Unable to install Merlin merlin.4.7-413 on Ubuntu 25.04

[daimrod]

Hi,

I am unable to install merlin 4.7-413 on Ubuntu 25.04 with OCaml compiler 4.13.1.

I was following the setup instructions from Real World OCaml: https://dev.realworldocaml.org/install.html
The error is similar to the issue #1478.

$ opam install merlin
The following actions will be performed:
=== install 1 package
  ∗ merlin 4.7-413

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
⬇ retrieved merlin.4.7-413  (cached)
[ERROR] The compilation of merlin.4.7-413 failed at "dune build -p merlin -j 7".

#=== ERROR while compiling merlin.4.7-413 =====================================#
# context     2.4.1 | linux/x86_64 | ocaml-base-compiler.4.13.1 | https://opam.ocaml.org#21f97b2e6d7c617fc0a79cc8e59b2e10690960e1
# path        ~/.opam/4.13.1/.opam-switch/build/merlin.4.7-413
# command     ~/.opam/opam-init/hooks/sandbox.sh build dune build -p merlin -j 7
# exit-code   1
# env-file    ~/.opam/log/merlin-65231-dfbc0e.env
# output-file ~/.opam/log/merlin-65231-dfbc0e.out
### output ###
# [...]
# ocamlmerlin.c:377:41: warning: ‘__builtin___snprintf_chk’ output may be truncated before the last format character [-Wformat-truncation=]
#   377 |     snprintf(socket_path, PATHSZ, "%s/%s", path_socketdir(), socketname);
#       |                                         ^
# In function ‘snprintf’,
#     inlined from ‘start_server.constprop’ at ocamlmerlin.c:377:5:
# /usr/include/x86_64-linux-gnu/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output 2 or more bytes (assuming 4098) into a destination of size 4097
#    68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
#       |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#    69 |                                    __glibc_objsize (__s), __fmt,
#       |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#    70 |                                    __va_arg_pack ());
#       |                                    ~~~~~~~~~~~~~~~~~

<><> Error report <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
┌─ The following actions failed
│ λ build merlin 4.7-413
└─ 
╶─ No changes have been performed

[voodoos]

Thanks for your report @daimrod

The "output" part of the message doesn't look like the actual error, it is "just" a warning.
Could you share the whole log in ~/.opam/log/merlin-65231-dfbc0e.out ?

[MisterDA]

The problem is this seq library that should have been removed with OCaml 4.07, I think:

# syntax=docker/dockerfile:1
FROM ocaml/opam:ubuntu-25.04-ocaml-4.13
RUN sudo ln -sf /usr/bin/opam-2.4 /usr/bin/opam && opam init --reinit -ni
RUN --mount=type=cache,target=/home/opam/.opam/download-cache,sharing=locked,uid=1000,gid=1000 \
    opam install -y --deps-only merlin

gives

21.47 # File "src/frontend/ocamlmerlin/dune", line 17, characters 37-40:
21.47 # 17 |             ocaml_typing ocaml_utils seq))
21.47 #                                           ^^^
21.47 # Error: Library "seq" not found.
21.47 # -> required by _build/default/src/frontend/ocamlmerlin/ocamlmerlin_server.exe
21.47 # -> required by _build/install/default/bin/ocamlmerlin-server
21.47 # -> required by _build/default/merlin.install
21.47 # -> required by alias install

with the patch applied there's the warnings but not the build failure:

# syntax=docker/dockerfile:1
FROM ocaml/opam:ubuntu-25.04-ocaml-4.13
RUN sudo ln -sf /usr/bin/opam-2.4 /usr/bin/opam && opam init --reinit -ni
ADD --keep-git-dir --link --chown=1000:1000 https://github.com/ocaml/merlin.git#v4.7-413 /home/opam/merlin
RUN git config --global --add safe.directory ~/merlin
WORKDIR /home/opam/merlin
RUN --mount=type=cache,target=/home/opam/.opam/download-cache,sharing=locked,uid=1000,gid=1000 \
    opam install -y --deps-only --with-dev --formula='"menhir" {<= "20220210"}' merlin.4.7-413
RUN patch -p1 <<'EOF'
diff --git a/src/frontend/ocamlmerlin/dune b/src/frontend/ocamlmerlin/dune
index faa01b93..cc549032 100644
--- a/src/frontend/ocamlmerlin/dune
+++ b/src/frontend/ocamlmerlin/dune
@@ -14,7 +14,7 @@
  (modules (:standard \ gen_ccflags))
  (libraries config yojson merlin_analysis merlin_kernel
             merlin_utils os_ipc ocaml_parsing query_protocol query_commands
-            ocaml_typing ocaml_utils seq))
+            ocaml_typing ocaml_utils))

 (executable
  (name      gen_ccflags)
EOF
RUN opam exec -- make -j1

[daimrod]

Sorry for the delay.
Here is the content of the ~/.opam/log/merlin-XXX.out file:

File "src/frontend/ocamlmerlin/dune", line 17, characters 37-40:
17 |             ocaml_typing ocaml_utils seq))
                                          ^^^
Error: Library "seq" not found.
-> required by _build/default/src/frontend/ocamlmerlin/ocamlmerlin_server.exe
-> required by _build/install/default/bin/ocamlmerlin-server
-> required by _build/default/merlin.install
-> required by alias install
(cd _build/default/src/frontend/ocamlmerlin && /usr/bin/gcc -O2 -fno-strict-aliasing -fwrapv -pthread -fPIC -oocamlmerlin.exe ocamlmerlin.c)
ocamlmerlin.c: In function ‘connect_socket.constprop’:
ocamlmerlin.c:262:40: warning: ‘%s’ directive output may be truncated writing up to 4096 bytes into a region of size 102 [-Wformat-truncation=]
  262 |     snprintf(address.sun_path, 104, "./%s", socketname);
      |                                        ^~
In file included from /usr/include/stdio.h:970,
                 from ocamlmerlin.c:2:
In function ‘snprintf’,
    inlined from ‘connect_socket.constprop’ at ocamlmerlin.c:262:5:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output between 3 and 4099 bytes into a destination of size 104
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
ocamlmerlin.c: In function ‘start_server.constprop’:
ocamlmerlin.c:353:40: warning: ‘%s’ directive output may be truncated writing up to 4096 bytes into a region of size 102 [-Wformat-truncation=]
  353 |     snprintf(address.sun_path, 104, "./%s", socketname);
      |                                        ^~
In function ‘snprintf’,
    inlined from ‘start_server.constprop’ at ocamlmerlin.c:353:5:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output between 3 and 4099 bytes into a destination of size 104
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~
ocamlmerlin.c: In function ‘start_server.constprop’:
ocamlmerlin.c:377:41: warning: ‘__builtin___snprintf_chk’ output may be truncated before the last format character [-Wformat-truncation=]
  377 |     snprintf(socket_path, PATHSZ, "%s/%s", path_socketdir(), socketname);
      |                                         ^
In function ‘snprintf’,
    inlined from ‘start_server.constprop’ at ocamlmerlin.c:377:5:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:68:10: note: ‘__builtin___snprintf_chk’ output 2 or more bytes (assuming 4098) into a destination of size 4097
   68 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   69 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   70 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~

Thanks for the help.