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Diffstat (limited to 'compiler/rustc_error_codes/src/error_codes/E0750.md')
-rw-r--r-- | compiler/rustc_error_codes/src/error_codes/E0750.md | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/compiler/rustc_error_codes/src/error_codes/E0750.md b/compiler/rustc_error_codes/src/error_codes/E0750.md new file mode 100644 index 000000000..905e852f8 --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0750.md @@ -0,0 +1,18 @@ +A negative impl was made default impl. + +Erroneous code example: + +```compile_fail,E0750 +# #![feature(negative_impls)] +# #![feature(specialization)] +trait MyTrait { + type Foo; +} + +default impl !MyTrait for u32 {} // error! +# fn main() {} +``` + +Negative impls cannot be default impls. A default impl supplies default values +for the items within to be used by other impls, whereas a negative impl declares +that there are no other impls. Combining it does not make sense. |