From 894158339eed4ac779b1ba761bf393b4a4319731 Mon Sep 17 00:00:00 2001
From: Shon Feder <shon.feder@gmail.com>
Date: Sun, 25 May 2025 21:36:09 -0400
Subject: [PATCH] Update to support cohttp 6

Preparation for Cohttp 6 started in
2022 (https://github.com/mirage/ocaml-cohttp/blob/main/CHANGES.md#v600alpha0-2022-10-24)
and 6 has been stable and released since Nov of 2024.
See https://github.com/mirage/ocaml-cohttp/blob/main/CHANGES.md#v600-2024-11-21

Removal of the `open Cohttp_lwt` solves deprecation warnings issued by
Cohttp 6, since everything we were using from the open has been moved
into `Cohttp`.
---
 dune-project                                       |  4 +---
 opentelemetry-cohttp-lwt.opam                      |  2 +-
 .../cohttp/opentelemetry_cohttp_lwt.ml             | 14 +++++++++++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/dune-project b/dune-project
index 60b778fd..ec273074 100644
--- a/dune-project
+++ b/dune-project
@@ -101,9 +101,7 @@
   (lwt
    (>= "5.3"))
   (cohttp-lwt
-   (and
-    (>= "4.0.0")
-    (< "6")))
+   (>= "6.0.0"))
   (alcotest :with-test))
  (synopsis "Opentelemetry tracing for Cohttp HTTP servers"))
 
diff --git a/opentelemetry-cohttp-lwt.opam b/opentelemetry-cohttp-lwt.opam
index 4d3fd0da..ad66a0ef 100644
--- a/opentelemetry-cohttp-lwt.opam
+++ b/opentelemetry-cohttp-lwt.opam
@@ -18,7 +18,7 @@ depends: [
   "opentelemetry-lwt" {= version}
   "odoc" {with-doc}
   "lwt" {>= "5.3"}
-  "cohttp-lwt" {>= "4.0.0" & < "6"}
+  "cohttp-lwt" {>= "6.0.0"}
   "alcotest" {with-test}
 ]
 build: [
diff --git a/src/integrations/cohttp/opentelemetry_cohttp_lwt.ml b/src/integrations/cohttp/opentelemetry_cohttp_lwt.ml
index fd2ff1a4..67272d36 100644
--- a/src/integrations/cohttp/opentelemetry_cohttp_lwt.ml
+++ b/src/integrations/cohttp/opentelemetry_cohttp_lwt.ml
@@ -1,7 +1,6 @@
 module Otel = Opentelemetry
 module Otel_lwt = Opentelemetry_lwt
 open Cohttp
-open Cohttp_lwt
 
 module Server : sig
   val trace :
@@ -144,6 +143,17 @@ let client ?(scope : Otel.Scope.t option) (module C : Cohttp_lwt.S.Client) =
   let module Traced = struct
     open Lwt.Syntax
 
+    (*   These types and values are not customized by our client, but are required to satisfy
+         [Cohttp_lwt.S.Client]. *)
+    include (C : sig
+               type ctx = C.ctx
+               type 'a io = 'a C.io
+               type 'a with_context = 'a C.with_context
+               type body = C.body
+               val map_context : 'a with_context -> ('a -> 'b) -> 'b with_context
+               val set_cache : Cohttp_lwt.S.call -> unit
+             end)
+
     let attrs_for ~uri ~meth:_ () =
       [
         "http.method", `String (Code.string_of_method `GET);
@@ -175,8 +185,6 @@ let client ?(scope : Otel.Scope.t option) (module C : Cohttp_lwt.S.Client) =
         (Traceparent.to_value ~trace_id:scope.trace_id ~parent_id:scope.span_id
            ())
 
-    type ctx = C.ctx
-
     let call ?ctx ?headers ?body ?chunked meth (uri : Uri.t) :
         (Response.t * Cohttp_lwt.Body.t) Lwt.t =
       let trace_id, parent, attrs = context_for ~uri ~meth in