{ "default-CC":
  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
  , "expression":
    { "type": "join"
    , "$1":
      { "type": "let*"
      , "bindings": [["fieldname", "defaults"], ["provider", "CC"]]
      , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
      }
    }
  }
, "default-CXX":
  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
  , "expression":
    { "type": "join"
    , "$1":
      { "type": "let*"
      , "bindings": [["fieldname", "defaults"], ["provider", "CXX"]]
      , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
      }
    }
  }
, "default-CFLAGS":
  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
  , "expression":
    { "type": "let*"
    , "bindings": [["fieldname", "defaults"], ["provider", "CFLAGS"]]
    , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
    }
  }
, "default-CXXFLAGS":
  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
  , "expression":
    { "type": "let*"
    , "bindings": [["fieldname", "defaults"], ["provider", "CXXFLAGS"]]
    , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
    }
  }
, "default-ENV":
  { "imports": {"provider_list": ["./", "..", "field_provider_list"]}
  , "expression":
    { "type": "let*"
    , "bindings":
      [ ["fieldname", "defaults"]
      , ["provider", "ENV"]
      , ["default", {"type": "empty_map"}]
      ]
    , "body": {"type": "CALL_EXPRESSION", "name": "provider_list"}
    }
  }
, "configure transition":
  { "expression":
    { "type": "let*"
    , "bindings":
      [ [ "OS"
        , { "type": "assert_non_empty"
          , "msg": "Missing field \"os\" for \"configure\"."
          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "os"}}
          }
        ]
      , [ "ARCH"
        , { "type": "assert_non_empty"
          , "msg": "Missing field \"arch\" for \"configure\"."
          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "arch"}}
          }
        ]
      , ["HOST_ARCH", {"type": "var", "name": "ARCH"}]
      , [ "TARGET_ARCH"
        , {"type": "join", "$1": {"type": "FIELD", "name": "target_arch"}}
        ]
      , [ "TARGET_ARCH"
        , { "type": "if"
          , "cond": {"type": "var", "name": "TARGET_ARCH"}
          , "then": {"type": "var", "name": "TARGET_ARCH"}
          , "else": {"type": "var", "name": "ARCH"}
          }
        ]
      ]
    , "body":
      { "type": "map_union"
      , "$1":
        [ { "type": "singleton_map"
          , "key": "OS"
          , "value": {"type": "var", "name": "OS"}
          }
        , { "type": "singleton_map"
          , "key": "ARCH"
          , "value": {"type": "var", "name": "TARGET_ARCH"}
          }
        , { "type": "singleton_map"
          , "key": "HOST_ARCH"
          , "value": {"type": "var", "name": "HOST_ARCH"}
          }
        , { "type": "singleton_map"
          , "key": "TARGET_ARCH"
          , "value": {"type": "var", "name": "TARGET_ARCH"}
          }
        ]
      }
    }
  }
, "compile-deps":
  { "doc": ["Collect compile dependencies (headers) from given target_fields"]
  , "vars": ["deps-fieldnames", "transition"]
  , "vars_doc":
    { "deps-fieldnames":
      ["List of target_field names to collect dependencies from."]
    , "transition": ["The optional configuration transition for the targets."]
    }
  , "imports":
    { "runfiles_list": ["./", "..", "field_runfiles_list"]
    , "provider_list": ["./", "..", "field_provider_list"]
    }
  , "expression":
    { "type": "disjoint_map_union"
    , "$1":
      { "type": "++"
      , "$1":
        { "type": "foreach"
        , "var": "fieldname"
        , "range": {"type": "var", "name": "deps-fieldnames"}
        , "body":
          { "type": "++"
          , "$1":
            { "type": "let*"
            , "bindings":
              [ ["provider", "compile-deps"]
              , ["default", {"type": "empty_map"}]
              ]
            , "body":
              [ {"type": "CALL_EXPRESSION", "name": "provider_list"}
              , {"type": "CALL_EXPRESSION", "name": "runfiles_list"}
              ]
            }
          }
        }
      }
    }
  }
, "link-deps":
  { "doc": ["Collect link dependencies (libraries) from given target_fields"]
  , "vars": ["deps-fieldnames", "transition"]
  , "vars_doc":
    { "deps-fieldnames":
      ["List of target_field names to collect dependencies from."]
    , "transition": ["The optional configuration transition for the targets."]
    }
  , "imports":
    { "artifacts_list": ["./", "..", "field_artifacts_list"]
    , "provider_list": ["./", "..", "field_provider_list"]
    }
  , "expression":
    { "type": "disjoint_map_union"
    , "$1":
      { "type": "++"
      , "$1":
        { "type": "foreach"
        , "var": "fieldname"
        , "range": {"type": "var", "name": "deps-fieldnames"}
        , "body":
          { "type": "++"
          , "$1":
            { "type": "let*"
            , "bindings":
              [["provider", "link-deps"], ["default", {"type": "empty_map"}]]
            , "body":
              [ {"type": "CALL_EXPRESSION", "name": "provider_list"}
              , {"type": "CALL_EXPRESSION", "name": "artifacts_list"}
              ]
            }
          }
        }
      }
    }
  }
, "link-args-deps":
  { "doc": ["Collect linker arguments from given target_fields"]
  , "vars": ["deps-fieldnames", "transition"]
  , "vars_doc":
    { "deps-fieldnames":
      ["List of target_field names to collect arguments from."]
    , "transition": ["The optional configuration transition for the targets."]
    }
  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
  , "expression":
    { "type": "++"
    , "$1":
      { "type": "foreach"
      , "var": "fieldname"
      , "range": {"type": "var", "name": "deps-fieldnames"}
      , "body":
        { "type": "let*"
        , "bindings": [["provider", "link-args"]]
        , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
        }
      }
    }
  }
, "objects":
  { "vars": ["CXX", "CXXFLAGS", "ENV", "srcs", "compile-deps", "local hdrs"]
  , "expression":
    { "type": "let*"
    , "bindings":
      [ [ "include tree"
        , { "type": "singleton_map"
          , "key": "include"
          , "value":
            {"type": "TREE", "$1": {"type": "var", "name": "compile-deps"}}
          }
        ]
      , [ "all hdrs"
        , { "type": "map_union"
          , "$1":
            [ {"type": "var", "name": "include tree"}
            , { "type": "to_subdir"
              , "subdir": "work"
              , "$1": {"type": "var", "name": "local hdrs"}
              }
            ]
          }
        ]
      ]
    , "body":
      { "type": "map_union"
      , "$1":
        { "type": "foreach_map"
        , "var_key": "src_name"
        , "var_val": "src_val"
        , "range": {"type": "var", "name": "srcs"}
        , "body":
          { "type": "let*"
          , "bindings":
            [ [ "work src_name"
              , { "type": "join"
                , "separator": "/"
                , "$1": ["work", {"type": "var", "name": "src_name"}]
                }
              ]
            , [ "inputs"
              , { "type": "map_union"
                , "$1":
                  [ {"type": "var", "name": "all hdrs"}
                  , { "type": "singleton_map"
                    , "key": {"type": "var", "name": "work src_name"}
                    , "value": {"type": "var", "name": "src_val"}
                    }
                  ]
                }
              ]
            , [ "out"
              , { "type": "change_ending"
                , "$1": {"type": "var", "name": "src_name"}
                , "ending": ".o"
                }
              ]
            , [ "work out"
              , { "type": "join"
                , "separator": "/"
                , "$1": ["work", {"type": "var", "name": "out"}]
                }
              ]
            , [ "action output"
              , { "type": "ACTION"
                , "outs": [{"type": "var", "name": "work out"}]
                , "inputs": {"type": "var", "name": "inputs"}
                , "env":
                  { "type": "var"
                  , "name": "ENV"
                  , "default": {"type": "empty_map"}
                  }
                , "cmd":
                  { "type": "++"
                  , "$1":
                    [ [{"type": "var", "name": "CXX"}]
                    , {"type": "var", "name": "CXXFLAGS"}
                    , ["-I", "work", "-isystem", "include"]
                    , ["-c", {"type": "var", "name": "work src_name"}]
                    , ["-o", {"type": "var", "name": "work out"}]
                    ]
                  }
                }
              ]
            , [ "staged output artifact"
              , { "type": "map_union"
                , "$1":
                  { "type": "foreach_map"
                  , "range": {"type": "var", "name": "action output"}
                  , "var_val": "object"
                  , "body":
                    { "type": "singleton_map"
                    , "key": {"type": "var", "name": "out"}
                    , "value": {"type": "var", "name": "object"}
                    }
                  }
                }
              ]
            ]
          , "body": {"type": "var", "name": "staged output artifact"}
          }
        }
      }
    }
  }
, "compiler":
  { "vars": ["CC", "CXX"]
  , "imports": {"default-CC": "default-CC", "default-CXX": "default-CXX"}
  , "expression":
    { "type": "if"
    , "cond": {"type": "FIELD", "name": "pure C"}
    , "then":
      { "type": "var"
      , "name": "CC"
      , "default": {"type": "CALL_EXPRESSION", "name": "default-CC"}
      }
    , "else":
      { "type": "var"
      , "name": "CXX"
      , "default": {"type": "CALL_EXPRESSION", "name": "default-CXX"}
      }
    }
  }
, "flags":
  { "vars": ["CFLAGS", "CXXFLAGS"]
  , "imports":
    { "default-CFLAGS": "default-CFLAGS"
    , "default-CXXFLAGS": "default-CXXFLAGS"
    }
  , "expression":
    { "type": "if"
    , "cond": {"type": "FIELD", "name": "pure C"}
    , "then":
      { "type": "var"
      , "name": "CFLAGS"
      , "default": {"type": "CALL_EXPRESSION", "name": "default-CFLAGS"}
      }
    , "else":
      { "type": "var"
      , "name": "CXXFLAGS"
      , "default": {"type": "CALL_EXPRESSION", "name": "default-CXXFLAGS"}
      }
    }
  }
, "lib artifact":
  { "vars":
    [ "CXX"
    , "CXXFLAGS"
    , "CC"
    , "CFLAGS"
    , "ENV"
    , "AR"
    , "srcs"
    , "hdrs"
    , "private-hdrs"
    , "local cflags"
    , "compile-deps"
    ]
  , "imports":
    { "compiler": "compiler"
    , "flags": "flags"
    , "objects": "objects"
    , "default-ENV": "default-ENV"
    }
  , "expression":
    { "type": "let*"
    , "bindings":
      [ [ "stage"
        , { "type": "join"
          , "separator": "/"
          , "$1": {"type": "FIELD", "name": "stage"}
          }
        ]
      , ["CXX", {"type": "CALL_EXPRESSION", "name": "compiler"}]
      , ["CXXFLAGS", {"type": "CALL_EXPRESSION", "name": "flags"}]
      , [ "CXXFLAGS"
        , { "type": "++"
          , "$1":
            [ {"type": "var", "name": "CXXFLAGS"}
            , {"type": "var", "name": "local cflags", "default": []}
            ]
          }
        ]
      , [ "ENV"
        , { "type": "map_union"
          , "$1":
            { "type": "++"
            , "$1":
              [ {"type": "CALL_EXPRESSION", "name": "default-ENV"}
              , [ { "type": "var"
                  , "name": "ENV"
                  , "default": {"type": "empty_map"}
                  }
                ]
              ]
            }
          }
        ]
      , ["deps-fieldnames", ["deps", "proto-deps"]]
      , [ "local hdrs"
        , { "type": "disjoint_map_union"
          , "$1":
            [ {"type": "var", "name": "hdrs"}
            , {"type": "var", "name": "private-hdrs"}
            ]
          }
        ]
      , ["objects", {"type": "CALL_EXPRESSION", "name": "objects"}]
      , [ "base name"
        , { "type": "let*"
          , "bindings":
            [ [ "name"
              , {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
              ]
            ]
          , "body":
            { "type": "if"
            , "cond": {"type": "var", "name": "objects"}
            , "then":
              { "type": "assert_non_empty"
              , "msg": "A name has to be provided for non-header-only libraries"
              , "$1": {"type": "var", "name": "name"}
              }
            , "else": {"type": "var", "name": "name"}
            }
          }
        ]
      , [ "libname"
        , { "type": "join"
          , "$1": ["lib", {"type": "var", "name": "base name"}, ".a"]
          }
        ]
      , [ "lib"
        , { "type": "if"
          , "cond": {"type": "var", "name": "objects"}
          , "else": {"type": "empty_map"}
          , "then":
            { "type": "ACTION"
            , "outs": [{"type": "var", "name": "libname"}]
            , "inputs": {"type": "var", "name": "objects"}
            , "env":
              {"type": "var", "name": "ENV", "default": {"type": "empty_map"}}
            , "cmd":
              { "type": "++"
              , "$1":
                [ [ {"type": "var", "name": "AR", "default": "ar"}
                  , "cqs"
                  , {"type": "var", "name": "libname"}
                  ]
                , {"type": "keys", "$1": {"type": "var", "name": "objects"}}
                ]
              }
            }
          }
        ]
      ]
    , "body":
      { "type": "to_subdir"
      , "subdir": {"type": "var", "name": "stage"}
      , "$1": {"type": "var", "name": "lib"}
      }
    }
  }
, "lib result":
  { "vars":
    [ "CXX"
    , "CXXFLAGS"
    , "CC"
    , "CFLAGS"
    , "ENV"
    , "AR"
    , "srcs"
    , "hdrs"
    , "private-hdrs"
    , "local cflags"
    , "link external"
    , "extra-provides"
    ]
  , "imports":
    { "compile-deps": "compile-deps"
    , "link-deps": "link-deps"
    , "link-args-deps": "link-args-deps"
    , "lib artifact": "lib artifact"
    }
  , "expression":
    { "type": "let*"
    , "bindings":
      [ ["deps-fieldnames", ["deps", "proto-deps"]]
      , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
      , ["link-deps", {"type": "CALL_EXPRESSION", "name": "link-deps"}]
      , ["lib", {"type": "CALL_EXPRESSION", "name": "lib artifact"}]
      , [ "link-args"
        , { "type": "nub_right"
          , "$1":
            { "type": "++"
            , "$1":
              [ {"type": "keys", "$1": {"type": "var", "name": "lib"}}
              , {"type": "var", "name": "link external", "default": []}
              , {"type": "CALL_EXPRESSION", "name": "link-args-deps"}
              ]
            }
          }
        ]
      ]
    , "body":
      { "type": "RESULT"
      , "artifacts": {"type": "var", "name": "lib"}
      , "runfiles": {"type": "var", "name": "hdrs"}
      , "provides":
        { "type": "map_union"
        , "$1":
          [ { "type": "singleton_map"
            , "key": "compile-deps"
            , "value": {"type": "var", "name": "compile-deps"}
            }
          , { "type": "singleton_map"
            , "key": "link-deps"
            , "value": {"type": "var", "name": "link-deps"}
            }
          , { "type": "singleton_map"
            , "key": "link-args"
            , "value": {"type": "var", "name": "link-args"}
            }
          , { "type": "var"
            , "name": "extra-provides"
            , "default": {"type": "empty_map"}
            }
          ]
        }
      }
    }
  }
}