Fix breaking references after GC.compact#2822
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ksss merged 2 commits intoruby:masterfrom Jan 23, 2026
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I found that even static symbols can have broken references starting from 4.0, so I fixed it to copy uniquely. |
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Jan 30, 2026
If GC.compact occurs after parsing, strings referenced from the parse result are corrupted.
Below is a reproduction script.
In this case, it is intentionally reproducing a scenario where `GC.compact` occurs during parsing.
```rb
require 'rbs'
module Patch
def to_i(...)
super(...)
end
end
String.prepend(Patch)
TracePoint.new(:call) do |tp|
GC.start
GC.start
GC.compact
end.enable(target: String.instance_method(:to_i))
errors = 0
n = 100
n.times do |i|
1000.times { |i| "\x00" * (1000); "X#{i}" * 100 }
len = 500
var = ("A" * len + "_V#{i}").to_sym
type = "(42 | #{var}) -> Array[#{var}]"
result = RBS::Parser.parse_method_type(type, variables: [var])
if var == result.type.return_type.args.first.name
print "."
else
errors += 1
print "X"
end
end
puts "\n#{errors}/n errors (#{(errors * 100.0 / n).round(1)}%)"
exit(errors > 0 ? 1 : 0)
```
To fix this issue, similar to ruby#2822 ,
strings of symbols given as arguments are copied and retained.
If it is an **owned** type, `free()` will also be performed when the constant pool is freed.
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Although rare, there's a possibility of breaking references after
GC.compactif a dynamic symbol happens to be interned into the constant pool.To fix this issue, I've modified the code to copy the string and intern it as an owned type when a dynamic symbol is passed.
Additionally, we've written a test case that reproduces the problem.