diff options
| -rw-r--r-- | src/librustc_typeck/check/callee.rs | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/src/librustc_typeck/check/callee.rs b/src/librustc_typeck/check/callee.rs index f10985a4d0e..c59c143f74b 100644 --- a/src/librustc_typeck/check/callee.rs +++ b/src/librustc_typeck/check/callee.rs @@ -144,6 +144,13 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> { _ => {} } + // Now, we look for the implementation of a Fn trait on the object's type. + // We first do it with the explicit instruction to look for an impl of + // `Fn<Tuple>`, with the tuple `Tuple` having an arity corresponding + // to the number of call parameters. + // If that fails (or_else branch), we try again without specifying the + // shape of the tuple (hence the None). This allows to detect an Fn trait + // is implemented, and use this information for diagnostic. self.try_overloaded_call_traits(call_expr, adjusted_ty, Some(arg_exprs)) .or_else(|| self.try_overloaded_call_traits(call_expr, adjusted_ty, None)) .map(|(autoref, method)| { |