0dcde02cc7
Given code like `v[&field].boo();` where `field: String` and `.boo(&mut self)`, typeck will have decided that `v` is accessed using `Index`, but when `boo` adds a new `mut` obligation, `convert_place_op_to_mutable` is called. When this happens, for *some reason* the arguments' dereference adjustments are completely ignored causing an error saying that `IndexMut` is not satisfied: ``` error[E0596]: cannot borrow data in an index of `Indexable` as mutable --> src/main.rs:30:5 | 30 | v[&field].boo(); | ^^^^^^^^^ cannot borrow as mutable | = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `Indexable` ``` This is not true, but by changing `try_overloaded_place_op` to retry when given `Needs::MutPlace` without passing the argument types, the example successfully compiles. I believe there might be more appropriate ways to deal with this.
29 lines
503 B
Rust
29 lines
503 B
Rust
// check-pass
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struct Indexable;
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impl Indexable {
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fn boo(&mut self) {}
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}
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impl std::ops::Index<&str> for Indexable {
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type Output = Indexable;
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fn index(&self, field: &str) -> &Indexable {
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self
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}
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}
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impl std::ops::IndexMut<&str> for Indexable {
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fn index_mut(&mut self, field: &str) -> &mut Indexable {
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self
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}
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}
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fn main() {
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let mut v = Indexable;
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let field = "hello".to_string();
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v[field.as_str()].boo();
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v[&field].boo(); // < This should work
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}
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