On the emscripten mailing list we got a report that using %lf as a format specifier for doubles worked in printf but not wprintf, which I was able to confirm looking at the musl implementation we're using.

It looks like support for %lf in printf was added in 2012 in commit cc3a44666, but didn't get copied to the wprintf implementation so they're just out of sync. I've attached a small patch which copies the same fix to the wprintf side.

Please let me know if there's any test cases I should add to, or anything else. Thanks!

-- brion