolve,
    105    /// Package specs requested for compilation along with specific features enabled. This usually
    106    /// has the length of one but there may be more specs with different features when using the
    107    /// `package` feature resolver.
    108    pub specs_and_features: Vec<SpecsAndResolvedFeatures>,
    109}
    110
    111/// Pair of package specs requested for compilation along with enabled features.
    112pub struct SpecsAndResolvedFeatures {
    113    /// Packages that are supposed to be built.
    114    pub specs: Vec<PackageIdSpec>,
    115    /// The features activated per package.
    116    pub resolved_features: ResolvedFeatures,
    117}
    118
    119const UNUSED_PATCH_WARNING: &str = "\
    120Check that the patched package version and available features are compatible
    121with the dependency requirements. If the patch has a different version from
    122what is locked in the Cargo.lock file, run `cargo update` to use the new
    123version. This may also occur with an optional dependency that is not enabled.";
    124
    125/// Resolves all dependencies for the workspace using the previous
    126/// lock file as a guide if present.
    127///
    128/// This function will also write the result of resolution as a new lock file
    129/// (unless it is an ephemeral workspace such as `cargo install` or `cargo
    130/// package`).
    131///
    132/// This is a simple interface used by commands like `clean`, `fetch`, and
    133/// `package`, which don't specify any options or features.
    134pub fn resolve_ws<'a>(ws: &Workspace<'a>, dry_run: bool) -> CargoResult<(PackageSet<'a>, Resolve)> {
    135    let mut registry = ws.package_registry()?;
    136    let resolve = resolve_with_registry(ws, &mut registry, dry_run)?;
    137    let packages = get_resolved_packages(&resolve, registry)?;
    138    Ok((packages, resolve))
    139}
    140
    141/// Resolves dependencies for some packages of the workspace,
    142/// taking into account `paths` overrides and activated features.
    143///
    144/// This function will also write the result of resolution as a new lock file
    145/// (unless `Workspace::require_optional_deps` is false, such as `cargo
    146/// install` or `-Z avoid-dev-deps`), or it is an ephemeral workspace (`cargo
    147/// install` or `cargo package`).
    148///
    149/// `specs` may be empty, which indicates it should resolve all workspace
    150/// members. In this case, `opts.all_features` must be `true`.
    151pub fn resolve_ws_with_opts<'gctx>(
    152    ws: &Workspace<'gctx>,
    153    target_data: &mut RustcTargetData<'gctx>,
    154    requested_targets: &[CompileKind],
    155    cli_features: &CliFeatures,
    156    specs: &[PackageIdSpec],
    157    has_dev_units: HasDevUnits,
    158    force_all_targets: ForceAllTargets,
    159    dry_run: bool,
    160) -> CargoResult<WorkspaceResolve<'gctx>> {
    161    let feature_unification = ws.resolve_feature_unification();
    162    let individual_specs = match feature_unification {
    163        FeatureUnification::Selected => vec![specs.to_owned()],
    164        FeatureUnification::Workspace => {
    165            vec![ops::Packages::All(Vec::new()).to_package_id_specs(ws)?]
    166        }
    167        FeatureUnification::Package => specs.iter().map(|spec| vec![spec.clone()]).collect(),
    168    };
    169    let specs: Vec<_> = individual_specs
    170        .iter()
    171        .map(|specs| specs.iter())
    172        .flatten()
    173        .cloned()
    174        .collect();
    175    let specs = &specs[..];
    176    let mut registry = ws.package_registry()?;
    177    let (resolve, resolved_with_overrides) = if ws.ignore_lock() {
    178        let add_patches = true;
    179        let resolve = None;
    180        let resolved_with_overrides = resolve_with_previous(
    181            &mut registry,
    182            ws,
    183            cli_features,
    184            has_dev_units,
    185            resolve.as_ref(),
    186            None,
    187            specs,
    188            add_patches,
    189        )?;
    190        ops::print_lockfile_changes(ws, None, &resolved_with_overrides, &mut registry)?;
    191        (resolve, resolved_with_overrides)
    192    } else if ws.require_optional_deps() {
    193        // First, resolve the root_package's *listed* dependencies, as well as
    194        // downloading and updating all remotes and such.
    195        let resolve = resolve_with_registry(ws, &mut registry, dry_run)?;
    196        // No need to add patches again, `resolve_with_registry` has done it.
    197        let add_patches = false;
    198
    199        // Second, resolve with precisely what we're doing. Filter out
    200        // transitive dependencies if necessary, specify features, handle
    201        // overrides, etc.
    202        add_overrides(&mut registry, ws)?;
    203
    204        for (replace_spec, dep) in ws.root_replace() {
    205            if !resolve
    206                .iter()
    207                .any(|r| replace_spec.matches(r) && !dep.matches_id(r))
    208            {
    209                ws.gctx()
    210                    .shell()
    211                    .warn(format!("package replacement is not used: {}", replace_spec))?
    212            }
    213
    214            let mut unused_fields = Vec::new();
    215            if dep.features().len() != 0 {
    216                unused_fields.push("`features`");
    217            }
    218            if !dep.uses_default_features() {
    219                unused_fields.push("`default-features`")
    220            }
    221            if !unused_fields.is_empty() {
    222                ws.gctx().shell().print_report(
    223                    &[Level::WARNING
    224                        .secondary_title(format!(
    225                            "unused field in replacement for `{}`: {}",
    226                            dep.package_name(),
    227                            unused_fields.join(", ")
    228                        ))
    229                        .element(Level::NOTE.message(format!(
    230                            "configure {} in the `dependencies` entry",
    231                            unused_fields.join(", ")
    232                        )))],
    233                    false,
    234                )?;
    235            }
    236        }
    237
    238        let resolved_with_overrides = resolve_with_previous(
    239            &mut registry,
    240            ws,
    241            cli_features,
    242            has_dev_units,
    243            Some(&resolve),
    244            None,
    245            specs,
    246            add_patches,
    247        )?;
    248        (Some(resolve), resolved_with_overrides)
    249    } else {
    250        let add_patches = true;
    251        let resolve = ops::load_pkg_lockfile(ws)?;
    252        let resolved_with_overrides = resolve_with_previous(
    253            &mut registry,
    254            ws,
    255            cli_features,
    256            has_dev_units,
    257            resolve.as_ref(),
    258            None,
    259            specs,
    260            add_patches,
    261        )?;
    262        // Skipping `print_lockfile_changes` as there are cases where this prints irrelevant
    263        // information
    264        (resolve, resolved_with_overrides)
    265    };
    266
    267    let pkg_set = get_resolved_packages(&resolved_with_overrides, registry)?;
    268
    269    let members_with_features = ws.members_with_features(specs, cli_features)?;
    270    let member_ids = members_with_features
    271        .iter()
    272        .map(|(p, _fts)| p.package_id())
    273        .collect::<Vec<_>>();
    274    pkg_set.download_accessible(
    275        &resolved_with_overrides,
    276        &member_ids,
    277        has_dev_units,
    278        requested_targets,
    279        target_data,
    280        force_all_targets,
    281    )?;
    282
    283    let mut specs_and_features = Vec::new();
    284
    285    for specs in individual_specs {
    286        let feature_opts = FeatureOpts::new(ws, has_dev_units, force_all_targets)?;
    287
    288        // We want to narrow the features to the current specs so that stuff like `cargo check -p a
    289        // -p b -F a/a,b/b` works and the resolver does not contain that `a` does not have feature
    290        // `b` and vice-versa. However, resolver v1 needs to see even features of unselected
    291        // packages turned on if it was because of working directory being inside the unselected
    292        // package, because they might turn on a feature of a selected package.
    293        let narrowed_features = match feature_unification {
    294            FeatureUnification::Package => {
    295                let mut narrowed_features = cli_features.clone();
    296                let enabled_features = members_with_features
    297                    .iter()
    298                    .filter_map(|(package, cli_features)| {
    299                        specs
    300                            .iter()
    301                            .any(|spec| spec.matches(package.package_id()))
    302                            .then_some(cli_features.features.iter())
    303                    })
    304                    .flatten()
    305                    .cloned()
    306                    .collect();
    307                narrowed_features.features = Rc::new(enabled_features);
    308                Cow::Owned(narrowed_features)
    309            }
    310            FeatureUnification::Selected | FeatureUnification::Workspace => {
    311                Cow::Borrowed(cli_features)
    312            }
    313        };
    314
    315        let resolved_features = FeatureResolver::resolve(
    316            ws,
    317            target_data,
    318            &resolved_with_overrides,
    319            &pkg_set,
    320            &*narrowed_features,
    321            &specs,
    322            requested_targets,
    323            feature_opts,
    324        )?;
    325
    326        pkg_set.warn_no_lib_packages_and_artifact_libs_overlapping_deps(
    327            ws,
    328            &resolved_with_overrides,
    329            &member_ids,
    330            has_dev_units,
    331            requested_targets,
    332            target_data,
    333            force_all_targets,
    334        )?;
    335
    336        specs_and_features.push(SpecsAndResolvedFeatures {
    337            specs,
    338            resolved_features,
    339        });
    340    }
    341
    342    Ok(WorkspaceResolve {
    343        pkg_set,
    344        workspace_resolve: resolve,
    345        targeted_resolve: resolved_with_overrides,
    346        specs_and_features,
    347    })
    348}
    349
    350#[tracing::instrument(skip_all)]
    351fn resolve_with_registry<'gctx>(
    352    ws: &Workspace<'gctx>,
    353    registry: &mut PackageRegistry<'gctx>,
    354    dry_run: bool,
    355) -> CargoResult<Resolve> {
    356    let prev = ops::load_pkg_lockfile(ws)?;
    357    let mut resolve = resolve_with_previous(
    358        registry,
    359        ws,
    360        &CliFeatures::new_all(true),
    361        HasDevUnits::Yes,
    362        prev.as_ref(),
    363        None,
    364        &[],
    365        true,
    366    )?;
    367
    368    let print = if !ws.is_ephemeral() && ws.require_optional_deps() {
    369        if !dry_run {
    370            ops::write_pkg_lockfile(ws, &mut resolve)?
    371        } else {
    372            true
    373        }
    374    } else {
    375        // This mostly represents
    376        // - `cargo install --locked` and the only change is the package is no longer local but
    377        //   from the registry which is noise
    378        // - publish of libraries
    379        false
    380    };
    381    if print {
    382        ops::print_lockfile_changes(ws, prev.as_ref(), &resolve, registry)?;
    383    }
    384    Ok(resolve)
    385}
    386
    387/// Resolves all dependencies for a package using an optional previous instance
    388/// of resolve to guide the resolution process.
    389///
    390/// This also takes an optional filter `keep_previous`, which informs the `registry`
    391/// which package ID should be locked to the previous instance of resolve
    392/// (often used in pairings with updates). See comments in [`register_previous_locks`]
    393/// for scenarios that might override this.
    394///
    395/// The previous resolve normally comes from a lock file. This function does not
    396/// read or write lock files from the filesystem.
    397///
    398/// `specs` may be empty, which indicates it should resolve all workspace
    399/// members. In this case, `opts.all_features` must be `true`.
    400///
    401/// If `register_patches` is true, then entries from the `[patch]` table in
    402/// the manifest will be added to the given `PackageRegistry`.
    403#[tracing::instrument(skip_all)]
    404pub fn resolve_with_previous<'gctx>(
    405    registry: &mut PackageRegistry<'gctx>,
    406    ws: &Workspace<'gctx>,
    407    cli_features: &CliFeatures,
    408    has_dev_units: HasDevUnits,
    409    previous: Option<&Resolve>,
    410    keep_previous: Option<Keep<'_>>,
    411    specs: &[PackageIdSpec],
    412    register_patches: bool,
    413) -> CargoResult<Resolve> {
    414    // We only want one Cargo at a time resolving a crate graph since this can
    415    // involve a lot of frobbing of the global caches.
    416    let _lock = ws
    417        .gctx()
    418        .acquire_package_cache_lock(CacheLockMode::DownloadExclusive)?;
    419
    420    // Some packages are already loaded when setting up a workspace. This
    421    // makes it so anything that was already loaded will not be loaded again.
    422    // Without this there were cases where members would be parsed multiple times
    423    ws.preload(registry);
    424
    425    // In case any members were not already loaded or the Workspace is_ephemeral.
    426    for member in ws.members() {
    427        registry.add_sources(Some(member.package_id().source_id()))?;
    428    }
    429
    430    // Try to keep all from previous resolve if no instruction given.
    431    let keep_previous = keep_previous.unwrap_or(&|_| true);
    432
    433    // While registering patches, we will record preferences for particular versions
    434    // of various packages.
    435    let mut version_prefs = VersionPreferences::default();
    436    if ws.gctx().cli_unstable().minimal_versions {
    437        version_prefs.version_ordering(VersionOrdering::MinimumVersionsFirst)
    438    }
    439    if ws.resolve_honors_rust_version() {
    440        let mut rust_versions: Vec<_> = ws
    441            .members()
    442            .filter_map(|p| p.rust_version().map(|rv| rv.as_partial().clone()))
    443            .collect();
    444        if rust_versions.is_empty() {
    445            let rustc = ws.gctx().load_global_rustc(Some(ws))?;
    446            let rust_version: PartialVersion = rustc.version.clone().into();
    447            rust_versions.push(rust_version);
    448        }
    449        version_prefs.rust_versions(rust_versions);
    450    }
    451
    452    let avoid_patch_ids = if register_patches {
    453        register_patch_entries(registry, ws, previous, &mut version_prefs, keep_previous)?
    454    } else {
    455        HashSet::new()
    456    };
    457
    458    // Refine `keep` with patches that should avoid locking.
    459    let keep = |p: &PackageId| keep_previous(p) && !avoid_patch_ids.contains(p);
    460
    461    let dev_deps = ws.require_optional_deps() || has_dev_units == HasDevUnits::Yes;
    462
    463    if let Some(r) = previous {
    464        trace!("previous: {:?}", r);
    465
    466        // In the case where a previous instance of resolve is available, we
    467        // want to lock as many packages as possible to the previous version
    468        // without disturbing the graph structure.
    469        register_previous_locks(ws, registry, r, &keep, dev_deps);
    470
    471        // Prefer to use anything in the previous lock file, aka we want to have conservative updates.
    472        let _span = tracing::span!(tracing::Level::TRACE, "prefer_package_id").entered();
    473        for id in r.iter().filter(keep) {
    474            debug!("attempting to prefer {}", id);
    475            version_prefs.prefer_package_id(id);
    476        }
    477    }
    478
    479    if register_patches {
    480        registry.lock_patches();
    481    }
    482
    483    let summaries: Vec<(Summary, ResolveOpts)> = {
    484        let _span = tracing::span!(tracing::Level::TRACE, "registry.lock").entered();
    485        ws.members_with_features(specs, cli_features)?
    486            .into_iter()
    487            .map(|(member, features)| {
    488                let summary = registry.lock(member.summary().clone());
    489                (
    490                    summary,
    491                    ResolveOpts {
    492                        dev_deps,
    493                        features: RequestedFeatures::CliFeatures(features),
    494                    },
    495                )
    496            })
    497            .collect()
    498    };
    499
    500    let replace = lock_replacements(ws, previous, &keep);
    501
    502    let mut resolved = resolver::resolve(
    503        &summaries,
    504        &replace,
    505        registry,
    506        &version_prefs,
    507        ResolveVersion::with_rust_version(ws.lowest_rust_version()),
    508        Some(ws.gctx()),
    509    )?;
    510
    511    let patches = registry.patches().values().flat_map(|v| v.iter());
    512    resolved.register_used_patches(patches);
    513
    514    if register_patches && !resolved.unused_patches().is_empty() {
    515        emit_warnings_of_unused_patches(ws, &resolved, registry)?;
    516    }
    517
    518    if let Some(previous) = previous {
    519        resolved.merge_from(previous)?;
    520    }
    521    let gctx = ws.gctx();
    522    let mut deferred = gctx.deferred_global_last_use()?;
    523    deferred.save_no_error(gctx);
    524    Ok(resolved)
    525}
    526
    527/// Read the `paths` configuration variable to discover all path overrides that
    528/// have been configured.
    529#[tracing::instrument(skip_all)]
    530pub fn add_overrides<'a>(
    531    registry: &mut PackageRegistry<'a>,
    532    ws: &Workspace<'a>,
    533) -> CargoResult<()> {
    534    let gctx = ws.gctx();
    535    let Some(paths) = gctx.paths_overrides()? else {
    536        return Ok(());
    537    };
    538
    539    let paths = paths.val.iter().map(|(s, def)| {
    540        // The path listed next to the string is the config file in which the
    541        // key was located, so we want to pop off the `.cargo/config` component
    542        // to get the directory containing the `.cargo` folder.
    543        (paths::normalize_path(&def.root(gctx).join(s)), def)
    544    });
    545
    546    for (path, definition) in paths {
    547        let id = SourceId::for_path(&path)?;
    548        let mut source = RecursivePathSource::new(&path, id, ws.gctx());
    549        source.load().with_context(|| {
    550            format!(
    551                "failed to update path override `{}` \
    552                 (defined in `{}`)",
    553                path.display(),
    554                definition
    555            )
    556        })?;
    557        registry.add_override(Box::new(source));
    558    }
    559    Ok(())
    560}
    561
    562pub fn get_resolved_packages<'gctx>(
    563    resolve: &Resolve,
    564    registry: PackageRegistry<'gctx>,
    565) -> CargoResult<PackageSet<'gctx>> {
    566    let ids: Vec<PackageId> = resolve.iter().collect();
    567    registry.get(&ids)
    568}
    569
    570/// In this function we're responsible for informing the `registry` of all
    571/// locked dependencies from the previous lock file we had, `resolve`.
    572///
    573/// This gets particularly tricky for a couple of reasons. The first is that we
    574/// want all updates to be conservative, so we actually want to take the
    575/// `resolve` into account (and avoid unnecessary registry updates and such).
    576/// the second, however, is that we want to be resilient to updates of
    577/// manifests. For example if a dependency is added or a version is changed we
    578/// want to make sure that we properly re-resolve (conservatively) instead of
    579/// providing an opaque error.
    580///
    581/// The logic here is somewhat subtle, but there should be more comments below to
    582/// clarify things.
    583///
    584/// Note that this function, at the time of this writing, is basically the
    585/// entire fix for issue #4127.
    586#[tracing::instrument(skip_all)]
    587fn register_previous_locks(
    588    ws: &Workspace<'_>,
    589    registry: &mut PackageRegistry<'_>,
    590    resolve: &Resolve,
    591    keep: Keep<'_>,
    592    dev_deps: bool,
    593) {
    594    let path_pkg = |id: SourceId| {
    595        if !id.is_path() {
    596            return None;
    597        }
    598        if let Ok(path) = id.url().to_file_path() {
    599            if let Ok(pkg) = ws.load(&path.join("Cargo.toml")) {
    600                return Some(pkg);
    601            }
    602        }
    603        None
    604    };
    605
    606    // Ok so we've been passed in a `keep` function which basically says "if I
    607    // return `true` then this package wasn't listed for an update on the command
    608    // line". That is, if we run `cargo update foo` then `keep(bar)` will return
    609    // `true`, whereas `keep(foo)` will return `false` (roughly speaking).
    610    //
    611    // This isn't actually quite what we want, however. Instead we want to
    612    // further refine this `keep` function with *all transitive dependencies* of
    613    // the packages we're not keeping. For example, consider a case like this:
    614    //
    615    // * There's a crate `log`.
    616    // * There's a crate `serde` which depends on `log`.
    617    //
    618    // Let's say we then run `cargo update serde`. This may *also* want to
    619    // update the `log` dependency as our newer version of `serde` may have a
    620    // new minimum version required for `log`. Now this isn't always guaranteed
    621    // to work. What'll happen here is we *won't* lock the `log` dependency nor
    622    // the `log` crate itself, but we will inform the registry "please prefer
    623    // this version of `log`". That way if our newer version of serde works with
    624    // the older version of `log`, we conservatively won't update `log`. If,
    625    // however, nothing else in the dependency graph depends on `log` and the
    626    // newer version of `serde` requires a new version of `log` it'll get pulled
    627    // in (as we didn't accidentally lock it to an old version).
    628    let mut avoid_locking = HashSet::new();
    629    registry.add_to_yanked_whitelist(resolve.iter().filter(keep));
    630    for node in resolve.iter() {
    631        if !keep(&node) {
    632            add_deps(resolve, node, &mut avoid_locking);
    633        }
    634    }
    635
    636    // Ok, but the above loop isn't the entire story! Updates to the dependency
    637    // graph can come from two locations, the `cargo update` command or
    638    // manifests themselves. For example a manifest on the filesystem may
    639    // have been updated to have an updated version requirement on `serde`. In
    640    // this case both `keep(serde)` and `keep(log)` return `true` (the `keep`
    641    // that's an argument to this function). We, however, don't want to keep
    642    // either of those! Otherwise we'll get obscure resolve errors about locked
    643    // versions.
    644    //
    645    // To solve this problem we iterate over all packages with path sources
    646    // (aka ones with manifests that are changing) and take a look at all of
    647    // their dependencies. If any dependency does not match something in the
    648    // previous lock file, then we're guaranteed that the main resolver will
    649    // update the source of this dependency no matter what. Knowing this we
    650    // poison all packages from the same source, forcing them all to get
    651    // updated.
    652    //
    653    // This may seem like a heavy hammer, and it is! It means that if you change
    654    // anything from crates.io then all of crates.io becomes unlocked. Note,
    655    // however, that we still want conservative updates. This currently happens
    656    // because the first candidate the resolver picks is the previously locked
    657    // version, and only if that fails to activate to we move on and try
    658    // a different version. (giving the guise of conservative updates)
    659    //
    660    // For example let's say we had `serde = "0.1"` written in our lock file.
    661    // When we later edit this to `serde = "0.1.3"` we don't want to lock serde
    662    // at its old version, 0.1.1. Instead we want to allow it to update to
    663    // `0.1.3` and update its own dependencies (like above). To do this *all
    664    // crates from crates.io* are not locked (aka added to `avoid_locking`).
    665    // For dependencies like `log` their previous version in the lock file will
    666    // come up first before newer version, if newer version are available.
    667    {
    668        let _span = tracing::span!(tracing::Level::TRACE, "poison").entered();
    669        let mut path_deps = ws.members().cloned().collect::<Vec<_>>();
    670        let mut visited = HashSet::new();
    671        while let Some(member) = path_deps.pop() {
    672            if !visited.insert(member.package_id()) {
    673                continue;
    674            }
    675            let is_ws_member = ws.is_member(&member);
    676            for dep in member.dependencies() {
    677                // If this dependency didn't match anything special then we may want
    678                // to poison the source as it may have been added. If this path
    679                // dependencies is **not** a workspace member, however, and it's an
    680                // optional/non-transitive dependency then it won't be necessarily
    681                // be in our lock file. If this shows up then we avoid poisoning
    682                // this source as otherwise we'd repeatedly update the registry.
    683                //
    684                // TODO: this breaks adding an optional dependency in a
    685                // non-workspace member and then simultaneously editing the
    686                // dependency on that crate to enable the feature. For now,
    687                // this bug is better than the always-updating registry though.
    688                if !is_ws_member && (dep.is_optional() || !dep.is_transitive()) {
    689                    continue;
    690                }
    691
    692                // If dev-dependencies aren't being resolved, skip them.
    693                if !dep.is_transitive() && !dev_deps {
    694                    continue;
    695                }
    696
    697                // If this is a path dependency, then try to push it onto our
    698                // worklist.
    699                if let Some(pkg) = path_pkg(dep.source_id()) {
    700                    path_deps.push(pkg);
    701                    continue;
    702                }
    703
    704                // If we match *anything* in the dependency graph then we consider
    705                // ourselves all ok, and assume that we'll resolve to that.
    706                if resolve.iter().any(|id| dep.matches_ignoring_source(id)) {
    707                    continue;
    708                }
    709
    710                // Ok if nothing matches, then we poison the source of these
    711                // dependencies and the previous lock file.
    712                debug!(
    713                    "poisoning {} because {} looks like it changed {}",
    714                    dep.source_id(),
    715                    member.package_id(),
    716                    dep.package_name()
    717                );
    718                for id in resolve
    719                    .iter()
    720                    .filter(|id| id.source_id() == dep.source_id())
    721                {
    722                    add_deps(resolve, id, &mut avoid_locking);
    723                }
    724            }
    725        }
    726    }
    727
    728    // Additionally, here we process all path dependencies listed in the previous
    729    // resolve. They can not only have their dependencies change but also
    730    // the versions of the package change as well. If this ends up happening
    731    // then we want to make sure we don't lock a package ID node that doesn't
    732    // actually exist. Note that we don't do transitive visits of all the
    733    // package's dependencies here as that'll be covered below to poison those
    734    // if they changed.
    735    //
    736    // This must come after all other `add_deps` calls to ensure it recursively walks the tree when
    737    // called.
    738    for node in resolve.iter() {
    739        if let Some(pkg) = path_pkg(node.source_id()) {
    740            if pkg.package_id() != node {
    741                avoid_locking.insert(node);
    742            }
    743        }
    744    }
    745
    746    // Alright now that we've got our new, fresh, shiny, and refined `keep`
    747    // function let's put it to action. Take a look at the previous lock file,
    748    // filter everything by this callback, and then shove everything else into
    749    // the registry as a locked dependency.
    750    let keep = |id: &PackageId| keep(id) && !avoid_locking.contains(id);
    751
    752    registry.clear_lock();
    753    {
    754        let _span = tracing::span!(tracing::Level::TRACE, "register_lock").entered();
    755        for node in resolve.iter().filter(keep) {
    756            let deps = resolve
    757                .deps_not_replaced(node)
    758                .map(|p| p.0)
    759                .filter(keep)
    760                .collect::<Vec<_>>();
    761
    762            // In the v2 lockfile format and prior the `branch=master` dependency
    763            // directive was serialized the same way as the no-branch-listed
    764            // directive. Nowadays in Cargo, however, these two directives are
    765            // considered distinct and are no longer represented the same way. To
    766            // maintain compatibility with older lock files we register locked nodes
    767            // for *both* the master branch and the default branch.
    768            //
    769            // Note that this is only applicable for loading older resolves now at
    770            // this point. All new lock files are encoded as v3-or-later, so this is
    771            // just compat for loading an old lock file successfully.
    772            if let Some(node) = master_branch_git_source(node, resolve) {
    773                registry.register_lock(node, deps.clone());
    774            }
    775
    776            registry.register_lock(node, deps);
    777        }
    778    }
    779
    780    /// Recursively add `node` and all its transitive dependencies to `set`.
    781    fn add_deps(resolve: &Resolve, node: PackageId, set: &mut HashSet<PackageId>) {
    782        if !set.insert(node) {
    783            return;
    784        }
    785        debug!("ignoring any lock pointing directly at {}", node);
    786        for (dep, _) in resolve.deps_not_replaced(node) {
    787            add_deps(resolve, dep, set);
    788        }
    789    }
    790}
    791
    792fn master_branch_git_source(id: PackageId, resolve: &Resolve) -> Option<PackageId> {
    793    if resolve.version() <= ResolveVersion::V2 {
    794        let source = id.source_id();
    795        if let Some(GitReference::DefaultBranch) = source.git_reference() {
    796            let new_source =
    797                SourceId::for_git(source.url(), GitReference::Branch("master".to_string()))
    798                    .unwrap()
    799                    .with_precise_from(source);
    800            return Some(id.with_source_id(new_source));
    801        }
    802    }
    803    None
    804}
    805
    806/// Emits warnings of unused patches case by case.
    807///
    808/// This function does its best to provide more targeted and helpful
    809/// (such as showing close candidates that failed to match). However, that's
    810/// not terribly easy to do, so just show a general help message if we cannot.
    811fn emit_warnings_of_unused_patches(
    812    ws: &Workspace<'_>,
    813    resolve: &Resolve,
    814    registry: &PackageRegistry<'_>,
    815) -> CargoResult<()> {
    816    const MESSAGE: &str = "was not used in the crate graph";
    817
    818    // Patch package with the source URLs being patch
    819    let mut patch_pkgid_to_urls = HashMap::new();
    820    for (url, summaries) in registry.patches().iter() {
    821        for summary in summaries.iter() {
    822            patch_pkgid_to_urls
    823                .entry(summary.package_id())
    824                .or_insert_with(HashSet::new)
    825                .insert(url);
    826        }
    827    }
    828
    829    // pkg name -> all source IDs of under the same pkg name
    830    let mut source_ids_grouped_by_pkg_name = HashMap::new();
    831    for pkgid in resolve.iter() {
    832        source_ids_grouped_by_pkg_name
    833            .entry(pkgid.name())
    834            .or_insert_with(HashSet::new)
    835            .insert(pkgid.source_id());
    836    }
    837
    838    let mut unemitted_unused_patches = Vec::new();
    839    for unused in resolve.unused_patches().iter() {
    840        // Show alternative source URLs if the source URLs being patched
    841        // cannot be found in the crate graph.
    842        match (
    843            source_ids_grouped_by_pkg_name.get(&unused.name()),
    844            patch_pkgid_to_urls.get(unused),
    845        ) {
    846            (Some(ids), Some(patched_urls))
    847                if ids
    848                    .iter()
    849                    .all(|id| !patched_urls.contains(id.canonical_url())) =>
    850            {
    851                let mut help = "perhaps you meant one of the following:".to_owned();
    852                for id in ids {
    853                    help.push_str("\n\t");
    854                    help.push_str(&id.display_registry_name());
    855                }
    856                ws.gctx().shell().print_report(
    857                    &[Level::WARNING
    858                        .secondary_title(format!("patch `{unused}` {MESSAGE}"))
    859                        .element(Level::HELP.message(help))],
    860                    false,
    861                )?;
    862            }
    863            _ => unemitted_unused_patches.push(unused),
    864        }
    865    }
    866
    867    // Show general help message.
    868    if !unemitted_unused_patches.is_empty() {
    869        let mut warnings: Vec<_> = unemitted_unused_patches
    870            .iter()
    871            .map(|pkgid| {
    872                Group::with_title(
    873                    Level::WARNING.secondary_title(format!("patch `{pkgid}` {MESSAGE}")),
    874                )
    875            })
    876            .collect();
    877        warnings.push(Group::with_title(
    878            Level::HELP.secondary_title(UNUSED_PATCH_WARNING),
    879        ));
    880        ws.gctx().shell().print_report(&warnings, false)?;
    881    }
    882
    883    return Ok(());
    884}
    885
    886/// Informs `registry` and `version_pref` that `[patch]` entries are available
    887/// and preferable for the dependency resolution.
    888///
    889/// This returns a set of PackageIds of `[patch]` entries, and some related
    890/// locked PackageIds, for which locking should be avoided (but which will be
    891/// preferred when searching dependencies, via [`VersionPreferences::prefer_patch_deps`]).
    892#[tracing::instrument(level = "debug", skip_all, ret)]
    893fn register_patch_entries(
    894    registry: &mut PackageRegistry<'_>,
    895    ws: &Workspace<'_>,
    896    previous: Option<&Resolve>,
    897    version_prefs: &mut VersionPreferences,
    898    keep_previous: Keep<'_>,
    899) -> CargoResult<HashSet<PackageId>> {
    900    let mut avoid_patch_ids = HashSet::new();
    901    for (url, patches) in ws.root_patch()?.iter() {
    902        for patch in patches {
    903            version_prefs.prefer_dependency(patch.clone());
    904        }
    905        let Some(previous) = previous else {
    906            let patches: Vec<_> = patches.iter().map(|p| (p, None)).collect();
    907            let unlock_ids = registry.patch(url, &patches)?;
    908            // Since nothing is locked, this shouldn't possibly return anything.
    909            assert!(unlock_ids.is_empty());
    910            continue;
    911        };
    912
    913        // This is a list of pairs where the first element of the pair is
    914        // the raw `Dependency` which matches what's listed in `Cargo.toml`.
    915        // The second element is, if present, the "locked" version of
    916        // the `Dependency` as well as the `PackageId` that it previously
    917        // resolved to. This second element is calculated by looking at the
    918        // previous resolve graph, which is primarily what's done here to
    919        // build the `registrations` list.
    920        let mut registrations = Vec::new();
    921        for dep in patches {
    922            let candidates = || {
    923                previous
    924                    .iter()
    925                    .chain(previous.unused_patches().iter().cloned())
    926                    .filter(&keep_previous)
    927            };
    928
    929            let lock = match candidates().find(|id| dep.matches_id(*id)) {
    930                // If we found an exactly matching candidate in our list of
    931                // candidates, then that's the one to use.
    932                Some(package_id) => {
    933                    let mut locked_dep = dep.clone();
    934                    locked_dep.lock_to(package_id);
    935                    Some(LockedPatchDependency {
    936                        dependency: locked_dep,
    937                        package_id,
    938                        alt_package_id: None,
    939                    })
    940                }
    941                None => {
    942                    // If the candidate does not have a matching source id
    943                    // then we may still have a lock candidate. If we're
    944                    // loading a v2-encoded resolve graph and `dep` is a
    945                    // git dep with `branch = 'master'`, then this should
    946                    // also match candidates without `branch = 'master'`
    947                    // (which is now treated separately in Cargo).
    948                    //
    949                    // In this scenario we try to convert candidates located
    950                    // in the resolve graph to explicitly having the
    951                    // `master` branch (if they otherwise point to
    952                    // `DefaultBranch`). If this works and our `dep`
    953                    // matches that then this is something we'll lock to.
    954                    match candidates().find(|&id| match master_branch_git_source(id, previous) {
    955                        Some(id) => dep.matches_id(id),
    956                        None => false,
    957                    }) {
    958                        Some(id_using_default) => {
    959                            let id_using_master = id_using_default.with_source_id(
    960                                dep.source_id()
    961                                    .with_precise_from(id_using_default.source_id()),
    962                            );
    963
    964                            let mut locked_dep = dep.clone();
    965                            locked_dep.lock_to(id_using_master);
    966                            Some(LockedPatchDependency {
    967                                dependency: locked_dep,
    968                                package_id: id_using_master,
    969                                // Note that this is where the magic
    970                                // happens, where the resolve graph
    971                                // probably has locks pointing to
    972                                // DefaultBranch sources, and by including
    973                                // this here those will get transparently
    974                                // rewritten to Branch("master") which we
    975                                // have a lock entry for.
    976                                alt_package_id: Some(id_using_default),
    977                            })
    978                        }
    979
    980                        // No locked candidate was found
    981                        None => None,
    982                    }
    983                }
    984            };
    985
    986            registrations.push((dep, lock));
    987        }
    988
    989        let canonical = CanonicalUrl::new(url)?;
    990        for (orig_patch, unlock_id) in registry.patch(url, &registrations)? {
    991            // Avoid the locked patch ID.
    992            avoid_patch_ids.insert(unlock_id);
    993            // Also avoid the thing it is patching.
    994            avoid_patch_ids.extend(previous.iter().filter(|id| {
    995                orig_patch.matches_ignoring_source(*id)
    996                    && *id.source_id().canonical_url() == canonical
    997            }));
    998        }
    999    }
    1000
    1001    Ok(avoid_patch_ids)
    1002}
    1003
    1004/// Locks each `[replace]` entry to a specific Package ID
    1005/// if the lockfile contains any corresponding previous replacement.
    1006fn lock_replacements(
    1007    ws: &Workspace<'_>,
    1008    previous: Option<&Resolve>,
    1009    keep: Keep<'_>,
    1010) -> Vec<(PackageIdSpec, Dependency)> {
    1011    let root_replace = ws.root_replace();
    1012    let replace = match previous {
    1013        Some(r) => root_replace
    1014            .iter()
    1015            .map(|(spec, dep)| {
    1016                for (&key, &val) in r.replacements().iter() {
    1017                    if spec.matches(key) && dep.matches_id(val) && keep(&val) {
    1018                        let mut dep = dep.clone();
    1019                        dep.lock_to(val);
    1020                        return (spec.clone(), dep);
    1021                    }
    1022                }
    1023                (spec.clone(), dep.clone())
    1024            })
    1025            .collect::<Vec<_>>(),
    1026        None => root_replace.to_vec(),
    1027    };
    1028    replace
    1029}