feat: Implement cargo update --breaking.

crates/cargo-test-support/src/compare.rs

@@ -176,6 +176,7 @@ static E2E_LITERAL_REDACTIONS: &[(&str, &str)] = &[
     ("[DIRTY]", "       Dirty"),
     ("[LOCKING]", "     Locking"),
     ("[UPDATING]", "    Updating"),
+    ("[UPGRADING]", "   Upgrading"),
     ("[ADDING]", "      Adding"),
     ("[REMOVING]", "    Removing"),
     ("[REMOVED]", "     Removed"),

src/bin/cargo/commands/update.rs

@@ -35,6 +35,13 @@ pub fn cli() -> Command {
                 .value_name("PRECISE")
                 .requires("package-group"),
         )
+        .arg(
+            flag(
+                "breaking",
+                "Upgrade [SPEC] to latest breaking versions, unless pinned (unstable)",
+            )
+            .short('b'),
+        )
         .arg_silent_suggestion()
         .arg(
             flag("workspace", "Only update the workspace packages")
@@ -59,7 +66,8 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
             gctx.cli_unstable().msrv_policy,
         )?;
     }
-    let ws = args.workspace(gctx)?;
+
+    let mut ws = args.workspace(gctx)?;
 
     if args.is_present_with_zero_values("package") {
         print_available_packages(&ws)?;
@@ -84,11 +92,30 @@ pub fn exec(gctx: &mut GlobalContext, args: &ArgMatches) -> CliResult {
     let update_opts = UpdateOptions {
         recursive: args.flag("recursive"),
         precise: args.get_one::<String>("precise").map(String::as_str),
+        breaking: args.flag("breaking"),
         to_update,
         dry_run: args.dry_run(),
         workspace: args.flag("workspace"),
         gctx,
     };
-    ops::update_lockfile(&ws, &update_opts)?;
+
+    if update_opts.breaking {
+        gctx.cli_unstable()
+            .fail_if_stable_opt("--breaking", 12425)?;
+
+        let upgrades = ops::upgrade_manifests(&mut ws, &update_opts)?;
+        ops::resolve_ws(&ws, update_opts.dry_run)?;
+        ops::write_manifest_upgrades(&ws, &update_opts, &upgrades)?;
+
+        if update_opts.dry_run {
+            update_opts
+                .gctx
+                .shell()
+                .warn("aborting update due to dry run")?;
+        }
+    } else {
+        ops::update_lockfile(&ws, &update_opts)?;
+    }
+
     Ok(())
 }

src/cargo/core/summary.rs

@@ -103,15 +103,25 @@ impl Summary {
         Rc::make_mut(&mut self.inner).checksum = Some(cksum);
     }
 
-    pub fn map_dependencies<F>(mut self, f: F) -> Summary
+    pub fn map_dependencies<F>(self, mut f: F) -> Summary
     where
         F: FnMut(Dependency) -> Dependency,
+    {
+        self.try_map_dependencies(|dep| Ok(f(dep))).unwrap()
+    }
+
+    pub fn try_map_dependencies<F>(mut self, f: F) -> CargoResult<Summary>
+    where
+        F: FnMut(Dependency) -> CargoResult<Dependency>,
     {
         {
             let slot = &mut Rc::make_mut(&mut self.inner).dependencies;
-            *slot = mem::take(slot).into_iter().map(f).collect();
+            *slot = mem::take(slot)
+                .into_iter()
+                .map(f)
+                .collect::<CargoResult<_>>()?;
         }
-        self
+        Ok(self)
     }
 
     pub fn map_source(self, to_replace: SourceId, replace_with: SourceId) -> Summary {

src/cargo/ops/cargo_update.rs

@@ -1,3 +1,4 @@
+use crate::core::dependency::Dependency;
 use crate::core::registry::PackageRegistry;
 use crate::core::resolver::features::{CliFeatures, HasDevUnits};
 use crate::core::shell::Verbosity;
@@ -8,17 +9,25 @@ use crate::ops;
 use crate::sources::source::QueryKind;
 use crate::util::cache_lock::CacheLockMode;
 use crate::util::context::GlobalContext;
-use crate::util::style;
-use crate::util::CargoResult;
+use crate::util::toml_mut::dependency::{MaybeWorkspace, Source};
+use crate::util::toml_mut::manifest::LocalManifest;
+use crate::util::toml_mut::upgrade::upgrade_requirement;
+use crate::util::{style, OptVersionReq};
+use crate::util::{CargoResult, VersionExt};
+use itertools::Itertools;
+use semver::{Op, Version, VersionReq};
 use std::cmp::Ordering;
-use std::collections::{BTreeMap, HashSet};
-use tracing::debug;
+use std::collections::{BTreeMap, HashMap, HashSet};
+use tracing::{debug, trace};
+
+pub type UpgradeMap = HashMap<(String, SourceId), Version>;
 
 pub struct UpdateOptions<'a> {
     pub gctx: &'a GlobalContext,
     pub to_update: Vec<String>,
     pub precise: Option<&'a str>,
     pub recursive: bool,
+    pub breaking: bool,
     pub dry_run: bool,
     pub workspace: bool,
 }
@@ -207,6 +216,246 @@ pub fn print_lockfile_changes(
     }
 }
 
+pub fn upgrade_manifests(
+    ws: &mut Workspace<'_>,
+    opts: &UpdateOptions<'_>,
+) -> CargoResult<UpgradeMap> {
+    let mut upgrades = HashMap::new();
+    let mut upgrade_messages = HashSet::new();
+
+    // Updates often require a lot of modifications to the registry, so ensure
+    // that we're synchronized against other Cargos.
+    let _lock = ws
+        .gctx()
+        .acquire_package_cache_lock(CacheLockMode::DownloadExclusive)?;
+
+    let mut registry = PackageRegistry::new(opts.gctx)?;
+    registry.lock_patches();
+
+    for member in ws.members_mut().sorted() {
+        debug!("upgrading manifest for `{}`", member.name());
+
+        *member.manifest_mut().summary_mut() = member
+            .manifest()
+            .summary()
+            .clone()
+            .try_map_dependencies(|d| {
+                upgrade_dependency(&mut registry, &mut upgrades, &mut upgrade_messages, opts, d)
+            })?;
+    }
+
+    Ok(upgrades)
+}
+
+fn upgrade_dependency(
+    registry: &mut PackageRegistry<'_>,
+    upgrades: &mut UpgradeMap,
+    upgrade_messages: &mut HashSet<String>,
+    opts: &UpdateOptions<'_>,
+    dependency: Dependency,
+) -> CargoResult<Dependency> {
+    let name = dependency.package_name();
+    let renamed_to = dependency.name_in_toml();
+
+    if name != renamed_to {
+        trace!(
+            "skipping dependency renamed from `{}` to `{}`",
+            name,
+            renamed_to
+        );
+        return Ok(dependency);
+    }
+
+    if !opts.to_update.is_empty() && !opts.to_update.contains(&name.to_string()) {
+        trace!("skipping dependency `{}` not selected for upgrading", name);
+        return Ok(dependency);
+    }
+
+    if !dependency.source_id().is_registry() {
+        trace!("skipping non-registry dependency: {}", name);
+        return Ok(dependency);
+    }
+
+    let version_req = dependency.version_req();
+
+    let OptVersionReq::Req(current) = version_req else {
+        trace!(
+            "skipping dependency `{}` without a simple version requirement: {}",
+            name,
+            version_req
+        );
+        return Ok(dependency);
+    };
+
+    let [comparator] = &current.comparators[..] else {
+        trace!(
+            "skipping dependency `{}` with multiple version comparators: {:?}",
+            name,
+            &current.comparators
+        );
+        return Ok(dependency);
+    };
+
+    if comparator.op != Op::Caret {
+        trace!("skipping non-caret dependency `{}`: {}", name, comparator);
+        return Ok(dependency);
+    }
+
+    let query =
+        crate::core::dependency::Dependency::parse(name, None, dependency.source_id().clone())?;
+
+    let possibilities = {
+        loop {
+            match registry.query_vec(&query, QueryKind::Exact) {
+                std::task::Poll::Ready(res) => {
+                    break res?;
+                }
+                std::task::Poll::Pending => registry.block_until_ready()?,
+            }
+        }
+    };
+
+    let latest = if !possibilities.is_empty() {
+        possibilities
+            .iter()
+            .map(|s| s.as_summary())
+            .map(|s| s.version())
+            .filter(|v| !v.is_prerelease())
+            .max()
+    } else {
+        None
+    };
+
+    let Some(latest) = latest else {
+        trace!(
+            "skipping dependency `{}` without any published versions",
+            name
+        );
+        return Ok(dependency);
+    };
+
+    if current.matches(&latest) {
+        trace!(
+            "skipping dependency `{}` without a breaking update available",
+            name
+        );
+        return Ok(dependency);
+    }
+
+    let Some(new_req_string) = upgrade_requirement(&current.to_string(), latest)? else {
+        trace!(
+            "skipping dependency `{}` because the version requirement didn't change",
+            name
+        );
+        return Ok(dependency);
+    };
+
+    let upgrade_message = format!("{} {} -> {}", name, current, new_req_string);
+    trace!(upgrade_message);
+
+    if upgrade_messages.insert(upgrade_message.clone()) {
+        opts.gctx
+            .shell()
+            .status_with_color("Upgrading", &upgrade_message, &style::GOOD)?;
+    }
+
+    upgrades.insert((name.to_string(), dependency.source_id()), latest.clone());
+
+    let req = OptVersionReq::Req(VersionReq::parse(&latest.to_string())?);
+    let mut dep = dependency.clone();
+    dep.set_version_req(req);
+    Ok(dep)
+}
+
+/// Update manifests with upgraded versions, and write to disk. Based on cargo-edit.
+/// Returns true if any file has changed.
+pub fn write_manifest_upgrades(
+    ws: &Workspace<'_>,
+    opts: &UpdateOptions<'_>,
+    upgrades: &UpgradeMap,
+) -> CargoResult<bool> {
+    if upgrades.is_empty() {
+        return Ok(false);
+    }
+
+    let mut any_file_has_changed = false;
+
+    let manifest_paths = std::iter::once(ws.root_manifest())
+        .chain(ws.members().map(|member| member.manifest_path()))
+        .collect::<Vec<_>>();
+
+    for manifest_path in manifest_paths {
+        trace!(
+            "updating TOML manifest at `{:?}` with upgraded dependencies",
+            manifest_path
+        );
+
+        let crate_root = manifest_path
+            .parent()
+            .expect("manifest path is absolute")
+            .to_owned();
+
+        let mut local_manifest = LocalManifest::try_new(&manifest_path)?;
+        let mut manifest_has_changed = false;
+
+        for dep_table in local_manifest.get_dependency_tables_mut() {
+            for (mut dep_key, dep_item) in dep_table.iter_mut() {
+                let dep_key_str = dep_key.get();
+                let dependency = crate::util::toml_mut::dependency::Dependency::from_toml(
+                    &manifest_path,
+                    dep_key_str,
+                    dep_item,
+                )?;
+
+                let Some(current) = dependency.version() else {
+                    trace!("skipping dependency without a version: {}", dependency.name);
+                    continue;
+                };
+
+                let (MaybeWorkspace::Other(source_id), Some(Source::Registry(source))) =
+                    (dependency.source_id(opts.gctx)?, dependency.source())
+                else {
+                    trace!("skipping non-registry dependency: {}", dependency.name);
+                    continue;
+                };
+
+                let Some(latest) = upgrades.get(&(dependency.name.to_owned(), source_id)) else {
+                    trace!(
+                        "skipping dependency without an upgrade: {}",
+                        dependency.name
+                    );
+                    continue;
+                };
+
+                let Some(new_req_string) = upgrade_requirement(current, latest)? else {
+                    trace!(
+                        "skipping dependency `{}` because the version requirement didn't change",
+                        dependency.name
+                    );
+                    continue;
+                };
+
+                let mut dep = dependency.clone();
+                let mut source = source.clone();
+                source.version = new_req_string;
+                dep.source = Some(Source::Registry(source));
+
+                trace!("upgrading dependency {}", dependency.name);
+                dep.update_toml(&crate_root, &mut dep_key, dep_item);
+                manifest_has_changed = true;
+                any_file_has_changed = true;
+            }
+        }
+
+        if manifest_has_changed && !opts.dry_run {
+            debug!("writing upgraded manifest to {}", manifest_path.display());
+            local_manifest.write()?;
+        }
+    }
+
+    Ok(any_file_has_changed)
+}
+
 fn print_lockfile_generation(
     ws: &Workspace<'_>,
     resolve: &Resolve,

src/cargo/ops/mod.rs

@@ -19,6 +19,8 @@ pub use self::cargo_uninstall::uninstall;
 pub use self::cargo_update::generate_lockfile;
 pub use self::cargo_update::print_lockfile_changes;
 pub use self::cargo_update::update_lockfile;
+pub use self::cargo_update::upgrade_manifests;
+pub use self::cargo_update::write_manifest_upgrades;
 pub use self::cargo_update::UpdateOptions;
 pub use self::fix::{fix, fix_exec_rustc, fix_get_proxy_lock_addr, FixOptions};
 pub use self::lockfile::{load_pkg_lockfile, resolve_to_string, write_pkg_lockfile};