nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2025-04-17 06:26:55 +00:00
Code Issues Packages Projects Releases Wiki Activity

Adjust documentation

Browse Source
This commit is contained in:
Yuki Okushi 2021-06-14 07:05:14 +09:00
parent ea188e9d21
commit 4e755a96a7
No known key found for this signature in database
GPG Key ID: DABA5B072961C18A
1 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
compiler/rustc_error_codes/src/error_codes/E0690.md
View File

@ -1,19 +1,19 @@
A struct with the representation hint `repr(transparent)` had zero or more than
one fields that were not guaranteed to be zero-sized.
A struct with the representation hint `repr(transparent)` had two or more fields
that were not guaranteed to be zero-sized.
Erroneous code example:
```compile_fail,E0690
#[repr(transparent)]
struct LengthWithUnit<U> { // error: transparent struct needs exactly one
struct LengthWithUnit<U> { // error: transparent struct needs at most one
value: f32, // non-zero-sized field, but has 2
unit: U,
}
```
Because transparent structs are represented exactly like one of their fields at
run time, said field must be uniquely determined. If there is no field, or if
there are multiple fields, it is not clear how the struct should be represented.
run time, said field must be uniquely determined. If there are multiple fields,
it is not clear how the struct should be represented.
Note that fields of zero-sized types (e.g., `PhantomData`) can also exist
alongside the field that contains the actual data, they do not count for this
error. When generic types are involved (as in the above example), an error is