Specify build and source trees in ocamldep

Changes

@@ -156,6 +156,10 @@ Working version
   (Tim McGilchrist and Sebastien Hinderer, review by Sebastien Hinderer,
    Gabriel Scherer and Antonin Décimo)
 
+- #12239: Add -source-tree and -build-tree options to ocamldep to
+  specify where to find dependencies and where to output a target.
+  (Antonin Décimo, review by Sébastien Hinderer, Nicolás Ojeda Bär)
+
 ### Manual and documentation:
 
 - #13694: Fix name for caml_hash_variant in the C interface.

driver/makedepend.ml

@@ -34,6 +34,8 @@ let nocwd = ref false
 let one_line = ref false
 let allow_approximation = ref false
 let debug = ref false
+let source_tree = ref ""
+let build_tree = ref ""
 
 (* [(dir, contents)] where [contents] is returned by [Sys.readdir dir]. *)
 let load_path = ref ([] : (string * string array) list)
@@ -190,25 +192,44 @@ let print_filename s =
 
 let print_dependencies target_files deps =
   let pos = ref 0 in
-  let print_on_same_line item =
+  let artifacts = [".cmi"; ".cmo"; ".cmx"; ".cmxs"; ".o"] in
+  let print_prefix prefix =
+    match !prefix with
+    | "" -> Fun.id, 0
+    | prefix ->
+       let len = String.length prefix in
+       let dir_sep = if Sys.os_type <> "Windows" || !Clflags.force_slash then
+                       '/' else '\\' in
+       let s, len = if String.get prefix (len - 1) = dir_sep then
+                      prefix, len
+                    else prefix ^ String.make 1 dir_sep, len + 1 in
+       (fun () -> print_string s; pos := !pos + len), len
+  in
+  let print_build_tree, build_tree_len = print_prefix build_tree
+  and print_source_tree, _ = print_prefix source_tree
+  in
+  let print_on_same_line ~is_artifact item =
     if !pos <> 0 then print_string " ";
+    if is_artifact then print_build_tree ()
+    else print_source_tree ();
     print_filename item;
     pos := !pos + String.length item + 1;
-  in
-  let print_on_new_line item =
+  and print_on_new_line ~is_artifact item =
     print_string escaped_eol;
+    if is_artifact then print_build_tree ()
+    else print_source_tree ();
     print_filename item;
     pos := String.length item + 4;
   in
   let print_compact item =
-    if !one_line || (!pos + 1 + String.length item <= 77)
-    then print_on_same_line item
-    else print_on_new_line item
-  in
-  let print_dep item =
+    if !one_line || (!pos + 1 + build_tree_len + String.length item <= 77)
+    then print_on_same_line ~is_artifact:true item
+    else print_on_new_line ~is_artifact:true item
+  and print_dep item =
+    let is_artifact = List.mem (Filename.extension item) artifacts in
     if !one_line
-    then print_on_same_line item
-    else print_on_new_line item
+    then print_on_same_line ~is_artifact item
+    else print_on_new_line ~is_artifact item
   in
   List.iter print_compact target_files;
   print_string " "; print_string depends_on;
@@ -624,6 +645,10 @@ let run_main argv =
         " (Windows) Preserve any backslash \\ in file paths";
       "-sort", Arg.Set sort_files,
         " Sort files according to their dependencies";
+      "-build-tree", Arg.String(fun s -> build_tree := s),
+        "<path>  Tree where build artifacts are written";
+      "-source-tree", Arg.String(fun s -> source_tree := s),
+        "<path>  Tree where dependencies are found";
       "-version", Arg.Unit print_version,
         " Print version and exit";
       "-vnum", Arg.Unit print_version_num,

man/ocamldep.1

@@ -187,6 +187,12 @@ Under Unix, this option does nothing.
 .B \-sort
 Sort files according to their dependencies.
 .TP
+.B \-build\-tree \ path
+Tree where build artifacts are written.
+.TP
+.B \-source\-tree \ path
+Tree where dependencies are found.
+.TP
 .B \-version
 Print version string and exit.
 .TP

manual/src/cmds/ocamldep.etex

@@ -138,6 +138,12 @@ nothing.
 \item["-sort"]
 Sort files according to their dependencies.
 
+\item["-build-tree" \var{path}]
+Tree where build artifacts are written.
+
+\item["-source-tree" \var{path}]
+Tree where dependencies are found.
+
 \item["-version"]
 Print version string and exit.
 

testsuite/tests/tool-ocamldep-tree/lib.ml

@@ -0,0 +1 @@
+let message = "Hello, world!"

testsuite/tests/tool-ocamldep-tree/main.compilers.reference

@@ -0,0 +1,11 @@
+$(OD)/lib.cmo $(OD)/lib.cmi : \
+    $(srcdir)/lib.ml
+$(OD)/lib.cmx $(OD)/lib.o $(OD)/lib.cmi : \
+    $(srcdir)/lib.ml
+$(OD)/main.cmo $(OD)/main.cmi : \
+    $(OD)/lib.cmi \
+    $(srcdir)/main.ml
+$(OD)/main.cmx $(OD)/main.o $(OD)/main.cmi : \
+    $(OD)/lib.cmi \
+    $(OD)/lib.cmx \
+    $(srcdir)/main.ml

testsuite/tests/tool-ocamldep-tree/main.ml

@@ -0,0 +1,9 @@
+(* TEST
+ modules = "lib.ml main.ml";
+ setup-ocamlc.byte-build-env;
+ commandline = "-depend -all -source-tree $(srcdir) -build-tree $(OD) lib.ml main.ml";
+ ocamlc.byte;
+ check-ocamlc.byte-output;
+ *)
+
+let () = print_endline Lib.message