[ci] Roll pinned nightly toolchain (#2557)

gherrit-pr-id: I0da5e9161750390c5573fa4f299f50469951740b

Author: google-pr-creation-bot

Cargo.toml

@@ -60,7 +60,7 @@ zerocopy-panic-in-const-and-vec-try-reserve-1-57-0 = "1.57.0"
 [package.metadata.ci]
 # The versions of the stable and nightly compiler toolchains to use in CI.
 pinned-stable = "1.87.0"
-pinned-nightly = "nightly-2025-05-28"
+pinned-nightly = "nightly-2025-05-29"
 
 [package.metadata.docs.rs]
 all-features = true

build.rs

@@ -70,11 +70,19 @@ fn main() {
     let rustc_version = rustc_version();
 
     if rustc_version >= (Version { major: 1, minor: 77, patch: 0 }) {
-        // This tells the `unexpected_cfgs` lint to expect to see all of these
-        // `cfg`s. The `cargo::` syntax was only added in 1.77, so we don't emit
-        // these on earlier toolchain versions.
         for version_cfg in &version_cfgs {
+            // This tells the `unexpected_cfgs` lint to expect to see all of
+            // these `cfg`s. The `cargo::` syntax was only added in 1.77, so we
+            // don't emit these on earlier toolchain versions.
             println!("cargo:rustc-check-cfg=cfg({})", version_cfg.cfg_name);
+
+            // This tells the `unexpected_cfgs` lint to expect to see `cfg`s of
+            // the form `rust = "1.2.3"`. These aren't real `cfg`s, but we use
+            // them in `cfg_attr(doc_cfg, doc(cfg(rust = "1.2.3")))` on items
+            // that are version-gated so that the rendered Rustdoc shows which
+            // Rust toolchain versions those items are available on.
+            let Version { major, minor, patch } = version_cfg.version;
+            println!("cargo:rustc-check-cfg=cfg(rust, values(\"{}.{}.{}\"))", major, minor, patch);
         }
         // FIXME(https://github.com/rust-lang/rust/issues/124816): Remove these
         // once they're no longer needed.

testutil/Cargo.toml

@@ -16,10 +16,16 @@ cargo_metadata = "0.18.0"
 # Pin to 0.1.5 because more recent versions require a Rust version more recent
 # than our MSRV.
 cargo-platform = "=0.1.5"
+# Pin to 0.4.11 because more recent versions require a Rust version more recent
+# than our MSRV.
+lock_api = "=0.4.11"
 # Pin to 2.5.0 because more recent versions require a Rust version more recent
 # than our MSRV.
 memchr = "=2.5.0"
 parking_lot = "=0.12.1"
+# Pin to 0.9.10 because more recent versions require a Rust version more recent
+# than our MSRV.
+parking_lot_core = "=0.9.10"
 rustc_version = "0.4.0"
 # Pin to 0.3.0 because more recent versions require a Rust version more recent
 # than our MSRV.