{ "defaults":
  { "doc": ["A rule to provide defaults for pkgconfig"]
  , "string_fields": ["pkg-config", "PATH", "PKG_CONFIG_PATH"]
  , "target_fields": ["base"]
  , "field_doc":
    { "pkg-config":
      ["The name of the pkg-config binary to use, potentially with full path."]
    , "PATH": ["Additional paths to add to \"PATH\" when calling pkg-config"]
    , "PKG_CONFIG_PATH":
      [ "Additional paths to add to \"PKG_CONFIG_PATH\" when calling pkg-config"
      ]
    , "base": ["Other targets (using the same rule) to inherit from."]
    }
  , "imports":
    { "base-provides": ["./", "..", "defaults-base-provides"]
    , "base-provides-++": ["./", "..", "defaults-base-provides-++"]
    }
  , "expression":
    { "type": "let*"
    , "bindings":
      [ ["pkg-config", {"type": "FIELD", "name": "pkg-config"}]
      , ["provider", "pkg-config"]
      , [ "pkg-config"
        , { "type": "if"
          , "cond": {"type": "var", "name": "pkg-config"}
          , "then": {"type": "var", "name": "pkg-config"}
          , "else": {"type": "CALL_EXPRESSION", "name": "base-provides"}
          }
        ]
      , ["PATH", {"type": "FIELD", "name": "PATH"}]
      , ["provider", "PATH"]
      , [ "PATH"
        , { "type": "nub_left"
          , "$1":
            { "type": "++"
            , "$1":
              [ {"type": "var", "name": "PATH"}
              , {"type": "CALL_EXPRESSION", "name": "base-provides-++"}
              ]
            }
          }
        ]
      , ["PKG_CONFIG_PATH", {"type": "FIELD", "name": "PKG_CONFIG_PATH"}]
      , ["provider", "PKG_CONFIG_PATH"]
      , [ "PKG_CONFIG_PATH"
        , { "type": "nub_left"
          , "$1":
            { "type": "++"
            , "$1":
              [ {"type": "var", "name": "PKG_CONFIG_PATH"}
              , {"type": "CALL_EXPRESSION", "name": "base-provides-++"}
              ]
            }
          }
        ]
      ]
    , "body":
      { "type": "RESULT"
      , "provides":
        {"type": "env", "vars": ["pkg-config", "PATH", "PKG_CONFIG_PATH"]}
      }
    }
  }
, "system_library":
  { "doc": ["A system library via pkg-config"]
  , "string_fields": ["name", "args", "stage"]
  , "implicit":
    { "defaults": [["./", "..", "defaults"]]
    , "shell defaults": [["shell", "defaults"]]
    , "add_rpath": ["add_rpath"]
    , "pkgconfig defaults": ["defaults"]
    }
  , "config_vars": ["PKG_CONFIG_ARGS", "ENV"]
  , "field_doc":
    { "name": ["The pkg-config name of the library."]
    , "args":
      [ "Additional pkg-config arguments (e.g., \"--define-prefix\" or"
      , "\"--static\"), appended to the config variable \"PKG_CONFIG_ARGS\"."
      ]
    , "stage": ["The stage of the internally created flag files."]
    , "defaults": ["The C/C++ toolchain to use"]
    , "pkgconfig defaults": ["The pkgconfig configuration to use"]
    }
  , "config_doc":
    { "PKG_CONFIG_ARGS":
      [ "Additional pkg-config arguments (e.g., \"--define-prefix\" or"
      , "\"--static\")."
      ]
    , "ENV":
      [ "The environment for any action generated. May contain colon-separated"
      , "\"PKG_CONFIG_PATH\" for looking up pkg-config files; this variable,"
      , "as well as \"PATH\", is prefixed by the values provided in"
      , "the \"defaults\"."
      ]
    }
  , "imports": {"pkgconfig result": "pkgconfig result"}
  , "expression":
    { "type": "let*"
    , "bindings":
      [ [ "name"
        , { "type": "assert_non_empty"
          , "msg": "system_library requires non-empty name"
          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
          }
        ]
      , [ "args"
        , { "type": "++"
          , "$1":
            [ {"type": "var", "name": "PKG_CONFIG_ARGS", "default": []}
            , {"type": "FIELD", "name": "args"}
            ]
          }
        ]
      , [ "stage"
        , { "type": "join"
          , "separator": "/"
          , "$1": {"type": "FIELD", "name": "stage"}
          }
        ]
      ]
    , "body": {"type": "CALL_EXPRESSION", "name": "pkgconfig result"}
    }
  }
}