ADR 0082: A bare modifier must not clear a pending count¶

Status¶

Accepted

Context¶

10G went to the last line instead of line ten. So did 3D, 2C, 5X — every counted command whose letter needs Shift.

The count was being typed correctly and then thrown away before the letter arrived. Traced by printing the key, its text and m_vimCount1 on every keyPressEvent:

key=0x31 ('1')        text=49   count1=0    -> 1
key=0x30 ('0')        text=48   count1=1    -> 10
key=0x1000020 (Shift) text=0    count1=10
key=0x47 ('G')        mods=Shift count1=0   <- gone

Decision¶

Reject the key on its character, not on emptiness¶

A bare Shift press arrives with an event->text() of one NUL character. That is not empty, so it passed the text.isEmpty() guard at the top of the Vim dispatcher, matched no case anywhere below, and fell through to the resetVimPendingState() that ends the Normal-mode dispatch — which is exactly what a half-typed count lives in.

The guard now rejects a null character as well as an empty string.

This is the same trap as Return¶

ADR 0076 recorded that Return arrives as U+0000 under the offscreen platform plugin and as "\r" under X11, and that r therefore has to branch on the key code. This is the same quirk reaching a different place: event->text() is not a reliable way to ask whether a key carries a character.

That makes two bugs from one cause. Anything testing a key for "is this typed input" should test the character, and anything distinguishing Return, Tab or Escape from typed input should use the key code.

Consequences¶

The screenshot battery had been encoding the bug as expected behaviour since it was written: its 3G step recorded a jump to line 829 of an 828-line file. Five of its twenty-two screens changed when this was fixed, and the change is the fix. A regression suite is only as honest as the behaviour it was captured against.

Whether the bug reproduces under X11 was not tested — Qt may report an empty text there rather than a NUL. It does not matter much: the guard is correct either way, and a bare modifier is never a command.