Handling Missing Numbers in ANSI Escape Sequences

[GaryDYelle]

• Your Windows build number: (Type ver at a Windows Command Prompt)

Microsoft Windows [Version 10.0.16299.125]

• What you're doing and what's happening: (Copy & paste specific commands and their output, or include screen shots)

test@PC2:~$ printf "\033[31mtest\n"
test (red)
test@PC2:~$ printf "\033[31;mtest\n"
test (red)
test@PC2:~$ printf "\033[31;0mtest\n"
test (white)
test@PC2:~$

• What's wrong
  The second output is printed in red:

• What should be happening instead:

The second output should be printed in white like on Linux:

According to Wikipedia (https://en.wikipedia.org/wiki/ANSI_escape_code):

All common sequences just use the parameters as a series of semicolon-separated numbers such as 1;2;3. Missing numbers are treated as 0 (1;;3 acts like the middle number is 0, and no parameters at all in ESC[m acts like a 0 reset code).

Further details are available from:
https://superuser.com/questions/1280903/how-to-enable-colors-with-win32-openssh-and-putty

[zadjii-msft]

That's a good find! looks like we were treating empty args in the SGR sequences differently. I'll file a bug to handle this, likely sometime in the next release

[zadjii-msft]

Checked in the fix this morning. Should be out to insiders in the next few weeks :)

[DHowett-MSFT]

It looks like this went out with 1809. Thanks for reporting it!