rust/compiler/rustc_passes
bors 9556d7a09a Auto merge of #88337 - eddyb:field-failure-is-not-an-option, r=nagisa
rustc_target: `TyAndLayout::field` should never error.

This refactor (making `TyAndLayout::field` return `TyAndLayout` without any `Result` around it) is based on a simple observation, regarding `TyAndLayout::field`:

If `cx.layout_of(ty)` succeeds (for some `cx` and `ty`), then `.field(cx, i)` on the resulting `TyAndLayout` should *always* succeed in computing `cx.layout_of(field_ty)` (where `field_ty` is the type of the `i`th field of `ty`).

The reason for this is that no matter which field is chosen, `cx.layout_of(field_ty)` *will have already been computed*, as part of computing `cx.layout_of(ty)`, as we cannot determine the layout of *any* type without considering the layouts of *all* of its fields.

And so it should be fine to turn any errors into ICEs, since they likely indicate a `cx` mismatch, or some other edge case that is due to a compiler bug (as opposed to ever being an user-facing error).

<hr/>

Each commit should probably be reviewed separately, though note that there's some `where` clauses (in `rustc_target::abi::call::*`) that change in most commits.

cc `@nagisa` `@oli-obk`
2021-08-29 22:54:26 +00:00
..
src Auto merge of #88337 - eddyb:field-failure-is-not-an-option, r=nagisa 2021-08-29 22:54:26 +00:00
Cargo.toml Remove Session.used_attrs and move logic to CheckAttrVisitor 2021-08-21 13:27:27 -05:00