chore(examples): Add tower feature back to make udeps happy (hyperium#2432)

Reference hyperium#2431

---------

Co-authored-by: Ivan Babrou <[email protected]>

Author: 2 people

examples/Cargo.toml

@@ -273,6 +273,7 @@ h2c = ["dep:hyper", "dep:tower", "dep:http", "dep:hyper-util"]
 cancellation = ["dep:tokio-util"]
 
 full = ["gcp", "routeguide", "reflection", "autoreload", "health", "grpc-web", "tracing", "uds", "streaming", "mock", "json-codec", "compression", "tls", "tls-rustls", "tls-client-auth", "types", "cancellation", "h2c"]
+tower = ["dep:tower", "dep:http"]
 default = ["full"]
 
 [dependencies]

flake.nix

@@ -100,6 +100,39 @@
               ${config.pre-commit.installationScript}
             '';
           };
+
+          # App for running the full CI udeps check
+          # `nix run .#udeps-ci`
+          apps.udeps-ci = {
+            type = "app";
+            program = "${pkgs.writeShellScript "udeps-ci" ''
+              set -e
+              export PATH="${pkgs.rustup}/bin:${pkgs.cargo-udeps}/bin:${pkgs.cargo-hack}/bin:$PATH"
+
+              # Ensure nightly toolchain is installed
+              if ! rustup toolchain list | grep -q "nightly-2025-03-27"; then
+                echo "Installing nightly-2025-03-27 toolchain..."
+                rustup toolchain install nightly-2025-03-27
+              fi
+
+              # Set the toolchain for this run
+              export RUSTUP_TOOLCHAIN=nightly-2025-03-27
+
+              echo "Running cargo hack udeps..."
+              cargo hack udeps --workspace --exclude-features=_tls-any,tls,tls-aws-lc,tls-ring,tls-connect-info --each-feature
+
+              echo "Running tonic TLS feature checks..."
+              cargo udeps --package tonic --features tls-ring,transport
+              cargo udeps --package tonic --features tls-ring,server
+              cargo udeps --package tonic --features tls-ring,channel
+              cargo udeps --package tonic --features tls-aws-lc,transport
+              cargo udeps --package tonic --features tls-aws-lc,server
+              cargo udeps --package tonic --features tls-aws-lc,channel
+              cargo udeps --package tonic --features tls-connect-info
+
+              echo "✓ All udeps checks passed!"
+            ''}";
+          };
         };
     };
 }

grpc/Cargo.toml

@@ -27,6 +27,9 @@ _runtime-tokio = [
     "dep:socket2",
     "dep:tower",
 ]
+# Used for testing with udeps as it wants this feature to exist
+# to be able to do its checks.
+tower = ["_runtime-tokio"]
 
 [dependencies]
 bytes = "1.10.1"