user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Update documentation.

Browse source 
This commit updates the unstable book and diagnostics to reflect that
the `#[non_exhaustive]` attribute is now available for enum variants.
This commit is contained in:
David Wood 2019-03-23 02:35:22 +01:00
parent 3a88cd7778
commit 18938416e4
No known key found for this signature in database
GPG key ID: 01760B4F9F53F154
2 changed files with 13 additions and 11 deletions
Download patch file Download diff file Expand all files Collapse all files

11
src/doc/unstable-book/src/language-features/non-exhaustive.md
View file

@ -7,10 +7,12 @@ The tracking issue for this feature is: [#44109]
------------------------
The `non_exhaustive` gate allows you to use the `#[non_exhaustive]` attribute
on structs and enums. When applied within a crate, users of the crate will need
to use the `_` pattern when matching enums and use the `..` pattern when
matching structs. Structs marked as `non_exhaustive` will not be able to be
created normally outside of the defining crate. This is demonstrated below:
on structs, enums and enum variants. When applied within a crate, users of the
crate will need to use the `_` pattern when matching enums and use the `..`
pattern when matching structs. Enum variants cannot be matched against.
Structs and enum variants marked as `non_exhaustive` will not be able to
be created normally outside of the defining crate. This is demonstrated
below:
```rust,ignore (pseudo-Rust)
use std::error::Error as StdError;
@ -72,4 +74,3 @@ let config = Config { window_width: 640, window_height: 480 };
// when marked non_exhaustive.
let &Config { window_width, window_height, .. } = config;
```

13
src/librustc_typeck/diagnostics.rs
View file

@ -4341,11 +4341,12 @@ foo.method(); // Ok!
"##,
E0638: r##"
This error indicates that the struct or enum must be matched non-exhaustively
as it has been marked as `non_exhaustive`.
This error indicates that the struct, enum or enum variant must be matched
non-exhaustively as it has been marked as `non_exhaustive`.
When applied within a crate, downstream users of the crate will need to use the
`_` pattern when matching enums and use the `..` pattern when matching structs.
Downstream crates cannot match against non-exhaustive enum variants.
For example, in the below example, since the enum is marked as
`non_exhaustive`, it is required that downstream crates match non-exhaustively
@ -4390,10 +4391,10 @@ Similarly, for structs, match with `..` to avoid this error.
"##,
E0639: r##"
This error indicates that the struct or enum cannot be instantiated from
outside of the defining crate as it has been marked as `non_exhaustive` and as
such more fields/variants may be added in future that could cause adverse side
effects for this code.
This error indicates that the struct, enum or enum variant cannot be
instantiated from outside of the defining crate as it has been marked
as `non_exhaustive` and as such more fields/variants may be added in
future that could cause adverse side effects for this code.
It is recommended that you look for a `new` function or equivalent in the
crate's documentation.