Comptime reflection compares all field values as strings.

[katekyy]

Describe the bug

As said in the title, compile time reflection compares all field values as strings.
Looking at the generated C code:

if (!string__eq(_v_new.ButtonStyleParams, _v_default.ButtonStyleParams)) {
	old->ButtonStyleParams = _v_new.ButtonStyleParams;
}

Reproduction Steps

struct Abc {
	id int
	name string
	letter string
}

fn join[T](mut old T, new T) {
	$if T is $struct {
		default := T{}
		$for field in T.fields {
			if new.$(field.name) != default.$(field.name) {
				old.$(field.name) = new.$(field.name)
			}
		}
	}
}

fn main() {
	mut a := Abc{name: 'Peter', letter: 'a'}
	b := Abc{id: 1, letter: 'b'}
	join(mut a, b)

	assert a == Abc{name: 'Peter', id: 1, letter: 'b'}
}

Expected Behavior

Output:

Abc{
    id: 1
    name: 'Peter'
    letter: 'b'
}

Current Behavior

==================
/tmp/v_1000/zest_launcher.tmp.c:76124: warning: assignment from incompatible pointer type
/tmp/v_1000/zest_launcher.tmp.c:91043: error: cannot convert 'struct ui__ButtonStyleParams' to 'struct string'
...
==================
(Use `v -cg` to print the entire error message)

builder error: 
==================
C error. This should never happen.

This is a compiler bug, please report it using `v bug file.v`.

https://github.com/vlang/v/issues/new/choose

You can also use #help on Discord: https://discord.gg/vlang

Possible Solution

No response

Additional Information/Context

No response

V version

0.4.2 8f76a06

Environment details (OS name and version, etc.)

V full version: V 0.4.2 8f76a06
OS: linux, Linux version 6.1.52-1-lts (linux-lts@archlinux) (gcc (GCC) 13.2.1 20230801, GNU ld (GNU Binutils) 2.41.0) #1 SMP PREEMPT_DYNAMIC Thu, 07 Sep 2023 05:17:41 +0000
Processor: 8 cpus, 64bit, little endian, 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz

getwd: /home/katekyy/programming/zest_launcher
vexe: /home/katekyy/.local/share/v/v
vexe mtime: 2023-10-14 18:01:00

vroot: OK, value: /home/katekyy/.local/share/v
VMODULES: OK, value: /home/katekyy/.vmodules
VTMP: OK, value: /tmp/v_1000

Git version: git version 2.42.0
Git vroot status: weekly.2023.33-352-g8f76a062
.git/config present: true

CC version: cc (GCC) 13.2.1 20230801
thirdparty/tcc status: thirdparty-linux-amd64 12f392c3

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