Read/write the encoded cargo update --precise in the same place

src/cargo/core/source/source_id.rs

@@ -2,7 +2,8 @@ use crate::core::PackageId;
 use crate::sources::registry::CRATES_IO_HTTP_INDEX;
 use crate::sources::{DirectorySource, CRATES_IO_DOMAIN, CRATES_IO_INDEX, CRATES_IO_REGISTRY};
 use crate::sources::{GitSource, PathSource, RegistrySource};
-use crate::util::{config, CanonicalUrl, CargoResult, Config, IntoUrl};
+use crate::util::{config, CanonicalUrl, CargoResult, Config, IntoUrl, ToSemver};
+use anyhow::Context;
 use serde::de;
 use serde::ser;
 use std::cmp::{self, Ordering};
@@ -430,11 +431,6 @@ impl SourceId {
         }
     }
 
-    /// Gets the value of the precise field.
-    pub fn precise(self) -> Option<&'static str> {
-        self.inner.precise.as_deref()
-    }
-
     /// Gets the Git reference if this is a git source, otherwise `None`.
     pub fn git_reference(self) -> Option<&'static GitReference> {
         match self.inner.kind {
@@ -443,6 +439,33 @@ impl SourceId {
         }
     }
 
+    /// Gets the value of the precise field.
+    pub fn precise(self) -> Option<&'static str> {
+        self.inner.precise.as_deref()
+    }
+
+    /// Check if the precise data field stores information for this `name`
+    /// from a call to [SourceId::with_precise_registry_version].
+    ///
+    /// If so return the version currently in the lock file and the version to be updated to.
+    /// If specified, our own source will have a precise version listed of the form
+    // `<pkg>=<p_req>-><f_req>` where `<pkg>` is the name of a crate on
+    // this source, `<p_req>` is the version installed and `<f_req>` is the
+    // version requested (argument to `--precise`).
+    pub fn precise_registry_version(
+        self,
+        name: &str,
+    ) -> Option<(semver::Version, semver::Version)> {
+        self.inner
+            .precise
+            .as_deref()
+            .and_then(|p| p.strip_prefix(name)?.strip_prefix('='))
+            .map(|p| {
+                let (current, requested) = p.split_once("->").unwrap();
+                (current.to_semver().unwrap(), requested.to_semver().unwrap())
+            })
+    }
+
     /// Creates a new `SourceId` from this source with the given `precise`.
     pub fn with_precise(self, v: Option<String>) -> SourceId {
         SourceId::wrap(SourceIdInner {
@@ -451,6 +474,23 @@ impl SourceId {
         })
     }
 
+    /// When updating a lock file on a version using `cargo update --precise`
+    /// the requested version is stored in the precise field.
+    /// On a registry dependency we also need to keep track of the package that
+    /// should be updated and even which of the versions should be updated.
+    /// All of this gets encoded in the precise field using this method.
+    /// The data can be read with [SourceId::precise_registry_version]
+    pub fn with_precise_registry_version(
+        self,
+        name: impl fmt::Display,
+        version: &semver::Version,
+        precise: &str,
+    ) -> CargoResult<SourceId> {
+        semver::Version::parse(precise)
+            .with_context(|| format!("invalid version format for precise version `{precise}`"))?;
+        Ok(self.with_precise(Some(format!("{}={}->{}", name, version, precise))))
+    }
+
     /// Returns `true` if the remote registry is the standard <https://crates.io>.
     pub fn is_crates_io(self) -> bool {
         match self.inner.kind {

src/cargo/ops/cargo_generate_lockfile.rs

@@ -5,7 +5,6 @@ use crate::core::{Resolve, SourceId, Workspace};
 use crate::ops;
 use crate::util::config::Config;
 use crate::util::CargoResult;
-use anyhow::Context;
 use std::collections::{BTreeMap, HashSet};
 use termcolor::Color::{self, Cyan, Green, Red, Yellow};
 use tracing::debug;
@@ -88,27 +87,27 @@ pub fn update_lockfile(ws: &Workspace<'_>, opts: &UpdateOptions<'_>) -> CargoRes
     } else {
         let mut sources = Vec::new();
         for name in opts.to_update.iter() {
-            let dep = previous_resolve.query(name)?;
+            let pid = previous_resolve.query(name)?;
             if opts.recursive {
-                fill_with_deps(&previous_resolve, dep, &mut to_avoid, &mut HashSet::new());
+                fill_with_deps(&previous_resolve, pid, &mut to_avoid, &mut HashSet::new());
             } else {
-                to_avoid.insert(dep);
+                to_avoid.insert(pid);
                 sources.push(match opts.precise {
                     Some(precise) => {
                         // TODO: see comment in `resolve.rs` as well, but this
                         //       seems like a pretty hokey reason to single out
                         //       the registry as well.
-                        let precise = if dep.source_id().is_registry() {
-                            semver::Version::parse(precise).with_context(|| {
-                                format!("invalid version format for precise version `{}`", precise)
-                            })?;
-                            format!("{}={}->{}", dep.name(), dep.version(), precise)
+                        if pid.source_id().is_registry() {
+                            pid.source_id().with_precise_registry_version(
+                                pid.name(),
+                                pid.version(),
+                                precise,
+                            )?
                         } else {
-                            precise.to_string()
-                        };
-                        dep.source_id().with_precise(Some(precise))
+                            pid.source_id().with_precise(Some(precise.to_string()))
+                        }
                     }
-                    None => dep.source_id().with_precise(None),
+                    None => pid.source_id().with_precise(None),
                 });
             }
             if let Ok(unused_id) =

src/cargo/sources/registry/index.rs

@@ -91,9 +91,7 @@ use crate::core::{PackageId, SourceId, Summary};
 use crate::sources::registry::{LoadResponse, RegistryData};
 use crate::util::interning::InternedString;
 use crate::util::IntoUrl;
-use crate::util::{
-    internal, CargoResult, Config, Filesystem, OptVersionReq, PartialVersion, ToSemver,
-};
+use crate::util::{internal, CargoResult, Config, Filesystem, OptVersionReq, PartialVersion};
 use anyhow::bail;
 use cargo_util::{paths, registry::make_dep_path};
 use semver::Version;
@@ -582,18 +580,8 @@ impl<'cfg> RegistryIndex<'cfg> {
             .filter(|s| !s.yanked || yanked_whitelist.contains(&s.summary.package_id()))
             .map(|s| s.summary.clone());
 
-        // Handle `cargo update --precise` here. If specified, our own source
-        // will have a precise version listed of the form
-        // `<pkg>=<p_req>o-><f_req>` where `<pkg>` is the name of a crate on
-        // this source, `<p_req>` is the version installed and `<f_req> is the
-        // version requested (argument to `--precise`).
-        let precise = source_id
-            .precise()
-            .filter(|p| p.starts_with(name) && p[name.len()..].starts_with('='))
-            .map(|p| {
-                let (current, requested) = p[name.len() + 1..].split_once("->").unwrap();
-                (current.to_semver().unwrap(), requested.to_semver().unwrap())
-            });
+        // Handle `cargo update --precise` here.
+        let precise = source_id.precise_registry_version(name);
         let summaries = summaries.filter(|s| match &precise {
             Some((current, requested)) => {
                 if req.matches(current) {