error: cannot determine a type for this bounded type parameter: unconstrained type #12721 Closed carllerche opened this Issue Mar 6, 2014 · 5 comments Closed Compilation bug? error: cannot determine a type
type parameter `W` is not constrained by the impl trait, self type, or predicates --> /tmp/icemaker_global_tempdir.MNIZNQo6CYeL/rustc_testrunner_tmpdir_reporting.Qq5ognT5KM0J/mvce.rs:5:10 | 5 | impl<'a, W: ?Sized> Q for [u8; N] {} | ^ unconstrained type parameter error:...
但是出现了错误,"Param unconstrained type parameter",Param未受到限制, 即没有出现在 System 中,也没有作为SystemParamFunction的关联类型,这只是作为SystemParamFunction的泛型参数,并没有被限制 为System添加泛型参数是不行的,因为它已经在App被作为了dyn trait Box<dyn System>,它需要动态派发 此时陷入了困境 想了...
AllTuples 将会是如下数据。我们再为 (SystemParam, ...) 这种内部成员全部实现了 SystemParam 的元组实现 SystemParam，实现代码如下：现在问题转到了为 SystemParamFunction 实现 System。我们尝试去实现它，但出现了错误："Param unconstrained type parameter"。Param 未受到限制，即没有出现在 System 中...
This RFC makes it an error to have a type or lifetime parameter that is not (transitively) used somewhere in the type. Nothing else is changed. 代码相当老旧(例如,CovariantType和ContravariantLifetime 已被PhantomData 替换),但概念仍然适用。 - Chayim Friedman...
这儿对泛型的约束很神奇,竟然是这样写Quantity<{ UL.unit_mul(UR) }>: ,如果去掉这个where,则会报错unconstrained generic constant。虽然现在还不懂是什么意思... error: unconstrained generic constant --> src\lib.rs:156:5 | 156 | type Output = Quantity<{ UL.unit_mul(UR) }>; | ^^^ | help:...
error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predica --> src/liballoc/slice.rs:608:6 | 608 | impl<T: Clone, V: Borrow<[T]>> Concat for [V] { | ^ unconstrained type parameter这是因为可能存在具有多个 Borrow<[_]> impls 的 V 类型...
error[E0207]: the type parameter `T` is not constrained by the impl trait, self type, or predica --> library/alloc/src/slice.rs:608:6 | 608 | impl<T: Clone, V: Borrow<[T]>> Concat for [V] { | ^ unconstrained type parameter 这是因为可能存在具有多个 Borrow<[_]> 表示的 V ...
error[E0207]: the type parameter `a` is not constrained by the impl trait, self type, or predicates --> ./test.rs:13:9 | 13 | impl<T, a> Overlap<for<'a> fn(&'a (), Assoc<'a, T, T>)> for T {} | ^ unconstrained type parameter ...
the arguments of the opaque type are not universal (i.e. free regions in the function) it's impossible to know how 'unconstrained and 'temp are related in the general case, especially if the opaque has more than 1 region parameter