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auto merge of #15083 : edwardw/rust/destructure-trait-ref, r=pcwalton

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Closes #15031.
This commit is contained in:
bors 2014-06-23 07:26:37 +00:00
commit 1efc02a9ec
3 changed files with 68 additions and 11 deletions
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36
src/librustc/middle/typeck/check/_match.rs
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@ -726,22 +726,38 @@ pub fn check_pat(pcx: &pat_ctxt, pat: &ast::Pat, expected: ty::t) {
}
// Helper function to check gc, box and & patterns
pub fn check_pointer_pat(pcx: &pat_ctxt,
pointer_kind: PointerKind,
inner: &ast::Pat,
pat_id: ast::NodeId,
span: Span,
expected: ty::t) {
fn check_pointer_pat(pcx: &pat_ctxt,
pointer_kind: PointerKind,
inner: &ast::Pat,
pat_id: ast::NodeId,
span: Span,
expected: ty::t) {
let fcx = pcx.fcx;
let tcx = fcx.ccx.tcx;
let check_inner: |ty::t| = |e_inner| {
check_pat(pcx, inner, e_inner);
fcx.write_ty(pat_id, expected);
match ty::get(e_inner).sty {
ty::ty_trait(_) if pat_is_binding(&tcx.def_map, inner) => {
// This is "x = SomeTrait" being reduced from
// "let &x = &SomeTrait" or "let box x = Box<SomeTrait>", an error.
check_pat(pcx, inner, ty::mk_err());
tcx.sess.span_err(
span,
format!("type `{}` cannot be dereferenced",
fcx.infcx().ty_to_str(expected)).as_slice());
fcx.write_error(pat_id);
}
_ => {
check_pat(pcx, inner, e_inner);
fcx.write_ty(pat_id, expected);
}
}
};
match *structure_of(fcx, span, expected) {
ty::ty_uniq(e_inner) if pointer_kind == Send && !ty::type_is_trait(e_inner) => {
ty::ty_uniq(e_inner) if pointer_kind == Send => {
check_inner(e_inner);
}
ty::ty_rptr(_, e_inner) if pointer_kind == Borrowed && !ty::type_is_trait(e_inner.ty) => {
ty::ty_rptr(_, e_inner) if pointer_kind == Borrowed => {
check_inner(e_inner.ty);
}
_ => {