Dune crash stacktrace and _build/log

gistfile1.txt

Internal error, please report upstream including the contents of _build/log.
Description:
  ("Syntax identifier is unset",
  { name = "menhir"
  ; supported_versions =
      { version_map =
          map
            { 1 : map { 0 : (1, 0); 1 : (1, 4) }
            ; 2 : map { 0 : (1, 4); 1 : (2, 2) }
            }
      ; deleted_in = map {}
      }
  ; context =
      map
        { "pform decoding environment" :
            { syntax_version = (3, 0)
            ; vars =
                map
                  { "-verbose" : Deleted_in Nothing,(3, 0),[]
                  ; "<" :
                      Deleted_in
                        First_dep,(1, 0),[ "Use a named dependency instead:\n\
                                            \n\
                                           \  (deps (:x <dep>) ...)\n\
                                           \   ... %{x}\n\
                                            ..."
                                         ]
                  ; "@" : Renamed_in Deps,(1, 0),"targets"
                  ; "ARCH_SIXTYFOUR" :
                      Renamed_in Arch_sixtyfour,(1, 0),"arch_sixtyfour"
                  ; "CC" : Renamed_in Cc,(1, 0),"cc"
                  ; "CPP" : Renamed_in Cpp,(1, 0),"cpp"
                  ; "CXX" : Renamed_in Cxx,(1, 0),"cxx"
                  ; "MAKE" : Renamed_in Make,(1, 0),"make"
                  ; "OCAML" : Renamed_in Ocaml,(1, 0),"ocaml"
                  ; "OCAMLC" : Renamed_in Ocamlc,(1, 0),"ocamlc"
                  ; "OCAMLOPT" : Renamed_in Ocamlopt,(1, 0),"ocamlopt"
                  ; "PA_CPP" : Renamed_in Pa_cpp,(1, 0),"pa_cpp"
                  ; "ROOT" :
                      Renamed_in Workspace_root,(1, 0),"workspace_root"
                  ; "SCOPE_ROOT" :
                      Renamed_in Project_root,(1, 0),"project_root"
                  ; "^" : Renamed_in Targets,(1, 0),"deps"
                  ; "arch_sixtyfour" : No_info Arch_sixtyfour
                  ; "architecture" : Since Architecture,(1, 10)
                  ; "cc" : No_info Cc
                  ; "ccomp_type" : Since Ccomp_type,(3, 0)
                  ; "context_name" : No_info Context_name
                  ; "corrected-suffix" : No_info Corrected_suffix
                  ; "cpp" : No_info Cpp
                  ; "cxx" : No_info Cxx
                  ; "deps" : Since Deps,(1, 0)
                  ; "ext_asm" : No_info Ext_asm
                  ; "ext_dll" : No_info Ext_dll
                  ; "ext_exe" : No_info Ext_exe
                  ; "ext_lib" : No_info Ext_lib
                  ; "ext_obj" : No_info Ext_obj
                  ; "ext_plugin" : Since Ext_plugin,(2, 4)
                  ; "ignoring_promoted_rules" :
                      Since Ignoring_promoted_rules,(1, 10)
                  ; "impl-files" : No_info Impl_files
                  ; "inline_tests" : No_info Inline_tests
                  ; "input-file" : Since Input_file,(1, 0)
                  ; "intf-files" : No_info Intf_files
                  ; "library-name" : No_info Library_name
                  ; "make" : No_info Make
                  ; "model" : Since Model,(1, 10)
                  ; "null" : No_info Dev_null
                  ; "ocaml" : No_info Ocaml
                  ; "ocaml_bin" : No_info Ocaml_bin_dir
                  ; "ocaml_version" : No_info Ocaml_version
                  ; "ocaml_where" : No_info Ocaml_stdlib_dir
                  ; "ocamlc" : No_info Ocamlc
                  ; "ocamlopt" : No_info Ocamlopt
                  ; "os_type" : Since Os_type,(1, 10)
                  ; "pa_cpp" : No_info Pa_cpp
                  ; "partition" : Since Partition,(3, 8)
                  ; "profile" : No_info Profile
                  ; "project_root" : Since Project_root,(1, 0)
                  ; "system" : Since System,(1, 10)
                  ; "target" : Since Target,(1, 11)
                  ; "targets" : Since Targets,(1, 0)
                  ; "test" : No_info Test
                  ; "toolchains" : Since Toolchain,(3, 0)
                  ; "workspace_root" : No_info Workspace_root
                  }
            ; macros =
                map
                  { "bin" : No_info "Bin"
                  ; "bin-available" : Since "Bin_available",(3, 0)
                  ; "cma" : Since Artifact Lib byte,(2, 0)
                  ; "cmi" : Since Artifact Mod cmi,(2, 0)
                  ; "cmo" : Since Artifact Mod cmo,(2, 0)
                  ; "cmx" : Since Artifact Mod cmx,(2, 0)
                  ; "cmxa" : Since Artifact Lib native,(2, 0)
                  ; "coq" : No_info "Coq_config"
                  ; "dep" : Since "Dep",(1, 0)
                  ; "env" : Since "Env",(1, 4)
                  ; "exe" : No_info "Exe"
                  ; "findlib" :
                      Renamed_in
                        Lib { lib_exec = false; lib_private = false },
                        (1, 0),"lib"
                  ; "lib" :
                      No_info Lib { lib_exec = false; lib_private = false }
                  ; "lib-available" : No_info "Lib_available"
                  ; "lib-private" :
                      Since
                        Lib { lib_exec = false; lib_private = true },
                        (2, 1)
                  ; "libexec" :
                      No_info Lib { lib_exec = true; lib_private = false }
                  ; "libexec-private" :
                      Since
                        Lib { lib_exec = true; lib_private = true },(2, 1)
                  ; "ocaml-config" : No_info "Ocaml_config"
                  ; "path" : Renamed_in "Dep",(1, 0),"dep"
                  ; "path-no-dep" : Deleted_in "Path_no_dep",(1, 0),[]
                  ; "read" : No_info "Read"
                  ; "read-lines" : No_info "Read_lines"
                  ; "read-strings" : No_info "Read_strings"
                  ; "version" : No_info "Version"
                  }
            }
        ; "dune" : (3, 0)
        }
  })
Raised at Stdune__Code_error.raise in file
  "otherlibs/stdune/src/code_error.ml", line 10, characters 30-62
Called from Dune_sexp__Decoder.(>>|) in file "src/dune_sexp/decoder.ml", line
  137, characters 2-5
Called from Dune_sexp__Decoder.(>>=) in file "src/dune_sexp/decoder.ml"
  (inlined), line 131, characters 17-28
Called from Dune_sexp__Syntax.since in file "src/dune_sexp/syntax.ml", line
  499, characters 2-310
Called from Dune_sexp__Decoder.(>>>) in file "src/dune_sexp/decoder.ml"
  (inlined), line 141, characters 18-29
Called from Dune_rules__Dune_env.Stanza.menhir_flags in file
  "src/dune_rules/dune_env.ml", line 22, characters 22-82
Called from Dune_sexp__Decoder.field_o in file "src/dune_sexp/decoder.ml",
  line 649, characters 23-37
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  150, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  149, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  149, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  149, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  149, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  149, characters 17-28
Called from Dune_sexp__Decoder.(>>|) in file "src/dune_sexp/decoder.ml", line
  136, characters 17-28
Called from Dune_sexp__Decoder.fields in file "src/dune_sexp/decoder.ml",
  line 684, characters 21-53
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  150, characters 17-28
Called from Dune_sexp__Decoder.(>>|) in file "src/dune_sexp/decoder.ml", line
  136, characters 17-28
Called from Dune_sexp__Decoder.enter.(fun) in file
  "src/dune_sexp/decoder.ml", line 384, characters 17-26
Called from Dune_sexp__Decoder.next_with_user_context in file
  "src/dune_sexp/decoder.ml" (inlined), line 291, characters 21-50
Called from Dune_sexp__Decoder.enter in file "src/dune_sexp/decoder.ml", line
  380, characters 2-232
Called from Dune_sexp__Decoder.repeat.loop in file
  "src/dune_sexp/decoder.ml", line 212, characters 17-24
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  150, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  149, characters 17-28
Called from Dune_sexp__Decoder.(>>|) in file "src/dune_sexp/decoder.ml", line
  136, characters 17-28
Called from Dune_sexp__Decoder.and+ in file "src/dune_sexp/decoder.ml", line
  150, characters 17-28
Called from Dune_sexp__Decoder.(>>|) in file "src/dune_sexp/decoder.ml", line
  136, characters 17-28
Called from Dune_sexp__Decoder.capture.f in file "src/dune_sexp/decoder.ml",
  line 263, characters 23-36
Called from CamlinternalLazy.force_lazy_block in file "camlinternalLazy.ml",
  line 31, characters 17-27
Re-raised at CamlinternalLazy.force_lazy_block in file "camlinternalLazy.ml",
  line 36, characters 4-11
Called from Dune_rules__Workspace.step1 in file
  "src/dune_rules/workspace.ml", line 621, characters 17-31
Called from CamlinternalLazy.force_lazy_block in file "camlinternalLazy.ml",
  line 31, characters 17-27
Re-raised at CamlinternalLazy.force_lazy_block in file "camlinternalLazy.ml",
  line 36, characters 4-11
Called from Fiber__Core.O.(>>|).(fun) in file "vendor/fiber/src/core.ml",
  line 252, characters 36-41
Called from Fiber__Scheduler.exec in file "vendor/fiber/src/scheduler.ml",
  line 76, characters 8-11
-> required by ("workspace", ())
-> required by ("build-contexts", ())
-> required by ("toplevel", ())

I must not crash.  Uncertainty is the mind-killer. Exceptions are the
little-death that brings total obliteration.  I will fully express my cases. 
Execution will pass over me and through me.  And when it has gone past, I
will unwind the stack along its path.  Where the cases are handled there will
be nothing.  Only I will remain.

========
# dune build
# OCAMLPARAM: unset
# Shared cache: disabled
# Workspace root: /home/kn/foo
# Auto-detected concurrency: 4