new compiler: private struct fields of another module can be read

[davlgd]

Describe the bug

The new compiler lets a module read a private field of a struct declared in another module. The old compiler rejects it, as expected.

Reproduction Steps

lib/lib.v:

module lib

pub struct Box {
mut:
	secret int
}

pub fn new_box() Box {
	return Box{
		secret: 42
	}
}

main.v:

import lib

fn main() {
	b := lib.new_box()
	println(b.secret)
}

v -new-compiler run main.v

Expected Behavior

The error the old compiler gives:

main.v:5:12: error: field `lib.Box.secret` is not public

Current Behavior

It compiles and prints 42.

V version

V 0.5.2 4af2cb4 (-new-compiler). The old compiler I compare with is what -old-compiler runs, the V 0.5.2 release (7647ce1).

Environment details (OS name and version, etc.)

macOS 26.6, arm64, Apple clang 21

Note

You can use the 👍 reaction to increase the issue's priority for developers.

Please note that only the 👍 reaction to the issue itself counts as a vote.
Other reactions and those to comments will not be taken into account.