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Diffstat (limited to 'compiler/rustc_error_codes/src/error_codes/E0321.md')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0321.md | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0321.md b/compiler/rustc_error_codes/src/error_codes/E0321.md new file mode 100644 index 000000000..bcfc12897 --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0321.md @@ -0,0 +1,21 @@ +A cross-crate opt-out trait was implemented on something which wasn't a struct +or enum type. + +Erroneous code example: + +```compile_fail,E0321 +#![feature(auto_traits)] + +struct Foo; + +impl !Sync for Foo {} + +unsafe impl Send for &'static Foo {} +// error: cross-crate traits with a default impl, like `core::marker::Send`, +// can only be implemented for a struct/enum type, not +// `&'static Foo` +``` + +Only structs and enums are permitted to impl Send, Sync, and other opt-out +trait, and the struct or enum must be local to the current crate. So, for +example, `unsafe impl Send for Rc<Foo>` is not allowed. |