Spidermonkey test suite. Don't know yet where the error is, but the unconverted value of s has 1024 at position 0 as expected. I haven't looked into what the code points signify. 15.5.4.11-5 String.prototype.toLowerCase() var s = new String( String.fromCharCode(1024) ); s.toLowerCase().charCodeAt(0) = 1104 FAILED! expected: 1024 var s = new String( String.fromCharCode(1024) ); s.toLowerCase().charCodeAt(0) = 1104 FAILED! expected: 1024 var s = new String( String.fromCharCode(1037) ); s.toLowerCase().charCodeAt(0) = 1117 FAILED! expected: 1037 var s = new String( String.fromCharCode(1037) ); s.toLowerCase().charCodeAt(0) = 1117 FAILED! expected: 1037 FAILED passes:129 fails:2 unexpected passes: 0 expected failures: 0

In related news, the spidermonkey test suite thinks that toUpperCase should behave as toLowerCase does, and vice versa, so (barring errors in the test suite) it looks like simple transposition of values in tables here: 15.5.4.12-1 String.prototype.toUpperCase() var s = new String( String.fromCharCode(1104) ); s.toUpperCase().charCodeAt(0) = 1024 FAILED! expected: 1104 var s = new String( String.fromCharCode(1104) ); s.toUpperCase().charCodeAt(0) = 1024 FAILED! expected: 1104 var s = new String( String.fromCharCode(1117) ); s.toUpperCase().charCodeAt(0) = 1037 FAILED! expected: 1117 var s = new String( String.fromCharCode(1117) ); s.toUpperCase().charCodeAt(0) = 1037 FAILED! expected: 1117 FAILED passes:126 fails:2 unexpected passes: 0 expected failures: 0

Passing to QRB, confirmed issue with rev-2680 var s = new String( String.fromCharCode(1104) ); trace("1104: " + s.toUpperCase().charCodeAt(0)) s = new String( String.fromCharCode(1117) ); trace("1117: " + s.toUpperCase().charCodeAt(0)); s = new String( String.fromCharCode(1024) ); trace("1024: " + s.toLowerCase().charCodeAt(0)); s = new String( String.fromCharCode(1037) ); trace("1037: " + s.toLowerCase().charCodeAt(0 output: 1104: 1024 1117: 1037 1024: 1104 1037: 1117 expected: 1104: 1104 1117: 1117 1024: 1024 1037: 1037

Any fix for this would likely have to be version-checked for backwards compatibility.

Tamarin is a dead project now. Mass WONTFIX.

Tamarin isn't maintained anymore. WONTFIX remaining bugs.