From: Manish Goregaokar <manishsmail@gmail.com>
Date: Wed, 13 Jan 2016 22:52:20 +0000 (+0530)
Subject: Rollup merge of #30863 - jseyfried:no_rc, r=eddyb
X-Git-Url: https://git.lizzy.rs/?a=commitdiff_plain;h=1246f43bf9d9c21edc65bb6d26fc3ef883dd9f40;p=rust.git

Rollup merge of #30863 - jseyfried:no_rc, r=eddyb

Use arena allocation instead of reference counting for `Module`s to fix memory leaks from `Rc` cycles.

A module references its module children and its import resolutions, and an import resolution references the module defining the imported name, so there is a cycle whenever a module imports something from an ancestor module.

For example,
```rust
mod foo { // `foo` references `bar`.
    fn baz() {}
    mod bar { // `bar` references the import.
        use foo::baz; // The import references `foo`.
    }
}
```
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1246f43bf9d9c21edc65bb6d26fc3ef883dd9f40