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new rules for merging expected and supplied types in closure signatures #45072

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Merged
merged 4 commits into from
Nov 5, 2017
Merged

new rules for merging expected and supplied types in closure signatures #45072

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11118dc
add some better debugs
nikomatsakis Sep 28, 2017
ea4db35
move `ty_of_closure` into `check/closure.rs`, its only caller
nikomatsakis Sep 28, 2017
053383d
new rules for merging expected/supplied types in closure signatures
nikomatsakis Oct 6, 2017
e8a96c9
fallback to provided signature in the event of a type error
nikomatsakis Nov 2, 2017
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5 changes: 4 additions & 1 deletion src/librustc/infer/higher_ranked/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,10 @@ impl<'a, 'gcx, 'tcx> CombineFields<'a, 'gcx, 'tcx> {
.filter(|&&r| !skol_resolution_map.contains_key(r))
.cloned()
.next()
.expect("no representative region");
.unwrap_or_else(|| {
bug!("no representative region for `{:?}` in `{:?}`",
skol, regions)
});

(skol, representative)
})
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54 changes: 0 additions & 54 deletions src/librustc_typeck/astconv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1206,60 +1206,6 @@ impl<'o, 'gcx: 'tcx, 'tcx> AstConv<'gcx, 'tcx>+'o {
bare_fn_ty
}

pub fn ty_of_closure(&self,
unsafety: hir::Unsafety,
decl: &hir::FnDecl,
abi: abi::Abi,
expected_sig: Option<ty::FnSig<'tcx>>)
-> ty::PolyFnSig<'tcx>
{
debug!("ty_of_closure(expected_sig={:?})",
expected_sig);

let input_tys = decl.inputs.iter().enumerate().map(|(i, a)| {
let expected_arg_ty = expected_sig.as_ref().and_then(|e| {
// no guarantee that the correct number of expected args
// were supplied
if i < e.inputs().len() {
Some(e.inputs()[i])
} else {
None
}
});
self.ty_of_arg(a, expected_arg_ty)
});

let expected_ret_ty = expected_sig.as_ref().map(|e| e.output());

let output_ty = match decl.output {
hir::Return(ref output) => {
if let (&hir::TyInfer, Some(expected_ret_ty)) = (&output.node, expected_ret_ty) {
self.record_ty(output.hir_id, expected_ret_ty, output.span);
expected_ret_ty
} else {
self.ast_ty_to_ty(&output)
}
}
hir::DefaultReturn(span) => {
if let Some(expected_ret_ty) = expected_ret_ty {
expected_ret_ty
} else {
self.ty_infer(span)
}
}
};

debug!("ty_of_closure: output_ty={:?}", output_ty);

ty::Binder(self.tcx().mk_fn_sig(
input_tys,
output_ty,
decl.variadic,
unsafety,
abi
))
}

/// Given the bounds on an object, determines what single region bound (if any) we can
/// use to summarize this type. The basic idea is that we will use the bound the user
/// provided, if they provided one, and otherwise search the supertypes of trait bounds
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