From e186bf4e7ae23a15446f22b77ff9f5c96469f8a8 Mon Sep 17 00:00:00 2001
From: Weihang Lo <me@weihanglo.tw>
Date: Tue, 26 Mar 2024 16:52:24 -0400
Subject: [PATCH 1/3] test(generate-lockfile): verify `--offline` panics

---
 tests/testsuite/generate_lockfile.rs | 38 ++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/tests/testsuite/generate_lockfile.rs b/tests/testsuite/generate_lockfile.rs
index 0a3e1395a58..aa4aed1980a 100644
--- a/tests/testsuite/generate_lockfile.rs
+++ b/tests/testsuite/generate_lockfile.rs
@@ -237,3 +237,41 @@ fn duplicate_entries_in_lockfile() {
         )
         .run();
 }
+
+#[cargo_test]
+fn generate_lockfile_holds_lock_and_offline() {
+    Package::new("syn", "1.0.0").publish();
+
+    let p = project()
+        .file(
+            "Cargo.toml",
+            r#"
+                [package]
+                name = "foo"
+
+                [dependencies]
+                syn = "1.0"
+            "#,
+        )
+        .file("src/lib.rs", "")
+        .build();
+
+    p.cargo("generate-lockfile")
+        .with_stderr(
+            "\
+[UPDATING] `[..]` index
+[LOCKING] 2 packages
+",
+        )
+        .run();
+
+    p.cargo("generate-lockfile --offline")
+        .with_status(101)
+        .with_stderr_contains(
+            "\
+[..]thread 'main' panicked[..]
+[..]package cache lock is not currently held[..]
+",
+        )
+        .run();
+}

From 5587af7caf1f4e96a56c6dc35b13f84c99987f20 Mon Sep 17 00:00:00 2001
From: Weihang Lo <me@weihanglo.tw>
Date: Tue, 26 Mar 2024 16:20:19 -0400
Subject: [PATCH 2/3] refactor: remove unnecessary export so no need to deal
 with lock acquisitions

---
 src/cargo/ops/cargo_generate_lockfile.rs | 2 +-
 src/cargo/ops/mod.rs                     | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/cargo/ops/cargo_generate_lockfile.rs b/src/cargo/ops/cargo_generate_lockfile.rs
index 87aa7242395..d6fdc3d94a0 100644
--- a/src/cargo/ops/cargo_generate_lockfile.rs
+++ b/src/cargo/ops/cargo_generate_lockfile.rs
@@ -331,7 +331,7 @@ fn print_lockfile_sync(
     Ok(())
 }
 
-pub fn print_lockfile_updates(
+fn print_lockfile_updates(
     gctx: &GlobalContext,
     previous_resolve: &Resolve,
     resolve: &Resolve,
diff --git a/src/cargo/ops/mod.rs b/src/cargo/ops/mod.rs
index 9a751793da2..3b4c74c8922 100644
--- a/src/cargo/ops/mod.rs
+++ b/src/cargo/ops/mod.rs
@@ -9,7 +9,6 @@ pub use self::cargo_doc::{doc, DocOptions, OutputFormat};
 pub use self::cargo_fetch::{fetch, FetchOptions};
 pub use self::cargo_generate_lockfile::generate_lockfile;
 pub use self::cargo_generate_lockfile::print_lockfile_changes;
-pub use self::cargo_generate_lockfile::print_lockfile_updates;
 pub use self::cargo_generate_lockfile::update_lockfile;
 pub use self::cargo_generate_lockfile::UpdateOptions;
 pub use self::cargo_install::{install, install_list};

From f1c139624f0fe85fdf34e43919e3c9d506bca3f7 Mon Sep 17 00:00:00 2001
From: Weihang Lo <me@weihanglo.tw>
Date: Tue, 26 Mar 2024 16:53:45 -0400
Subject: [PATCH 3/3] fix(generate-lockfile): hold lock before querying index

---
 src/cargo/ops/cargo_generate_lockfile.rs | 5 +++++
 src/cargo/ops/resolve.rs                 | 5 -----
 tests/testsuite/generate_lockfile.rs     | 4 +---
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/cargo/ops/cargo_generate_lockfile.rs b/src/cargo/ops/cargo_generate_lockfile.rs
index d6fdc3d94a0..e303d868da4 100644
--- a/src/cargo/ops/cargo_generate_lockfile.rs
+++ b/src/cargo/ops/cargo_generate_lockfile.rs
@@ -166,12 +166,17 @@ pub fn update_lockfile(ws: &Workspace<'_>, opts: &UpdateOptions<'_>) -> CargoRes
     Ok(())
 }
 
+/// Prints lockfile change statuses.
+///
+/// This would acquire the package-cache lock, as it may update the index to
+/// show users latest available versions.
 pub fn print_lockfile_changes(
     gctx: &GlobalContext,
     previous_resolve: Option<&Resolve>,
     resolve: &Resolve,
     registry: &mut PackageRegistry<'_>,
 ) -> CargoResult<()> {
+    let _lock = gctx.acquire_package_cache_lock(CacheLockMode::DownloadExclusive)?;
     if let Some(previous_resolve) = previous_resolve {
         print_lockfile_sync(gctx, previous_resolve, resolve, registry)
     } else {
diff --git a/src/cargo/ops/resolve.rs b/src/cargo/ops/resolve.rs
index 1042c897bcf..31a37551414 100644
--- a/src/cargo/ops/resolve.rs
+++ b/src/cargo/ops/resolve.rs
@@ -256,11 +256,6 @@ fn resolve_with_registry<'gctx>(
         false
     };
     if print {
-        // We only want one Cargo at a time resolving a crate graph since this can
-        // involve a lot of frobbing of the global caches.
-        let _lock = ws
-            .gctx()
-            .acquire_package_cache_lock(CacheLockMode::DownloadExclusive)?;
         ops::print_lockfile_changes(ws.gctx(), prev.as_ref(), &resolve, registry)?;
     }
     Ok(resolve)
diff --git a/tests/testsuite/generate_lockfile.rs b/tests/testsuite/generate_lockfile.rs
index aa4aed1980a..2c0b65a0db1 100644
--- a/tests/testsuite/generate_lockfile.rs
+++ b/tests/testsuite/generate_lockfile.rs
@@ -266,11 +266,9 @@ fn generate_lockfile_holds_lock_and_offline() {
         .run();
 
     p.cargo("generate-lockfile --offline")
-        .with_status(101)
         .with_stderr_contains(
             "\
-[..]thread 'main' panicked[..]
-[..]package cache lock is not currently held[..]
+[LOCKING] 2 packages
 ",
         )
         .run();