On Mon, 5 Oct 2026 15:42:03 GMT, Arnt Gulbrandsen <[email protected]> wrote:
> `java.net.IDN` still implements IDNA2003, which is frozen at Unicode 3.2. > This PR moves it to UTS46 (IDNA2008 with the Unicode compatibility mapping), > which is what the big three browsers and most other languages' IDN libraries > use. > > Names such as faß.de have been registrable since 2010, and today `IDN` turns > that into fass.de, which is a different domain. > > ### Changes > > The implementation is ICU4J's UTS46 code, merged into `jdk.internal.icu` with > the smallest reasonable diff. The UTS46 data (`uts46.nrm`) is generated from > Unicode 17, the same version as `Character`, so `IDN` can follow future > Unicode upgrades instead of being stuck at 3.2. > > This patch removes the IDNA2003 code and its data file, > `sun/net/idn/uidna.spp`,and does not merge the ICU code that only registries > need. > > I also fixed a typo in ICU's `Punycode.isBasicUpperCase()`. > > There are three new public constants: > > - `CHECK_CONTEXTJ` rejects ZWJ/ZWNJ (U+200D, U+200C) in contexts where > RFC5892 doesn't allow them. > - `NONTRANSITIONAL_TO_ASCII` maps ß, ς, ZWJ and ZWNJ to themselves rather > than to ss, σ and nothing. This is what registries and browsers do now. > - `NONTRANSITIONAL_TO_UNICODE` is the same, for `toUnicode()`. > > `ALLOW_UNASSIGNED` is kept for source compatibility but ignored, since UTS46 > knows the whole Unicode repertoire of the running JVM. > > The one-argument `toASCII()` and `toUnicode()` now use > `CHECK_CONTEXTJ|NONTRANSITIONAL_TO_…`. Before, they used no flags. > > ### Behaviour, before and after > > Here are the results from JDK 27 and from this branch. > > | Input | Call | JDK 27 | This PR | > |---|---|---|---| > | grå.org | `toASCII(s)` | xn--gr-zia.org | xn--gr-zia.org | > | 例子.中国 | `toASCII(s)` | xn--fsqu00a.xn--fiqs8s | xn--fsqu00a.xn--fiqs8s | > | faß.de | `toASCII(s)` | fass.de | xn--fa-hia.de | > | faß.de | `toASCII(s, 0)` | fass.de | fass.de | > | GRÅ.ORG | `toASCII(s)` | xn--gr-zia.ORG | xn--gr-zia.org | > | a<U+200D>b.example.com | `toASCII(s)` | ab.example.com | > IllegalArgumentException | > | *.example.com | `toASCII(s)` | *.example.com | *.example.com | > | *.example.com | `toASCII(s, USE_STD3_ASCII_RULES)` | > IllegalArgumentException | IllegalArgumentException | > | ab--cd.example.com | `toASCII(s)` | ab--cd.example.com | ab--cd.example.com > | > | xn--fa-hia.de | `toUnicode(s)` | xn--fa-hia.de | faß.de | > > `toUnicode()` still never throws. It returns any label it can't convert > unchanged, as before. > > UTS46 considers labels with `--` in the third and fourth positions as errors. > `IDN` deliberately ignore... If you don't have JBS access then you'll need a sponsor/buddy to help. First things first would be to try to get someone to help review what you propose. ------------- PR Comment: https://git.openjdk.org/jdk/pull/33210#issuecomment-6500594359
