shugo

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shugo

#!/usr/bin/env ruby
# Heuristic checker for non-volatile locals read on the longjmp path.
#
# Scans C sources for functions using EC_EXEC_TAG()/EXEC_TAG()/RUBY_SETJMP
# and reports locals that are declared before the setjmp, are not volatile,
# and are read in the longjmp-reachable region (outside the TAG_NONE block).
#
# Two severities:
#   STRICT - also written between setjmp and longjmp: indeterminate per
#            C11 7.13.2.1p3, a real portability bug.

shugo

I built a small PEG/packrat parser-combinator gem (packrat_parser) whose grammar rules can be written with a Scala-style for-comprehension. The comprehension is a feature of an experimental Ruby fork: for x in p, y in q then ... end desugars (at parse time) to p.flat_map { |x| q.map { |y| ... } }. Along the way I hit a subtle bug caused by the comprehension's loop variables leaking into the enclosing method scope. This writeup is mostly about that bug.

The comprehension is only recognized by the fork's legacy parser, so everything below runs with ruby --parser=parse.y. The default (Prism) parser rejects for ... then.

shugo

module M
  refine String do
    def shout = upcase + "!"
  end
end

N = 2_000_000
prc = ->(s) { s }

# Warm up the memo

shugo

require "objspace"

module M
  refine String do
    def shout = upcase + "!"
  end
end

module A
  refine(String) { def shout = "A" }

shugo

/home/shugo/.rbenv/shims/ruby --disable=gems -rrubygems -I./benchmark/lib ./benchmark/benchmark-driver/exe/benchmark-driver \
            --executables="compare-ruby::/home/shugo/src/ruby/ruby -I.ext/common --disable-gem" \
            --executables="built-ruby::./miniruby -I./lib -I. -I.ext/common  ./tool/runruby.rb --extout=.ext  -- --disable-gems --disable-gem" \
            --output=markdown --output-compare -v $(find ./benchmark -maxdepth 1 -name 'vm' -o -name '*vm*.yml' -o -name '*vm*.rb' | sort) 
compare-ruby: ruby 4.1.0dev (2026-01-06T04:38:13Z master ad6b85450d) +PRISM [x86_64-linux]
built-ruby: ruby 4.1.0dev (2026-06-09T07:45:27Z feature/proc-with_.. d58b477bf8) +PRISM [x86_64-linux]
warming up...............................................
# Iteration per second (i/s)

|                                     |compare-ruby|built-ruby|

shugo

def hello
  puts "hello"
end

Task.new do
  using PipeOUT
  puts "hello" # パイプに書く
  hello # パイプに書く？
end

shugo

openpgp4fpr:1e565fa7b310cfc1b144d93c2dfe34085e97ce47

shugo

$c=%,$c=%%%%%%%%%c%%%%s%%c;puts$c%%%%%%%%44%%%%%%%%44%%%%%%%%$c,;puts$c%44%44%$c

shugo

def foo
  x = 1
  x
  y
end