Add note when FnPtr
vs. FnDef
impl trait
#106665
Merged
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I encountered an instance where an
FnPtr
implemented a trait, but I was passing anFnDef
. I was confused for an hour and to examine the source code of the trait's crate's tests in order to understand how to cast it properly (it didn't help that it was behind a reference). To the end user, it might not be immediately obvious that they are different and how to convert from anFnDef
to anFnPtr
, but it is necessary to cast to the generic function in order to compile. It is thus useful to suggestas
in the help note, (even if theFn
output implements the trait).