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mruby-regexp: read the real type of String#split's limit #7004

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Merged
matz merged 1 commit into from
Aug 3, 2026
Merged

mruby-regexp: read the real type of String#split's limit #7004

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5 changes: 4 additions & 1 deletion mrbgems/mruby-regexp/mrblib/string_regexp.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -138,7 +138,10 @@ def split(pattern = nil, *args)
# `ary[obj]` and `"s" * obj` all reject an object that only defines
# `to_int`; dispatching it here would leave this the one place in the tree
# that accepts one, as the same reasoning keeps `match` off `to_str`.
if limit_given && !limit.is_a?(Integer)
# `is_a?` is redefinable, so a limit claiming to be an Integer would skip
# that conversion and reach the arithmetic below as itself. `Module#===`
# reads the real type and cannot be redefined.
if limit_given && !(Integer === limit)
limit = limit.__to_int
end
# `nil?` and `is_a?` are redefinable, so an argument answering either one
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38 changes: 38 additions & 0 deletions mrbgems/mruby-regexp/test/regexp.rb
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Expand Up @@ -1082,6 +1082,44 @@ def limit.respond_to?(name, include_all = false); true; end
assert_raise(TypeError) { "a,b".split(/,/, limit) }
end

class StringSplitLimitIsALiar
def is_a?(klass)
true
end
end

class StringSplitLimitComparable
def is_a?(klass)
true
end

def ==(other)
false
end

def >(other)
true
end

def -(other)
1
end
end

assert("String#split limit cannot pose as an Integer") do
# `is_a?` is redefinable, so a limit claiming to be an Integer used to skip
# the conversion and reach the split loop as itself.
assert_raise(TypeError) { "a,b,c".split(/,/, StringSplitLimitIsALiar.new) }
# The String pattern delegates to __split, which converts the limit again in
# C, so this one held before the fix too. Asserted so that the two halves of
# the method stay pinned to the same answer.
assert_raise(TypeError) { "a,b,c".split(",", StringSplitLimitIsALiar.new) }

# Answering the operators the loop uses used to produce a wrong result
# instead of an error.
assert_raise(TypeError) { "a,b,c".split(/,/, StringSplitLimitComparable.new) }
end

assert("String#split with empty regexp") do
assert_equal ["a", "b", "c"], "abc".split(//)
assert_equal ["a", "bc"], "abc".split(//, 2)
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