Use of tap_code_delay being described as 'implicit declaration'

[CrisHale]

I've used the tap_code_delay function to try to resolve an issue where setting up the KC_MNXT keycode with a leader key is resulting in sticky behaviour - which I assume is down to the key not unregistering properly - and I'm being told by the compiler (or at least the command line of this MSYS software) that the function is being implicitly declared.

System Information

• Keyboard: Plaid
  • Revision (if applicable):
• Operating system: Windows 10
• AVR GCC version: 8.3.0
• ARM GCC version: 8.3.1 20190703
• QMK Firmware version: fatal: not a git repository (or any of the parent directories): .git (Yes, I know this isn't actually a version, but I don't know what to do about it)
• Any keyboard related software installed?
  • [ ] AutoHotKey
  • [ ] Karabiner
  • [ ] Other:

Additional Context

[zvecr]

With no git version to reference, and being unable to reproduce, closing.