fix(resolver): Report invalid index entries

While rust-lang#14897 reported packages with an unsupported index schema version,
that only worked if the changes in the schema version did not cause
errors in deserializing `IndexPackage` or in generating a `Summary`.

This extends that change by recoverying on error with a more lax,
incomplete parse of `IndexPackage` which should always generate a valid
`Summary`.

To help with a buggy Index, we also will report as many as we can.
This does not provide a way to report to users or log on cache reads if
the index entry is not at least `{"name": "<string>", "vers": "<semver>"}`.

As a side effect, the index cache will include more "invalid" index
entries.
That should be ok as we will ignore the invalid entry in the cache when
loading it.
Ignoring of invalid entries dates back to rust-lang#6880 when the index cache was
introduced.

Fixes rust-lang#10623
Fixes rust-lang#14894

src/cargo/core/resolver/errors.rs

@@ -271,6 +271,13 @@ pub(super) fn activation_error(
                         );
                     }
                 }
+                IndexSummary::Invalid(summary) => {
+                    let _ = writeln!(
+                        &mut msg,
+                        "  version {}'s index entry is invalid",
+                        summary.version()
+                    );
+                }
             }
         }
     } else if let Some(candidates) = alt_versions(registry, dep) {

src/cargo/sources/registry/index/mod.rs

@@ -135,6 +135,8 @@ pub enum IndexSummary {
     Offline(Summary),
     /// From a newer schema version and is likely incomplete or inaccurate
     Unsupported(Summary, u32),
+    /// An error was encountered despite being a supported schema version
+    Invalid(Summary),
 }
 
 impl IndexSummary {
@@ -144,7 +146,8 @@ impl IndexSummary {
             IndexSummary::Candidate(sum)
             | IndexSummary::Yanked(sum)
             | IndexSummary::Offline(sum)
-            | IndexSummary::Unsupported(sum, _) => sum,
+            | IndexSummary::Unsupported(sum, _)
+            | IndexSummary::Invalid(sum) => sum,
         }
     }
 
@@ -154,7 +157,8 @@ impl IndexSummary {
             IndexSummary::Candidate(sum)
             | IndexSummary::Yanked(sum)
             | IndexSummary::Offline(sum)
-            | IndexSummary::Unsupported(sum, _) => sum,
+            | IndexSummary::Unsupported(sum, _)
+            | IndexSummary::Invalid(sum) => sum,
         }
     }
 
@@ -164,6 +168,7 @@ impl IndexSummary {
             IndexSummary::Yanked(s) => IndexSummary::Yanked(f(s)),
             IndexSummary::Offline(s) => IndexSummary::Offline(f(s)),
             IndexSummary::Unsupported(s, v) => IndexSummary::Unsupported(f(s), v.clone()),
+            IndexSummary::Invalid(s) => IndexSummary::Invalid(f(s)),
         }
     }
 
@@ -282,6 +287,22 @@ impl IndexPackage<'_> {
     }
 }
 
+#[derive(Deserialize, Serialize)]
+struct IndexPackageMinimum {
+    name: InternedString,
+    vers: Version,
+}
+
+#[derive(Deserialize, Serialize, Default)]
+struct IndexPackageRustVersion {
+    rust_version: Option<RustVersion>,
+}
+
+#[derive(Deserialize, Serialize, Default)]
+struct IndexPackageV {
+    v: Option<u32>,
+}
+
 /// A dependency as encoded in the [`IndexPackage`] index JSON.
 #[derive(Deserialize, Serialize, Clone)]
 pub struct RegistryDependency<'a> {
@@ -729,10 +750,45 @@ impl IndexSummary {
         // between different versions that understand the index differently.
         // Make sure to consider the INDEX_V_MAX and CURRENT_CACHE_VERSION
         // values carefully when making changes here.
-        let index: IndexPackage<'_> = serde_json::from_slice(line)?;
+        let index_summary = (|| {
+            let index = serde_json::from_slice::<IndexPackage<'_>>(line)?;
+            let summary = index.to_summary(source_id)?;
+            Ok((index, summary))
+        })();
+        let (index, summary, valid) = match index_summary {
+            Ok((index, summary)) => (index, summary, true),
+            Err(err) => {
+                let Ok(IndexPackageMinimum { name, vers }) =
+                    serde_json::from_slice::<IndexPackageMinimum>(line)
+                else {
+                    // If we can't recover, prefer the original error
+                    return Err(err);
+                };
+                tracing::info!(
+                    "recoverying from failed parse of registry package {name}@{vers}: {err}"
+                );
+                let IndexPackageRustVersion { rust_version } =
+                    serde_json::from_slice::<IndexPackageRustVersion>(line).unwrap_or_default();
+                let IndexPackageV { v } =
+                    serde_json::from_slice::<IndexPackageV>(line).unwrap_or_default();
+                let index = IndexPackage {
+                    name,
+                    vers,
+                    rust_version,
+                    v,
+                    deps: Default::default(),
+                    features: Default::default(),
+                    features2: Default::default(),
+                    cksum: Default::default(),
+                    yanked: Default::default(),
+                    links: Default::default(),
+                };
+                let summary = index.to_summary(source_id)?;
+                (index, summary, false)
+            }
+        };
         let v = index.v.unwrap_or(1);
         tracing::trace!("json parsed registry {}/{}", index.name, index.vers);
-        let summary = index.to_summary(source_id)?;
 
         let v_max = if bindeps {
             INDEX_V_MAX + 1
@@ -742,6 +798,8 @@ impl IndexSummary {
 
         if v_max < v {
             Ok(IndexSummary::Unsupported(summary, v))
+        } else if !valid {
+            Ok(IndexSummary::Invalid(summary))
         } else if index.yanked.unwrap_or(false) {
             Ok(IndexSummary::Yanked(summary))
         } else {

src/cargo/sources/registry/mod.rs

@@ -834,6 +834,9 @@ impl<'gctx> Source for RegistrySource<'gctx> {
                                 summary.version()
                             );
                         }
+                        IndexSummary::Invalid(summary) => {
+                            tracing::debug!("invalid ({} {})", summary.name(), summary.version());
+                        }
                         IndexSummary::Offline(summary) => {
                             tracing::debug!("offline ({} {})", summary.name(), summary.version());
                         }

tests/testsuite/registry.rs

@@ -3012,10 +3012,13 @@ fn invalid_json_lines_error() {
         .with_stderr_data(str![[r#"
 [UPDATING] `dummy-registry` index
 [ERROR] failed to select a version for the requirement `foo = "^0.1.1"`
-candidate versions found which didn't match: 0.2.0, 0.1.0
+  version 0.1.3 requires cargo 1.2345
+  version 0.1.4 requires a Cargo version that supports index version 1000000000
+  version 0.1.5's index entry is invalid
+  version 0.1.6 requires a Cargo version that supports index version 1000000000
+  version 0.1.7's index entry is invalid
 location searched: `dummy-registry` index (which is replacing registry `crates-io`)
 required by package `a v0.5.0 ([ROOT]/foo)`
-perhaps a crate was updated and forgotten to be re-vendored?
 
 "#]])
         .run();
@@ -3024,10 +3027,13 @@ perhaps a crate was updated and forgotten to be re-vendored?
         .with_stderr_data(str![[r#"
 [UPDATING] `dummy-registry` index
 [ERROR] failed to select a version for the requirement `foo = "^0.1.1"`
-candidate versions found which didn't match: 0.2.0, 0.1.0
+  version 0.1.3 requires cargo 1.2345
+  version 0.1.4 requires a Cargo version that supports index version 1000000000
+  version 0.1.5's index entry is invalid
+  version 0.1.6 requires a Cargo version that supports index version 1000000000
+  version 0.1.7's index entry is invalid
 location searched: `dummy-registry` index (which is replacing registry `crates-io`)
 required by package `a v0.5.0 ([ROOT]/foo)`
-perhaps a crate was updated and forgotten to be re-vendored?
 
 "#]])
         .run();