From a87c3f20e846c00e53d695497dba7038edbd12f0 Mon Sep 17 00:00:00 2001
From: Valentin Lorentz <progval@progval.net>
Date: Thu, 13 Aug 2015 11:59:04 +0200
Subject: [PATCH] Enable ocamldoc to build reproducible manpages

Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=794586
Signed-off-by: Stephane Glondu <steph@glondu.net>
---
 ocamldoc/odoc_man.ml   | 15 +++++----------
 ocamldoc/odoc_misc.ml  | 12 ++++++++++--
 ocamldoc/odoc_misc.mli |  7 ++++++-
 3 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/ocamldoc/odoc_man.ml b/ocamldoc/odoc_man.ml
index 615c5e172..3c85aa32a 100644
--- a/ocamldoc/odoc_man.ml
+++ b/ocamldoc/odoc_man.ml
@@ -864,14 +864,13 @@ class man =
     (** Generate the man page for the given class.*)
     method generate_for_class cl =
       Odoc_info.reset_type_names () ;
-      let date = Unix.time () in
       let file = self#file_name cl.cl_name in
       try
         let chanout = self#open_out file in
         let b = new_buf () in
         bs b (".TH \""^cl.cl_name^"\" ");
         bs b !man_section ;
-        bs b (" "^(Odoc_misc.string_of_date ~hour: false date)^" ");
+        bs b (" source: "^Odoc_misc.current_date^" ");
         bs b "OCamldoc ";
         bs b ("\""^(match !Global.title with Some t -> t | None -> "")^"\"\n");
 
@@ -923,14 +922,13 @@ class man =
     (** Generate the man page for the given class type.*)
     method generate_for_class_type ct =
       Odoc_info.reset_type_names () ;
-      let date = Unix.time () in
       let file = self#file_name ct.clt_name in
       try
         let chanout = self#open_out file in
         let b = new_buf () in
         bs b (".TH \""^ct.clt_name^"\" ");
         bs b !man_section ;
-        bs b (" "^(Odoc_misc.string_of_date ~hour: false date)^" ");
+        bs b (" source: "^Odoc_misc.current_date^" ");
         bs b "OCamldoc ";
         bs b ("\""^(match !Global.title with Some t -> t | None -> "")^"\"\n");
 
@@ -1016,14 +1014,13 @@ class man =
     (** Generate the man file for the given module type.
        @raise Failure if an error occurs.*)
     method generate_for_module_type mt =
-      let date = Unix.time () in
       let file = self#file_name mt.mt_name in
       try
         let chanout = self#open_out file in
         let b = new_buf () in
         bs b (".TH \""^mt.mt_name^"\" ");
         bs b !man_section ;
-        bs b (" "^(Odoc_misc.string_of_date ~hour: false date)^" ");
+        bs b (" source: "^Odoc_misc.current_date^" ");
         bs b "OCamldoc ";
         bs b ("\""^(match !Global.title with Some t -> t | None -> "")^"\"\n");
 
@@ -1099,14 +1096,13 @@ class man =
     (** Generate the man file for the given module.
        @raise Failure if an error occurs.*)
     method generate_for_module m =
-      let date = Unix.time () in
       let file = self#file_name m.m_name in
       try
         let chanout = self#open_out file in
         let b = new_buf () in
         bs b (".TH \""^m.m_name^"\" ");
         bs b !man_section ;
-        bs b (" "^(Odoc_misc.string_of_date ~hour: false date)^" ");
+        bs b (" source: "^Odoc_misc.current_date^" ");
         bs b "OCamldoc ";
         bs b ("\""^(match !Global.title with Some t -> t | None -> "")^"\"\n");
 
@@ -1206,14 +1202,13 @@ class man =
           | Res_const (_,f) -> f.vc_name
          )
      in
-     let date = Unix.time () in
       let file = self#file_name name in
       try
         let chanout = self#open_out file in
         let b = new_buf () in
         bs b (".TH \""^name^"\" ");
         bs b !man_section ;
-        bs b (" "^(Odoc_misc.string_of_date ~hour: false date)^" ");
+        bs b (" source: "^Odoc_misc.current_date^" ");
         bs b "OCamldoc ";
         bs b ("\""^(match !Global.title with Some t -> t | None -> "")^"\"\n");
         bs b ".SH NAME\n";
diff --git a/ocamldoc/odoc_misc.ml b/ocamldoc/odoc_misc.ml
index 4c74476da..456225f62 100644
--- a/ocamldoc/odoc_misc.ml
+++ b/ocamldoc/odoc_misc.ml
@@ -223,9 +223,9 @@ let apply_opt f v_opt =
     None -> None
   | Some v -> Some (f v)
 
-let string_of_date ?(hour=true) d =
+let string_of_date ?(absolute=false) ?(hour=true) d =
   let add_0 s = if String.length s < 2 then "0"^s else s in
-  let t = Unix.localtime d in
+  let t = (if absolute then Unix.gmtime else Unix.localtime) d in
   (string_of_int (t.Unix.tm_year + 1900))^"-"^
   (add_0 (string_of_int (t.Unix.tm_mon + 1)))^"-"^
   (add_0 (string_of_int t.Unix.tm_mday))^
@@ -238,6 +238,14 @@ let string_of_date ?(hour=true) d =
      ""
   )
 
+let current_date =
+  let time =
+    try
+      float_of_string (Sys.getenv "SOURCE_DATE_EPOCH")
+    with
+      Not_found -> Unix.time ()
+  in string_of_date ~absolute: true ~hour: false time
+
 
 let rec text_list_concat sep l =
   match l with
diff --git a/ocamldoc/odoc_misc.mli b/ocamldoc/odoc_misc.mli
index dd5a7fcb9..38ff0612b 100644
--- a/ocamldoc/odoc_misc.mli
+++ b/ocamldoc/odoc_misc.mli
@@ -62,7 +62,12 @@ val apply_opt : ('a -> 'b) -> 'a option -> 'b option
 
 (** Return a string representing a date given as a number of seconds
    since 1970. The hour is optionnaly displayed. *)
-val string_of_date : ?hour:bool -> float -> string
+val string_of_date : ?absolute:bool -> ?hour:bool -> float -> string
+
+(* Value returned by string_of_date for current time.
+ * Uses environment variable SOURCE_DATE_EPOCH if set; falls back to
+ * current timestamp otherwise. *)
+val current_date : string
 
 (** Return the first sentence (until the first dot) of a text.
    Don't stop in the middle of [Code], [Verbatim], [List], [Lnum],
-- 
2.17.1