LibIndex.get hangs in UTop

[kandu]

Hi, dear ocp-index developers. I recently encountered an issue working with ocp-index.lib, here is the step-to-reproduce:

#require "ocp-index.lib";;

let cmd_input_line cmd =
  try
    let ic = Unix.open_process_in (cmd ^ " 2>/dev/null") in
    let r = input_line ic in
    let r =
      let len = String.length r in
      if len>0 && r.[len - 1] = '\r' then String.sub r 0 (len-1) else r
    in
    match Unix.close_process_in ic with
    | Unix.WEXITED 0 -> r
    | _ -> failwith "cmd_input_line"
  with
  | End_of_file | Unix.Unix_error _ | Sys_error _ -> failwith "cmd_input_line"

let index=
  let ocaml_lib= try (cmd_input_line) "ocamlc -where" with _-> "" in
  let opam_lib= try (cmd_input_line) "opam config var lib" with _-> "" in
  LibIndex.load @@ LibIndex.Misc.unique_subdirs [ocaml_lib; opam_lib]
;;

LibIndex.Print.info (LibIndex.get index "String.concat");;

#require "core_kernel";;

LibIndex.Print.info (LibIndex.get index "Core_kernel.String.concat");;

Paste the code above to utop, LibIndex.get hangs at the last statement.

Buf if I replace the last three statements with only the last one, or just delete the #require "core_kernel";; statement, LibIndex.get will work.

There could be some conflicts between #require and LibIndex's internal implementation.

and here is the backtrace info

^CInterrupted.
Raised by primitive operation at file "typing/env.ml", line 1039, characters 6-43
Re-raised at file "typing/env.ml", line 1012, characters 2-164
Called from file "typing/printtyp.ml", line 289, characters 7-36
Called from file "typing/printtyp.ml", line 278, characters 13-46
Re-raised at file "typing/printtyp.ml", line 303, characters 20-256
Called from file "typing/printtyp.ml", line 330, characters 25-63
Called from file "utils/tbl.ml", line 105, characters 16-21
Called from file "typing/env.ml", line 1452, characters 10-120
Called from file "list.ml", line 100, characters 12-15
Called from file "typing/env.ml", line 1475, characters 2-29
Called from file "typing/printtyp.ml", line 391, characters 36-70
Called from file "typing/printtyp.ml", line 515, characters 23-39
Called from file "typing/printtyp.ml", line 767, characters 29-52
Called from file "typing/printtyp.ml", line 996, characters 11-44
Called from file "typing/printtyp.ml", line 1260, characters 7-40
Called from file "typing/printtyp.ml", line 1254, characters 18-39
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1256, characters 14-58
Called from file "typing/printtyp.ml", line 1184, characters 13-22
Called from file "typing/printtyp.ml", line 1226, characters 27-47
Called from file "typing/printtyp.ml", line 1289, characters 30-59
Called from file "libs/indexBuild.ml", line 552, characters 16-41
Called from file "libs/indexBuild.ml", line 628, characters 17-137
Called from file "libs/indexMisc.ml", line 36, characters 38-58
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from unknown location
Called from file "libs/indexBuild.ml", line 628, characters 17-137
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from unknown location
Called from file "libs/indexBuild.ml", line 628, characters 17-137
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from unknown location
Called from file "libs/indexBuild.ml", line 1077, characters 24-164
Called from file "libs/indexMisc.ml", line 36, characters 38-58
Called from file "libs/indexBuild.ml", line 1073, characters 17-514
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from unknown location
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from unknown location
Called from file "libs/indexBuild.ml", line 746, characters 16-51
Called from file "list.ml", line 111, characters 24-34
Called from file "libs/indexBuild.ml", line 1094, characters 11-89
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 149, characters 42-53
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 42, characters 8-25
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 42, characters 8-25
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 42, characters 8-25
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 141, characters 8-25
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 60, characters 8-22
Called from file "list.ml", line 111, characters 24-34
Called from file "libs/indexBuild.ml", line 1094, characters 11-89
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 149, characters 42-53
Called from file "camlinternalLazy.ml", line 27, characters 17-27
Re-raised at file "camlinternalLazy.ml", line 34, characters 10-11
Called from file "libs/trie.ml", line 83, characters 35-52
Called from file "libs/trie.ml", line 86, characters 6-19
Called from file "libs/trie.ml", line 89, characters 8-26
Called from file "//toplevel//", line 2, characters 20-81
Called from file "toplevel/toploop.ml", line 180, characters 17-56

[AltGr]

Interesting... thanks for the very helpful report.
I couldn't reproduce with rlwrap ocaml; do you know if utop is doing specific stuff that could interfere ?
I am not familiar with utop, and couldn't get past the first #require:

utop # #require "ocp-index.lib";;
Error: Reference to undefined global `Location'

what does it require that plain ocaml doesn't ??

[kandu]

Sorry. you can invoke utop-full and then #require "ocp-index.lib"

do you know if utop is doing specific stuff that could interfere ?

The backtrace tells that it struggled in typing/env.ml and typing/printtyp.ml, https://github.com/ocaml-community/utop/blob/master/src/lib/uTop_main.mli is suspicious.

compiler-libs, lazy-evalution, global variables, what a wonderful integration to debug with ;)

[Drup]

The interaction is when you link utop and libindex together. utop non-full is expunged, which avoids the issue. @kandu It would probably be easier with a compiled examples, not one that requires to run stuff in utop-full, as expunging is going to muddy the waters.

[pmetzger]

What should we do to get this resolved?