Description

c_string() does not validate its argument type. Passing an EZ string literal (or any non-pointer value) bypasses the typechecker and produces a C compilation error:

operand of type 'EzString' where arithmetic or pointer type is required

Users should never see C compiler errors.

Repro

do main() {
    mut msg = c_string("hello")
    println(msg)
}

Expected: Typechecker error — c_string() expects a raw pointer from C interop.

Actual: Falls through to codegen and fails at C compilation.

Root cause

In typechecker.c, c_string is recognized and its return type is set to string, but there's no check that the argument is a pointer type (TK_POINTER). The codegen wraps the EZ string in ez_string_lit() and tries to cast it to const char*, which fails at the C level.

Fix

Add a type check in the typechecker's c_string handler — verify the argument resolves to a pointer type. If not, emit E3083.