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typeck/pat.rs: extract calc_default_binding_mode.

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This commit is contained in:
Mazdak Farrokhzad 2019-08-23 16:06:33 +02:00
parent 3ec5d07b1d
commit 23dc37d21d
1 changed files with 34 additions and 23 deletions
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57
src/librustc_typeck/check/pat.rs
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@ -60,29 +60,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
PatKind::Path(qpath) => Some(self.resolve_ty_and_res_ufcs(qpath, pat.hir_id, pat.span)),
_ => None,
};
let is_non_ref_pat = self.is_non_ref_pat(pat, path_resolution.map(|(res, ..)| res));
let (expected, def_bm) = if is_non_ref_pat {
debug!("pattern is non reference pattern");
self.peel_off_references(pat, expected, def_bm)
} else {
// When you encounter a `&pat` pattern, reset to "by
// value". This is so that `x` and `y` here are by value,
// as they appear to be:
//
// ```
// match &(&22, &44) {
// (&x, &y) => ...
// }
// ```
//
// See issue #46688.
let def_bm = match pat.node {
PatKind::Ref(..) => ty::BindByValue(hir::MutImmutable),
_ => def_bm,
};
(expected, def_bm)
};
let is_nrp = self.is_non_ref_pat(pat, path_resolution.map(|(res, ..)| res));
let (expected, def_bm) = self.calc_default_binding_mode(pat, expected, def_bm, is_nrp);
let ty = match pat.node {
PatKind::Wild => {
@ -495,6 +474,38 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// subtyping.
}
/// Compute the new expected type and default binding mode from the old ones
/// as well as the pattern form we are currently checking.
fn calc_default_binding_mode(
&self,
pat: &'tcx hir::Pat,
expected: Ty<'tcx>,
def_bm: ty::BindingMode,
is_non_ref_pat: bool,
) -> (Ty<'tcx>, ty::BindingMode) {
if is_non_ref_pat {
debug!("pattern is non reference pattern");
self.peel_off_references(pat, expected, def_bm)
} else {
// When you encounter a `&pat` pattern, reset to "by
// value". This is so that `x` and `y` here are by value,
// as they appear to be:
//
// ```
// match &(&22, &44) {
// (&x, &y) => ...
// }
// ```
//
// See issue #46688.
let def_bm = match pat.node {
PatKind::Ref(..) => ty::BindByValue(hir::MutImmutable),
_ => def_bm,
};
(expected, def_bm)
}
}
/// Is the pattern a "non reference pattern"?
/// When the pattern is a path pattern, `opt_path_res` must be `Some(res)`.
fn is_non_ref_pat(&self, pat: &'tcx hir::Pat, opt_path_res: Option<Res>) -> bool {