Bug 18714 – Phobos calls localtime, which is not threadsafe

To implement timezone handling, std.datetime.timezone calls localtime. localtime returns a pointer to a global shared struct. This means that subsequent calls to localtime in a second thread may overwrite the data of the first thread before the first thread can read it, causing corruption. This can be seen by calling localtime on two different arguments in a loop, in two threads, and validating the result.

Commit pushed to master at https://github.com/dlang/phobos https://github.com/dlang/phobos/commit/5d6bf2bdd2fac4ba5da71893d50306963326eedb Do not call localtime. It is not threadsafe. You will randomly return wrong times in threaded apps. Fixes Issue 18714.