[fix] Encoding.compatible?: check when swapping args#9345
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headius merged 1 commit intojruby:jruby-10.0from Mar 31, 2026
Merged
[fix] Encoding.compatible?: check when swapping args#9345headius merged 1 commit intojruby:jruby-10.0from
headius merged 1 commit intojruby:jruby-10.0from
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When the first argument is not a String (e.g. Regexp) and the second is, areCompatible check swaps objects so that String is first. However, JRuby also swapped encoding values, which is wrong — CRuby's enc_compatible_latter (encoding.c) only swaps the object/isstr/idx references but keeps enc1/enc2 derived from the original idx values before the swap, so they retain the original argument order. This caused Encoding.compatible?(regexp_eucjp, string_utf8) to return EUC-JP instead of UTF-8 when the string was ASCII-only.
headius
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Mar 31, 2026
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When the first argument is not a String (e.g. Regexp) and the second is, areCompatible check swaps objects so that String is first.
However, JRuby also swapped encoding values, which is wrong — CRuby's enc_compatible_latter (encoding.c) only swaps the object/isstr/idx references but keeps enc1/enc2 derived from the original idx values before the swap, so they retain the original argument order.
This caused
Encoding.compatible?(regexp_eucjp, string_utf8)to returnEUC-JPinstead ofUTF-8when the string was ASCII-only.