hardcaml-llvmsim 0.2

Error log

The package failed to build. The error log from opam follows.

Opam plugin "depext" may require upgrading/reinstalling. Reinstall the plugin on the current switch? [Y/n] y
The following actions will be performed:
  - recompile opam-depext 1.2.1-1

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved opam-depext.1.2.1-1  (cached)
-> removed   opam-depext.1.2.1-1
-> installed opam-depext.1.2.1-1
Done.

<><> opam-depext.1.2.1-1 installed successfully <><><><><><><><><><><><><><><><>
=> opam-depext is unnecessary when used with opam >= 2.1. Please use opam install directly instead
# Run eval $(opam env) to update the current shell environment

<><> Carrying on to "opam depext -viy hardcaml-llvmsim.0.2 yojson.2.1.2 uchar.0.0.2 topkg.1.0.7 stdlib-shims.0.3.0 sexplib0.v0.15.0 seq.base ppxlib.0.31.0 ppx_derivers.1.2.1 ocamlfind.1.9.6 ocamlbuild.0.14.3 ocaml-compiler-libs.v0.12.4 num.1.5 menhirSdk.20230608 menhirLib.20230608 menhir.20230608 llvm.3.5 js_of_ocaml-compiler.4.0.0 js_of_ocaml-camlp4.3.1.0 js_of_ocaml.4.0.0 jbuilder.1.0+beta20.2 integers.0.7.0 hardcaml.1.2.0 dune-configurator.3.13.0 dune.3.13.0 ctypes-foreign.0.21.1 ctypes.0.21.1 csexp.1.5.2 cppo.1.6.9 conf-pkg-config.3 conf-libffi.2.0.0 cmdliner.1.0.4 camlp4.4.07+1 bigarray-compat.1.1.0 base-bytes.base astring.0.8.5" 

You are using opam 2.1+, where external dependency handling has been integrated: consider calling opam directly, the 'depext' plugin interface is provided for backwards compatibility only
# Detecting depexts using vars: arch=x86_64, os=linux, os-distribution=debian, os-family=debian
[ERROR] No solution for hardcaml-llvmsim.0.2 & yojson.2.1.2 & uchar.0.0.2 & topkg.1.0.7 & stdlib-shims.0.3.0 & sexplib0.v0.15.0 & seq.base & ppxlib.0.31.0 & ppx_derivers.1.2.1 & ocamlfind.1.9.6 & ocamlbuild.0.14.3 & ocaml-compiler-libs.v0.12.4 & num.1.5 & menhirSdk.20230608 & menhirLib.20230608 & menhir.20230608 & llvm.3.5 & js_of_ocaml-compiler.4.0.0 & js_of_ocaml-camlp4.3.1.0 & js_of_ocaml.4.0.0 & jbuilder.1.0+beta20.2 & integers.0.7.0 & hardcaml.1.2.0 & dune-configurator.3.13.0 & dune.3.13.0 & ctypes-foreign.0.21.1 & ctypes.0.21.1 & csexp.1.5.2 & cppo.1.6.9 & conf-pkg-config.3 & conf-libffi.2.0.0 & cmdliner.1.0.4 & camlp4.4.07+1 & bigarray-compat.1.1.0 & base-bytes.base & astring.0.8.5:   * Missing dependency:
            - llvm = 3.5
            depends on the unavailable system package 'llvm-3.5-dev'. Use `--no-depexts' to attempt installation anyway, or it is possible that a depext package name in the opam file is incorrect.


Command failed: opam --cli=2.1 list --readonly --external '--resolve=hardcaml-llvmsim.0.2,yojson.2.1.2,uchar.0.0.2,topkg.1.0.7,stdlib-shims.0.3.0,sexplib0.v0.15.0,seq.base,ppxlib.0.31.0,ppx_derivers.1.2.1,ocamlfind.1.9.6,ocamlbuild.0.14.3,ocaml-compiler-libs.v0.12.4,num.1.5,menhirSdk.20230608,menhirLib.20230608,menhir.20230608,llvm.3.5,js_of_ocaml-compiler.4.0.0,js_of_ocaml-camlp4.3.1.0,js_of_ocaml.4.0.0,jbuilder.1.0+beta20.2,integers.0.7.0,hardcaml.1.2.0,dune-configurator.3.13.0,dune.3.13.0,ctypes-foreign.0.21.1,ctypes.0.21.1,csexp.1.5.2,cppo.1.6.9,conf-pkg-config.3,conf-libffi.2.0.0,cmdliner.1.0.4,camlp4.4.07+1,bigarray-compat.1.1.0,base-bytes.base,astring.0.8.5' returned 20