Bug #20866: Prism assertion when running simplecov with branch coverage and requiring certain code

• Status: Assigned
• Assignee: prism
• Target version: -
• ruby -v: ruby 3.4.0dev (2024-11-05T13:53:41Z master ed06f018bd) +PRISM [x86_64-linux]
• Backport: 3.1: UNKNOWN, 3.2: UNKNOWN, 3.3: UNKNOWN

[Earlopain (Earlopain _)]

I stumbled upon the following bug report against simplecov: https://github.com/simplecov-ruby/simplecov/issues/1113

I reduced the error down to the following:

# Gemfile
source "https://rubygems.org"

gem "simplecov"

# test.rb
require "bundler"
require "simplecov"

SimpleCov.start do
  enable_coverage :branch
end

require_relative "external"

# external.rb
def perform_completion
  case @completion_state
  when CompletionState::PERFECT_MATCH
    @dig_perfect_match_proc&.(@perfect_matched)
  end
end

$ bundle exec ruby test.rb
ruby: prism/util/pm_newline_list.c:93: pm_newline_list_line_column: Assertion `cursor >= list->start' failed.
Aborted (core dumped)

When running with parse.y the error doesn't occur.

[alanwu (Alan Wu)]

• Assignee set to prism

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Assigned

[eightbitraptor (Matt V-H)]

This was caused by an issue with how the prism compiler tracks the ending location of call nodes of the form a&.().

Should be fixed by this PR