COOKED_READ: cmd.exe tab fails to erase trailing characters

[lhecker]

Windows build number

10.0.26052.0

Steps to reproduce

• Launch cmd.exe
• Type foo bar
• Move the cursor the space after foo
• Press tab

Expected Behavior

The prompt reads foo.

Actual Behavior

The prompt reads foo bar and trailing bar is inaccessible.

[lhecker]

No way... This reproduces all the way back to conhost v1 lol. At this point we've found ReadConsole's dwCtrlWakeupMask API:

• overwrote the character under the cursor with the control character even though it wasn't ever intended to do that
• allowed you read beyond the end of the initialized buffer
• assumed that 1 char = 1 column despite being added after the W APIs got added
• ✨NEW✨ doesn't even erase the end of the prompt

At this point I finally got to say: Kudos to the people who designed, implemented and reviewed the CONSOLE_READCONSOLE_CONTROL API. Whoever you all are, all of you did a. fantastic. job.