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All fixed-size array impls show up as <unevaluated[]> #49208
Description
After #46882, when a trait bound fails and the trait was implemented by fixed-size arrays, the compiler will display an error like:
= help: the following implementations were found:
<[T; <unevaluated[]>] as Trait>
<[T; <unevaluated[]>] as Trait>
<[T; <unevaluated[]>] as Trait>
<[T; <unevaluated[]>] as Trait>
and 31 others
Which is pretty unhelpful. A solution would be to evaluate these and/or to show evaluated bounds preferably.
Activity
oli-obk commentedon Mar 20, 2018
I can't reproduce triggering an error with these messages, do you have an example? I need it for a regression test, the fix was indeed as simple
eira-fransham commentedon Mar 21, 2018
It only appears if you explicitly disambiguate the trait, like
<[T; N] as Foo>::foo(). Playground link here.estebank commentedon Mar 21, 2018
@oli-obk are you displaying these as
<[(); _] as Foo>? I feel that'd be a reasonable output for this.oli-obk commentedon Mar 22, 2018
@estebank that would be a better fallback than
<unevaluated[]>, but I'm currently trying to get at the actual value (though that triggers cycle errors atm when building libcore's array impls ^^)eira-fransham commentedon Mar 22, 2018
@estebank That's better in some ways, but kinda implies that
for<const T> [(); T]: FooRollup merge of rust-lang#49262 - oli-obk:fixed_size_array_len, r=est…
Rollup merge of rust-lang#49262 - oli-obk:fixed_size_array_len, r=est…