Add support for r.PathValue when built for Go 1.22.

route.go

@@ -232,6 +232,9 @@ func (router Router) getHandler(r *http.Request) http.Handler {
 	r.Header.Set("Trout-Pattern", route.pattern)
 	for key, vals := range route.params {
 		r.Header[http.CanonicalHeaderKey("Trout-Param-"+key)] = vals
+		for _, val := range vals {
+			setBuiltinRequestPathVar(r, key, val)
+		}
 	}
 
 	// if no handler is set, it could be because there's no handler for

route_below_go1_22.go

@@ -0,0 +1,8 @@
+//go:build !go1.22
+
+package trout
+
+import "net/http"
+
+func setBuiltinRequestPathVar(_ *http.Request, _, _ string) {
+}

route_go1_22.go

@@ -0,0 +1,9 @@
+//go:build go1.22
+
+package trout
+
+import "net/http"
+
+func setBuiltinRequestPathVar(r *http.Request, name, value string) {
+	r.SetPathValue(name, value)
+}

route_go1_22_examples_test.go

@@ -0,0 +1,31 @@
+//go:build go1.22
+
+package trout_test
+
+import (
+	"net/http"
+
+	"darlinggo.co/trout/v2"
+)
+
+func ExampleRouter_Endpoint_pathValues() {
+	postsHandler := http.HandlerFunc(
+		func(w http.ResponseWriter, r *http.Request) {
+			// we populate the PathValue request property introduced
+			// in Go 1.22 when you build with Go 1.22.
+			id := r.PathValue("id")
+			_, err := w.Write([]byte(id))
+			if err != nil {
+				panic(err)
+			}
+		})
+
+	var router trout.Router
+	router.Endpoint("/posts/{id}").Handler(postsHandler)
+
+	req, _ := http.NewRequest("GET", "http://example.com/posts/foo", nil)
+	router.ServeHTTP(exampleResponseWriter{}, req)
+
+	// Output:
+	// foo
+}