[Issue 19939] New: std.format %13,3.2f does not count width correctly

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=19939

          Issue ID: 19939
           Summary: std.format %13,3.2f does not count width correctly
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: phobos
          Assignee: nobody at puremagic.com
          Reporter: hsteoh at quickfur.ath.cx

Example code:
-------
import std.stdio;
void main() {
        writefln("^%13,3.2f$",          1.00);
        writefln("^%13,3.2f$",         10.00);
        writefln("^%13,3.2f$",        100.00);
        writefln("^%13,3.2f$",      1_000.00);
        writefln("^%13,3.2f$",     10_000.00);
        writefln("^%13,3.2f$",    100_000.00);
        writefln("^%13,3.2f$",  1_000_000.00);
        writefln("^%13,3.2f$", 10_000_000.00);
}
-------

Expected output:
-------
^         1.00$
^        10.00$
^       100.00$
^     1,000.00$
^    10,000.00$
^   100,000.00$
^ 1,000,000.00$
^10,000,000.00$
-------

Actual output:
-------
^         1.00$
^        10.00$
^      100.00$
^     1,000.00$
^    10,000.00$
^  100,000.00$
^ 1,000,000.00$
^10,000,000.00$
-------

It seems that there is an off-by-1 error in the reckoning for width when
formatting floating-point values with a format that contains a `,n` flag.

--