[src][out][opt_args] fix order of reports with colliding locations

When reporting on optional arguments, the different values are sorted by
`abspath` and locations first. When 2 files have the same filename
(found in locations), their `abspath` would be identical too because it
only provides the path of the latest of the 2 files met. Thus, they were
reported together although they belong to different directories.
Using the available builddirs to reconstruct the filepaths instead of
abspath is less error-prone and fixes the ordering issue. Howver, it
incurs the cost of the new strings.

Author: fantazio

check/threshold-3-0.5/threshold-3-0.5.ref

@@ -858,11 +858,10 @@ Nothing else to report in this section
 ./examples/using_make/dir/anonFn2.mli:2: ?a   (2/3 calls)
 ./examples/using_make/dir/anonFn2.mli:2: ?b   (2/3 calls)
 ./examples/using_make/dir/match_opt.ml:1: ?b   (2/3 calls)
-./examples/using_make/dir/matchopt.ml:1: ?x   (3/4 calls): Not detected
+./examples/using_make/dir/matchopt.ml:1: ?x   (3/4 calls)
 ./examples/using_make/dir/ref_fn.ml:1: ?a   (2/3 calls)
 ./examples/using_make/dir/ref_fn.ml:1: ?b   (2/3 calls)
 
-./examples/using_make/dir/matchopt.ml:1: ?x   (3/4 calls): Should not be detected
 ./examples/using_make/matchopt.ml:1: ?x   (3/4 calls)
 
 ./examples/using_make/opt/sig_struct.ml:2: ?x   (2/3 calls)
@@ -1037,12 +1036,10 @@ Nothing else to report in this section
 ./examples/using_make/dir/anonFn.mli:3: ?a   (1/2 calls)
 ./examples/using_make/dir/anonFn.mli:3: ?b   (1/2 calls)
 ./examples/using_make/dir/anonFn2.mli:1: ?b   (2/3 calls)
-./examples/using_make/dir/matchopt.ml:1: ?y   (3/4 calls): Not detected
-./examples/using_make/dir/matchopt.ml:1: ?z   (3/4 calls): Not detected
+./examples/using_make/dir/matchopt.ml:1: ?y   (3/4 calls)
+./examples/using_make/dir/matchopt.ml:1: ?z   (3/4 calls)
 ./examples/using_make/let_in.ml:1: ?b   (2/3 calls)
-./examples/using_make/dir/matchopt.ml:1: ?y   (3/4 calls): Should not be detected
 ./examples/using_make/matchopt.ml:1: ?y   (3/4 calls)
-./examples/using_make/dir/matchopt.ml:1: ?z   (3/4 calls): Should not be detected
 ./examples/using_make/matchopt.ml:1: ?z   (3/4 calls)
 ./examples/using_make/opt_in_opt.ml:1: ?b   (1/2 calls)
 --------
@@ -1091,7 +1088,7 @@ Nothing else to report in this section
 --------------------------------------------------------------------------------
 
 
-Total: 926
-Success: 920
-Failed: 6
-Ratio: 99.3520518359%
+Total: 923
+Success: 923
+Failed: 0
+Ratio: 100.%

src/deadCode.ml

@@ -554,8 +554,10 @@ let report_opt_args s l =
           let ratio = float_of_int (List.length l) /. float_of_int total
           in (builddir, loc, lab, l, ratio, total))
         l
-      |> List.fast_sort (fun (_, loc1, lab1, slot1, _, _) (_, loc2, lab2, slot2, _, _) ->
-          compare (DeadCommon.abs loc1, loc1, lab1, slot1) (DeadCommon.abs loc2, loc2, lab2, slot2))
+      |> List.fast_sort (fun (builddir1, loc1, lab1, slot1, _, _) (builddir2, loc2, lab2, slot2, _, _) ->
+          let fn1 = Filename.concat builddir1 loc1.Lexing.pos_fname in
+          let fn2 = Filename.concat builddir2 loc2.Lexing.pos_fname in
+          compare (fn1, loc1, lab1, slot1) (fn2, loc2, lab2, slot2))
     in
 
     let change =