conf-bap-llvm 1.5

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 ocaml-base-compiler 5.1.1*  [upstream or system changes]
  - recompile ocaml-config        3       [upstream or system changes]
  - recompile ocaml               5.1.1   [uses ocaml-base-compiler, ocaml-config]
  - recompile opam-depext         1.2.1-1
  - recompile base-domains        base    [uses ocaml]
  - recompile base-nnp            base    [uses base-domains]
===== 6 to recompile =====

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
-> retrieved ocaml-config.3  (cached)
-> retrieved opam-depext.1.2.1-1  (cached)
-> retrieved ocaml-base-compiler.5.1.1  (cached)
-> removed   base-nnp.base
-> removed   base-domains.base
-> removed   opam-depext.1.2.1-1
-> removed   ocaml.5.1.1
-> removed   ocaml-config.3
-> removed   ocaml-base-compiler.5.1.1
-> installed ocaml-base-compiler.5.1.1
-> installed ocaml-config.3
-> installed ocaml.5.1.1
-> installed base-domains.base
-> installed base-nnp.base
-> 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 conf-bap-llvm.1.5 conf-which.1" <><><><><>

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 conf-bap-llvm.1.5 & conf-which.1:   * Missing dependency:
            - conf-bap-llvm >= 1.4
            depends on the unavailable system package 'llvm-9-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=conf-bap-llvm.1.5,conf-which.1' returned 20