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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /compiler/rustc_error_codes/src/error_codes/E0784.md | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'compiler/rustc_error_codes/src/error_codes/E0784.md')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0784.md | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0784.md b/compiler/rustc_error_codes/src/error_codes/E0784.md new file mode 100644 index 000000000..b20b7039b --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0784.md @@ -0,0 +1,32 @@ +A union expression does not have exactly one field. + +Erroneous code example: + +```compile_fail,E0784 +union Bird { + pigeon: u8, + turtledove: u16, +} + +let bird = Bird {}; // error +let bird = Bird { pigeon: 0, turtledove: 1 }; // error +``` + +The key property of unions is that all fields of a union share common storage. +As a result, writes to one field of a union can overwrite its other fields, and +size of a union is determined by the size of its largest field. + +You can find more information about the union types in the [Rust reference]. + +Working example: + +``` +union Bird { + pigeon: u8, + turtledove: u16, +} + +let bird = Bird { pigeon: 0 }; // OK +``` + +[Rust reference]: https://doc.rust-lang.org/reference/items/unions.html |