Issues

• Kernel#Integer probes to_str before to_int, so an object defining both converts through the String

  sam-xif/ruby-lean#158 · Filter by author jiro-by-nori opened on Nov 15, 2026

• __conv_callable? treats any user method_missing as serving every name, so String.try_convert/Array/Integer/Float raise NoMethodError where CRuby answers nil

  sam-xif/ruby-lean#152 · Filter by author jiro-by-nori opened on Nov 14, 2026

• Pathname's blanket instance method_missing gates names no Ruby defines, and hides which real method is missing

  sam-xif/ruby-lean#147 · Filter by author jiro-by-nori opened on Nov 12, 2026

• Range#each raises NoMethodError where CRuby raises TypeError "can't iterate from <Class>", and compares with </<= where CRuby compares with <=>

  sam-xif/ruby-lean#144 · Filter by author jiro-by-nori opened on Nov 12, 2026

• A float literal can decode one ulp away from CRuby: ["flt"] goes through Lean's truncating ofScientific

  sam-xif/ruby-lean#141 · Filter by author jiro-by-nori opened on Nov 12, 2026

• Enumerable#take/#drop/#each_slice/#each_cons never convert their count, so a negative size answers and a fractional one is never truncated

  sam-xif/ruby-lean#137 · Filter by author jiro-by-nori opened on Nov 12, 2026

• Array#[]= with a Range subscript raises TypeError instead of splicing

  sam-xif/ruby-lean#133 · Filter by author jiro-by-nori opened on Nov 11, 2026

• String#upcase and #downcase map only ASCII letters, and refuse their selector argument, so non-ASCII case mapping is a wrong answer

  sam-xif/ruby-lean#131 · Filter by author jiro-by-nori opened on Nov 11, 2026

• Enumerable#minmax accepts a comparison block and never calls it, answering the default-comparison pair

  sam-xif/ruby-lean#128 · Filter by author jiro-by-nori opened on Nov 11, 2026

• Dir.exist? answers File.exist?: it is true for a regular file where CRuby answers false

  sam-xif/ruby-lean#125 · Filter by author jiro-by-nori opened on Nov 10, 2026

• A cancelled CI run saves a half-written Lean build, and the next run fails with invalid header instead of rebuilding

  sam-xif/ruby-lean#119 · Filter by author jiro-by-nori opened on Nov 10, 2026
  8

• Enumerable#index is invented, so Range#index answers where CRuby raises NoMethodError

  sam-xif/ruby-lean#116 · Filter by author jiro-by-nori opened on Nov 9, 2026

• Range#count is aliased to #size, so it silently ignores a block and rejects the item argument

  sam-xif/ruby-lean#115 · Filter by author jiro-by-nori opened on Nov 9, 2026

• Range#first answers a wrong-arity ArgumentError for the counted form, and nil for the bare form on a beginless range

  sam-xif/ruby-lean#114 · Filter by author jiro-by-nori opened on Nov 9, 2026

• Range#last(n) raises a wrong-arity ArgumentError instead of gating, unlike Array#last(n) and Range#first(n)

  sam-xif/ruby-lean#110 · Filter by author jiro-by-nori opened on Nov 9, 2026

• Integer#round and Integer#truncate step the wrong way for a negative receiver with a negative count

  sam-xif/ruby-lean#108 · Filter by author jiro-by-nori opened on Nov 9, 2026

• Integer#step rejects its one-argument and keyword forms, and keeps an Integer receiver when an argument is a Float

  sam-xif/ruby-lean#104 · Filter by author jiro-by-nori opened on Nov 9, 2026

• Array#join drops the separator boundary around an empty nested array

  sam-xif/ruby-lean#102 · Filter by author jiro-by-nori opened on Nov 8, 2026

• Pathname.new coerces any argument with to_s instead of using to_path/to_str, so it answers where CRuby raises TypeError

  sam-xif/ruby-lean#93 · Filter by author jiro-by-nori opened on Nov 7, 2026

• Pathname#empty? answers String#empty? instead of asking the filesystem, so it is a wrong answer

  sam-xif/ruby-lean#91 · Filter by author jiro-by-nori opened on Nov 7, 2026

• Split prelude.rb into an organized set of files

  sam-xif/ruby-lean#70 · Filter by author sam-xif opened on Oct 15, 2026

• IO#gets/readline/each_line ignore the global input record separator $/, answering wrong lines

  sam-xif/ruby-lean#64 · Filter by author sam-xif opened on Oct 10, 2026

• File path helpers coerce non-String paths with to_s instead of refusing, so the model answers where CRuby raises TypeError

  bugtech-debt
  sam-xif/ruby-lean#57 · Filter by author sam-xif opened on Oct 10, 2026

• nativeInstanceNames is hand-maintained against a generated source of truth and can drift silently

  sam-xif/ruby-lean#55 · Filter by author sam-xif opened on Oct 10, 2026

• Books/FastPower/Proof.lean pins concrete heap object ids and breaks silently on any boot shift (extends #22)

  sam-xif/ruby-lean#53 · Filter by author sam-xif opened on Oct 10, 2026