src/test/compile-fail/mutable-huh-variance-vec4.rs


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fn main() {

    // Note: here we do not have any type annotations
    // but we do express conflicting requirements:

    let v = [mut [0]];
    let w = [mut [mut 0]];
    let x = [mut [mut 0]];

    fn f(&&v: [mut [int]]) {
        v[0] = [3]
    }

    fn g(&&v: [const [const int]]) {
    }

    fn h(&&v: [mut [mut int]]) {
        v[0] = [mut 3]
    }

    fn i(&&v: [mut [const int]]) {
        v[0] = [mut 3]
    }

    fn j(&&v: [[const int]]) {
    }

    f(v);
    g(v);
    h(v); //! ERROR (values differ in mutability)
    i(v); //! ERROR (values differ in mutability)
    j(v); //! ERROR (values differ in mutability)

    f(w); //! ERROR (values differ in mutability)
    g(w);
    h(w);
    i(w); //! ERROR (values differ in mutability)
    j(w); //! ERROR (values differ in mutability)

    // Note that without adding f() or h() to the mix, it is valid for
    // x to have the type [mut [const int]], and thus we can safely
    // call g() and i() but not j():
    g(x);
    i(x);
    j(x); //! ERROR (values differ in mutability)
}