Add a lint check for generated code

.github/workflows/ci.yaml

@@ -37,7 +37,9 @@ jobs:
       with:
         go-version-file: go.mod
         cache: false # for this job we rely on golangci-lint-action's cache
-    - name: Lint
+    - name: Lint (other)
+      run: script/lint
+    - name: Lint (golangci-lint)
       uses: golangci/golangci-lint-action@v3
       with:
         version: v1.52

script/lint

@@ -2,7 +2,18 @@
 
 set -eu
 
+: "${GITHUB_ACTIONS:=}"
+
 cd "$(dirname "$0")"
 cd ..
 
-exec go run github.com/golangci/golangci-lint/cmd/golangci-lint run
+go generate ./...
+if ! git diff --exit-code >/dev/null; then
+  echo "Error: generated code is not up-to-date! Run 'go generate ./...' and update your branch." >&2
+  exit 1
+fi
+
+# On GitHub actions, this is run as a separate task
+if [ "$GITHUB_ACTIONS" != "true" ]; then
+  exec go run github.com/golangci/golangci-lint/cmd/golangci-lint run
+fi

telemetry/tracestate.go

@@ -26,7 +26,7 @@ const (
 // Don't forget to rerun `go generate ./...` if you add or remove values from
 // the DetailLevel or SampleMode enums.
 //
-//go:generate stringer -type=DetailLevel,SampleMode -output=tracestate_string.go
+//go:generate go run golang.org/x/tools/cmd/stringer -type=DetailLevel,SampleMode -output=tracestate_string.go
 type DetailLevel int
 type SampleMode int