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65de5d0472
Mention that type parameters are used recursively on bivariance error Right now when a type parameter is used recursively, even with indirection (so it has a finite size) we say that the type parameter is unused: ``` struct B<T>(Box<B<T>>); ``` This is confusing, because the type parameter is *used*, it just doesn't have its variance constrained. This PR tweaks that message to mention that it must be used *non-recursively*. Not sure if we should actually mention "variance" here, but also I'd somewhat prefer we don't keep the power users in the dark w.r.t the real underlying issue, which is that the variance isn't constrained. That technical detail is reserved for a note, though. cc `@fee1-dead` Fixes #118976 Fixes #26283 Fixes #53191 Fixes #105740 Fixes #110466 |
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Cargo.toml | ||
messages.ftl | ||
README.md |
For high-level intro to how type checking works in rustc, see the type checking chapter of the rustc dev guide.