Modifications to mutable slices affect non-mut arrays

[uinz]

Describe the bug

Non-mut variables should not be modified

Expected Behavior

cannot declare a mut slice from a non-mut array

Current Behavior

Modifications to mutable slices affect non-mut arrays

Reproduction Steps

module main

fn main() {
	xs := [1, 2, 3, 4, 5, 6, 7, 8]

	mut s := xs[1..]

	s.sort(a > b)

	println(xs) // [1, 8, 7, 6, 5, 4, 3, 2]
}

Possible Solution

No response

Additional Information/Context

No response

V version

V 0.4.0 3c26bff

Environment details (OS name and version, etc.)

V full version: V 0.4.0 4cf8328.3c26bff
OS: macos, macOS, 13.4.1, 22F82
Processor: 10 cpus, 64bit, little endian, Apple M1 Pro

getwd: /Users/xxx/Desktop/test_v
vexe: /opt/homebrew/Cellar/vlang/0.4/libexec/v
vexe mtime: 2023-08-12 00:33:32

vroot: OK, value: /opt/homebrew/Cellar/vlang/0.4/libexec
VMODULES: OK, value: /Users/xxx/.vmodules
VTMP: OK, value: /tmp/v_501

Git version: git version 2.39.2 (Apple Git-143)
Git vroot status: weekly.2023.31-43-g3c26bfff
.git/config present: true

CC version: Apple clang version 14.0.3 (clang-1403.0.22.14.1)
thirdparty/tcc status: thirdparty-macos-arm64 a668e5a0