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Niko Matsakis 2017-09-22 10:37:46 -04:00 committed by Guillaume Gomez
parent c30435be5b
commit 21d4ba2ea6
1 changed files with 10 additions and 0 deletions
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10
src/librustc_typeck/check/demand.rs
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@ -262,14 +262,24 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
None
}
(_, &ty::TyRef(_, checked)) => {
// We have `&T`, check if what was expected was `T`. If so,
// we may want to suggest adding a `*`, or removing
// a `&`.
//
// (But, also check check the `expn_info()` to see if this is
// a macro; if so, it's hard to extract the text and make a good
// suggestion, so don't bother.)
if self.infcx.can_sub(self.param_env, checked.ty, &expected).is_ok() &&
expr.span.ctxt().outer().expn_info().is_none() {
match expr.node {
// Maybe remove `&`?
hir::ExprAddrOf(_, ref expr) => {
if let Ok(code) = self.tcx.sess.codemap().span_to_snippet(expr.span) {
return Some(format!("try with `{}`", code));
}
}
// Maybe add `*`? Only if `T: Copy`.
_ => {
if !self.infcx.type_moves_by_default(self.param_env,
checked.ty,