qmk/qmk_firmware

[Bug] with two mod tap keys and RETRO_TAPPING, the first tap is ignored

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#11,434 opened on Jan 4, 2021

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Description

I am unsure if this is a bug or expected behaviour. I've managed to simulate the behaviour I wanted with PERMISSIVE_HOLD and fine-tuning TAPPING_TERM to my preference, but nevertheless this surprised me.

Replicating:

  • in config, RETRO_TAPPING activated and TAPPING_TERM set to something low (or zero)
  • layout with two mod tap keys, eg LCTL_T(KC_MINS) and LSFT_T(KC_TAB)
  • hold one mod tap key, eg. LCTL_T
  • tap the other key, eg LSFT_T

What I expected: ctrl+tab is sent.

What happens: nothing is sent on the first tap. From the second tap onwards, the expected behaviour happens. So for whatever reason the first tap is eaten up.

System Information

  • Keyboard: jj40
  • Operating system: linux
  • AVR GCC version: 10.2.0
  • ARM GCC version: 10.2.0
  • QMK Firmware version: 0.11.23
  • Any keyboard related software installed? No, just xkb.

This is the configuration I use: https://github.com/vaaas/dotfiles/tree/master/qmk/jjvas

Contributor guide

Research direction
Investigate the interaction of RETRO TAPPING with multiple mod tap keys; trace the handling of taps when one mod tap is held and another is tapped.
Tech stack
c
Domain
embedded iot
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
CGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60