--- /dev/null
+package pkg
+
+import "net/http"
+
+func fn() {
+ var r http.Request
+ h := http.Header{}
+ var m map[string][]string
+ _ = h["foo"] // want `keys in http\.Header are canonicalized`
+ h["foo"] = nil
+ _ = r.Header["foo"] // want `keys in http\.Header are canonicalized`
+ r.Header["foo"] = nil
+ _ = m["foo"]
+}