_diff: insulate line-reading from caller's $/ - #2
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_diff reads the diff subprocess's output line-by-line via <$stdout>, which implicitly relies on the caller not having changed $/. If a caller left $/ set to undef (slurp mode) or another non-default value - for example via an improperly scoped `local $/;` earlier in the same process - reading an already-at-EOF pipe returns an empty string once instead of undef immediately. That phantom empty "line" was treated as a real line of diff output, producing a false failure for two JSON documents that are actually the same. Found while integrating this module into a large test suite where an unrelated script had left $/ globally altered. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
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_diff reads the diff subprocess's output line-by-line via <$stdout>, which implicitly relies on the caller not having changed$/. If a caller left $ / set to undef (slurp mode) or another non-default value
local $/;earlier in the same process - reading an already-at-EOF pipe returns an empty string once instead of undef immediately. That phantom empty "line" was treated as a real line of diff output, producing a false failure for two JSON documents that are actually the same.Found while integrating this module into a large test suite where an unrelated script had left $/ globally altered.