Bug 18205 – Format string with width specification doesn't work with multibyte characters

--- import std.format; void main() { assert("|%8s|".format("abc") == "| abc|"); assert("|%8s|".format("αβγ") == "| αβγ|"); // FAILS! -> | αβγ| } ---

The current behaviour seems to be by design, according to this unittest assert from Phobos (std.format#L5779): assert(format("%8s", "b\u00e9ll\u00f4") == " b\u00e9ll\u00f4"); The length of the tested string is 8 (code points), but it prints 6 glyphs. I can't guess the rationale behind this, since the purpose is formatting.

Actually the fix is quite easy and obvious. I reopen pull https://github.com/dlang/phobos/pull/6008 And let's see what will the reviewers think.

*** This issue has been marked as a duplicate of issue 7054 ***

This is a long-standing issue that has been known for a while now. It's not so easy to fix because the correct behaviour depends on byGrapheme, but the last time I checked, that breaks @safety and CTFE-ability.