6893: "tag not used" warning when using (p)dep to declare linking tags

git-svn-id: http://caml.inria.fr/svn/ocaml/version/4.02@16162 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

Author: Damien Doligez

Changes

@@ -208,6 +208,8 @@ Bug fixes:
   (Jacques Garrigue, report by Valentin Gatien-Baron)
 - PR#6889: ast_mapper fails to rewrite class attributes
   (Sébastien Briais)
+- PR#6893: ocamlbuild:  "tag not used" warning when using (p)dep
+  (Gabriel Scherer, report by Christiano Haesbaert)
 - GPR#143: fix getsockopt behaviour for boolean socket options
   (Anil Madhavapeddy and Andrew Ray)
 - GPR#190: typo in pervasives

ocamlbuild/command.ml

@@ -393,6 +393,9 @@ let pdep tags ptag deps =
   Param_tags.declare ptag
     (fun param -> dep (Param_tags.make ptag param :: tags) (deps param))
 
+let list_all_deps () =
+  !all_deps_of_tags
+
 (*
 let to_string_for_digest x =
   let rec cmd_of_spec =

ocamlbuild/command.mli

@@ -46,4 +46,6 @@ val dep : Tags.elt list -> pathname list -> unit
 
 val pdep : Tags.elt list -> Tags.elt -> (string -> pathname list) -> unit
 
+val list_all_deps : unit -> (Tags.t * pathname list) list
+
 val file_or_exe_exists: string -> bool

ocamlbuild/configuration.ml

@@ -81,10 +81,11 @@ let tag_any tags =
 let check_tags_usage useful_tags =
   let check_tag (tag, loc) =
     if not (Tags.mem tag useful_tags) then
-      Log.eprintf "%aWarning: the tag %S is not used in any flag declaration, \
-                   so it will have no effect; it may be a typo. Otherwise use \
-                   `mark_tag_used` in your myocamlbuild.ml to disable \
-                   this warning."
+
+      Log.eprintf "%aWarning: the tag %S is not used in any flag or dependency \
+                   declaration, so it will have no effect; it may be a typo. \
+                   Otherwise you can use `mark_tag_used` in your myocamlbuild.ml \
+                   to disable this warning."
         Loc.print_loc loc tag
   in
   let check_conf (_, values) =

ocamlbuild/main.ml

@@ -205,7 +205,14 @@ let proceed () =
     raise Exit_silently
   end;
 
-  let all_tags = Tags.union builtin_useful_tags (Flags.get_used_tags ()) in
+  let all_tags =
+    let builtin = builtin_useful_tags in
+    let used_in_flags = Flags.get_used_tags () in
+    let used_in_deps =
+      List.fold_left (fun acc (tags, _deps) -> Tags.union acc tags)
+        Tags.empty (Command.list_all_deps ())
+    in
+    Tags.union builtin (Tags.union used_in_flags used_in_deps) in
   Configuration.check_tags_usage all_tags;
 
   Digest_cache.init ();