Fix a bug in the interpretation of META files

Before this commit, when there was more than one applicable
assignment, the one with the lowest number of formal predicates was
selected instead of the one with the biggest number of formal predicates

CHANGES.org

@@ -10,6 +10,11 @@
   without =ppx_driver.runner= (#37). These problem should go away soon
   when we start using =--cookie=
 
+- Fix the interpretation of META files when there is more than one
+  applicable assignment. Before this fix, the one with the lowest
+  number of formal predicates was selected instead of the one with the
+  biggest number of formal predicates
+
 * 1.0+beta5 (22/03/2017)
 
 - When =ocamlfind= is present in the =PATH=, do not attempt to call

src/findlib.ml

@@ -70,9 +70,9 @@ end
 
 (* Set of rules for a given variable of a package *)
 module Rules = struct
-  (* To implement the algorithm described in [1], [set_rules] is sorted by number of format
-     predicates, then according to the order of the META file. [add_rules] are in the same
-     order as in the META file.
+  (* To implement the algorithm described in [1], [set_rules] is sorted by decreasing
+     number of formal predicates, then according to the order of the META
+     file. [add_rules] are in the same order as in the META file.
 
      [1] http://projects.camlcity.org/projects/dl/findlib-1.6.3/doc/ref-html/r729.html *)
   type t =
@@ -101,7 +101,7 @@ module Rules = struct
     let set_rules =
       List.map rules.set_rules ~f:Rule.make
       |> List.stable_sort ~cmp:(fun a b ->
-        compare (Rule.formal_predicates_count a) (Rule.formal_predicates_count b))
+        compare (Rule.formal_predicates_count b) (Rule.formal_predicates_count a))
     in
     { add_rules; set_rules }
 end

test/expect-tests/expect_test.mll

@@ -107,7 +107,7 @@ let main () =
 
   let corrected_fn = fn ^ ".corrected" in
   (* Temporary hack: *)
-  Sys.chdir "../..";
+  (* Sys.chdir "../.."; *)
   if txt <> res then begin
     let oc = open_out_bin corrected_fn in
     output_string oc res;

test/expect-tests/tests.mlt

@@ -3,6 +3,7 @@
 #warnings "-40";;
 
 open Jbuilder
+open Import
 
 let print_pkg ppf pkg =
   Format.fprintf ppf "<package:%s>" pkg.Findlib.name
@@ -35,5 +36,26 @@ val pkg : Jbuilder.Findlib.package = <package:foo>
 pkg.requires;;
 
 [%%expect{|
-- : Jbuilder.Findlib.package list = [<package:bar>]
+- : Jbuilder.Findlib.package list = [<package:baz>]
+|}]
+
+(* +-----------------------------------------------------------------+
+   | Meta parsing/simplification                                     |
+   +-----------------------------------------------------------------+ *)
+
+open Meta
+
+let meta =
+  { name = "foo"
+  ; entries = Meta.load "test/expect-tests/findlib-db/foo/META"
+  }
+
+[%%expect{|
+val meta : Jbuilder.Meta.t =
+  {name = "foo";
+   entries =
+    [Rule {var = "requires"; predicates = []; action = Set; value = "bar"};
+     Rule
+      {var = "requires"; predicates = [Pos "ppx_driver"]; action = Set;
+       value = "baz"}]}
 |}]