github-linguist/linguist · warning · NotImplementedError

current_tree is deprecated

Error message

current_tree is deprecated

What it means

current_tree is the second legacy Rugged-specific helper on Linguist::Repository: it returns the commit's tree via repository.get_tree, but raises NotImplementedError ('current_tree is deprecated') whenever the injected source is not a Linguist::Source::RuggedRepository. As with read_index, the constructor only wraps raw Rugged repos; an injected custom Source::Repository leaves this path unavailable. The tree is an internal detail of stats computation — callers should use #language_stats/#cache rather than walking the tree themselves.

Source

Thrown at lib/linguist/repository.rb:137

    #
    # Returns a map of filename => [language, size]
    def cache
      @cache ||= begin
        if @old_commit_oid == @commit_oid
          @old_stats
        else
          compute_stats(@old_commit_oid, @old_stats)
        end
      end
    end

    def read_index
      raise NotImplementedError, "read_index is deprecated" unless repository.is_a? Linguist::Source::RuggedRepository
      repository.set_attribute_source(@commit_oid)
    end

    def current_tree
      raise NotImplementedError, "current_tree is deprecated" unless repository.is_a? Linguist::Source::RuggedRepository
      repository.get_tree(@commit_oid)
    end

    protected
    def compute_stats(old_commit_oid, cache = nil)
      return {} if repository.get_tree_size(@commit_oid, @max_tree_size) >= @max_tree_size

      repository.set_attribute_source(@commit_oid)
      diff = repository.diff(old_commit_oid, @commit_oid)

      # Clear file map and fetch full diff if any .gitattributes files are changed
      if cache && diff.each_delta.any? { |delta| File.basename(delta.new_file[:path]) == ".gitattributes" }
        diff = repository.diff(nil, @commit_oid)
        file_map = {}
      else
        file_map = cache ? cache.dup : {}
      end

View on GitHub (pinned to b45dbe9b28)

Solutions

1. Use the public API: `repo.language_stats` returns the language breakdown without needing the tree.
2. If you must enumerate entries, add an equivalent accessor to your custom source class and call it on `repo.repository` directly.
3. Gate legacy usage: `tree = repo.current_tree if repo.repository.is_a?(Linguist::Source::RuggedRepository)`.
4. Delete references to current_tree when upgrading — it is explicitly marked deprecated and will not be extended to other sources.

Example fix

# before
linguist_repo.current_tree.each_blob { |b| analyze(b) }

# after
stats = linguist_repo.language_stats # { "Ruby" => 1234, ... }

def tree_via_source(linguist_repo)
  src = linguist_repo.repository
  return src.get_tree(linguist_repo.instance_variable_get(:@commit_oid)) if src.is_a?(Linguist::Source::RuggedRepository)
  src.respond_to?(:get_tree) ? src.get_tree : nil
end

def rugged_backed?(linguist_repo)
  linguist_repo.repository.is_a?(Linguist::Source::RuggedRepository)
end

begin
  tree = linguist_repo.current_tree
rescue NotImplementedError => e
  raise unless e.message =~ /current_tree is deprecated/
  tree = nil # fall back to language_stats for whatever you needed the tree for
end

When it happens

Trigger: 1) Calling `repo.current_tree` on a Repository built around a custom Linguist::Source::Repository implementation. 2) Code ported from older linguist versions that used current_tree to enumerate blobs for analysis. 3) Specs with fake/stub sources (not RuggedRepository instances) exercising old helper calls.

Common situations: Version upgrades from pre-source-abstraction linguist to 5.x+ where internal helpers now guard on the source type; hosting applications injecting their own source adapter; scripts that enumerated `current_tree` blobs directly instead of using the stats API.

Related errors

• read_index is deprecated
• Duplicate language name: #{language.name}
• Duplicate language name: #{language.fs_name}
• Duplicate alias: #{name}
• Extension is missing a '.': #{extension.inspect}

AI-assisted analysis of github-linguist/linguist@b45dbe9b28 (2026-08-21). Data as JSON: /api/errors/d0ffc1382f2b8628. Report an issue: GitHub.