Return type arrow syntax error on negative values

[2colours]

The Problem

The return type arrow can take constants as the return value of the function, including decimal fractions: however the parsing fails on the unary minus of negative numbers.

Expected Behavior

sub f(--> -1) {}
should compile, with f returning -1.

Actual Behavior

The following error message is shown:
===SORRY!=== Error while compiling:
Malformed return value
------> sub f(-->⏏ -1) {}

Steps to Reproduce

Define any function with a negative numeric literal as the arrow return value, as opposed to its positive counterpart.

Environment

• Operating system: 5.4.0-47-generic 51-Ubuntu SMP Fri Sep 4 19:50:52 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
• Compiler version (perl6 -v or raku -v): Welcome to Rakudo™ v2021.12. Implementing the Raku® Programming Language v6.d. Built on MoarVM version 2021.12.