Rollup of 8 pull requests #67246
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Rollup of 8 pull requests #67246
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This officializes what was only shown as a code example in [the unsafe code guidelines](https://rust-lang.github.io/unsafe-code-guidelines/layout/function-pointers.html?highlight=box#use) and follows [the discussion](rust-lang/unsafe-code-guidelines#157) in the corresponding repository. It is also related to [the issue](rust-lang#52976) regarding marking `Box<T>` `#[repr(transparent)]`.
- Use meaningful names - Clarify comments - Fix C function declaration
Co-Authored-By: lzutao <[email protected]>
Currently, the type `struct S { x: u32, y: u32, tag: () }` is
incorrectly described like this:
```
print-type-size type: `S`: 8 bytes, alignment: 4 bytes
print-type-size field `.x`: 4 bytes
print-type-size field `.tag`: 0 bytes, offset: 0 bytes, alignment: 1 bytes
print-type-size padding: 4 bytes
print-type-size field `.y`: 4 bytes, alignment: 4 bytes
```
Specifically:
- The `padding` line is wrong. (There is no padding.)
- The `offset` and `alignment` on the `.tag` line shouldn't be printed.
The problem is that multiple fields can end up with the same offset, and
the printing code doesn't handle this correctly.
This commit fixes it by adjusting the field sorting so that zero-sized fields
are dealt with before non-zero-sized fields. With that in place, the
printing code works correctly.
The commit also corrects the "something is very wrong" comment.
The new output looks like this:
```
print-type-size type: `S`: 8 bytes, alignment: 4 bytes
print-type-size field `.tag`: 0 bytes
print-type-size field `.x`: 4 bytes
print-type-size field `.y`: 4 bytes
```
Clarify `Box<T>` representation and its use in FFI This officializes what was only shown as a code example in [the unsafe code guidelines](https://rust-lang.github.io/unsafe-code-guidelines/layout/function-pointers.html?highlight=box#use) and follows [the discussion](rust-lang/unsafe-code-guidelines#157) in the corresponding repository. It is also related to [the issue](rust-lang#52976) regarding marking `Box<T>` `#[repr(transparent)]`. If the statement this PR adds is incorrect or a more in-depth discussion is warranted, I apologize. Should it be the case, the example in the unsafe code guidelines should be amended and some document should make it clear that it is not sound/supported.
…bank Fix `unused_parens` triggers on macro by example code Fix rust-lang#66295 Unfortunately this does also break [an existing test](https://github.com/rust-lang/rust/blob/4787e97475de6be9487e3d9255a9c2d3c0bf9252/src/test/ui/lint/issue-47775-nested-macro-unnecessary-parens-arg.rs#L22). I'm not sure how to handle that, because that seems to be quite similar to the allowed cases If this gets accepted it would be great to backport this fix to beta.
…ro-sized-fields, r=pnkfelix
Fix `-Z print-type-sizes`'s handling of zero-sized fields.
Currently, the type `struct S { x: u32, y: u32, tag: () }` is
incorrectly described like this:
```
print-type-size type: `S`: 8 bytes, alignment: 4 bytes
print-type-size field `.x`: 4 bytes
print-type-size field `.tag`: 0 bytes, offset: 0 bytes, alignment: 1 bytes
print-type-size padding: 4 bytes
print-type-size field `.y`: 4 bytes, alignment: 4 bytes
```
Specifically:
- The `padding` line is wrong. (There is no padding.)
- The `offset` and `alignment` on the `.tag` line shouldn't be printed.
The problem is that multiple fields can end up with the same offset, and
the printing code doesn't handle this correctly.
This commit fixes it by adjusting the field sorting so that zero-sized fields
are dealt with before non-zero-sized fields. With that in place, the
printing code works correctly.
The commit also corrects the "something is very wrong" comment.
The new output looks like this:
```
print-type-size type: `S`: 8 bytes, alignment: 4 bytes
print-type-size field `.tag`: 0 bytes
print-type-size field `.x`: 4 bytes
print-type-size field `.y`: 4 bytes
```
r? @pnkfelix
… r=Dylan-DPC Remove irelevant comment on `register_dtor` Fixes rust-lang#66572.
resolve: Always resolve visibilities on impl items Fixes rust-lang#64705. Similarly to rust-lang#67106 this was an issue with visitor discipline. Impl items were visited as a part of visiting `ast::ItemKind::Impl`, but they should be visit-able in isolation from their parents as well, because that's how they are visited when they are expanded from macros. I've checked that all the remaining `resolve_visibility` calls are used correctly. r? @matthewjasper
Some small readability improvements
Small std::borrow::Cow improvements This is a small set of improvements (+ one more tested code path) for `Cow`.
…r=Mark-Simulacrum Make TinyList::remove iterate instead of recurse Most of the diff is from from rustfmt, the actual change is in line 91..79 (or 79..89 in the "after" diff). I had converted the other methods to iterate instead of recurse already, so this is the last recursive function on `TinyList`.
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@bors r+ p=8 rollup=never |
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📌 Commit 685d4cc has been approved by |
bors
added a commit
that referenced
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Dec 12, 2019
Rollup of 8 pull requests Successful merges: - #62514 (Clarify `Box<T>` representation and its use in FFI) - #66983 (Fix `unused_parens` triggers on macro by example code) - #67215 (Fix `-Z print-type-sizes`'s handling of zero-sized fields.) - #67230 (Remove irelevant comment on `register_dtor`) - #67236 (resolve: Always resolve visibilities on impl items) - #67237 (Some small readability improvements) - #67238 (Small std::borrow::Cow improvements) - #67239 (Make TinyList::remove iterate instead of recurse) Failed merges: r? @ghost
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☀️ Test successful - checks-azure |
This was referenced Dec 12, 2019
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Successful merges:
Box<T>representation and its use in FFI #62514 (ClarifyBox<T>representation and its use in FFI)unused_parenstriggers on macro by example code #66983 (Fixunused_parenstriggers on macro by example code)-Z print-type-sizes's handling of zero-sized fields. #67215 (Fix-Z print-type-sizes's handling of zero-sized fields.)register_dtor#67230 (Remove irelevant comment onregister_dtor)Failed merges:
r? @ghost