diff options
| -rw-r--r-- | src/librustc_typeck/check/pat.rs | 159 |
1 files changed, 86 insertions, 73 deletions
diff --git a/src/librustc_typeck/check/pat.rs b/src/librustc_typeck/check/pat.rs index 55a9360b83f..7b78474e799 100644 --- a/src/librustc_typeck/check/pat.rs +++ b/src/librustc_typeck/check/pat.rs @@ -52,8 +52,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { def_bm: ty::BindingMode, discrim_span: Option<Span>, ) { - let tcx = self.tcx; - debug!("check_pat_walk(pat={:?},expected={:?},def_bm={:?})", pat, expected, def_bm); let path_resolution = match &pat.node { @@ -114,77 +112,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { self.check_pat_ref(pat, inner, mutbl, expected, def_bm, discrim_span) } PatKind::Slice(ref before, ref slice, ref after) => { - let expected_ty = self.structurally_resolved_type(pat.span, expected); - let (inner_ty, slice_ty) = match expected_ty.sty { - ty::Array(inner_ty, size) => { - if let Some(size) = size.try_eval_usize(tcx, self.param_env) { - let min_len = before.len() as u64 + after.len() as u64; - if slice.is_none() { - if min_len != size { - struct_span_err!( - tcx.sess, pat.span, E0527, - "pattern requires {} elements but array has {}", - min_len, size) - .span_label(pat.span, format!("expected {} elements", size)) - .emit(); - } - (inner_ty, tcx.types.err) - } else if let Some(rest) = size.checked_sub(min_len) { - (inner_ty, tcx.mk_array(inner_ty, rest)) - } else { - struct_span_err!(tcx.sess, pat.span, E0528, - "pattern requires at least {} elements but array has {}", - min_len, size) - .span_label(pat.span, - format!("pattern cannot match array of {} elements", size)) - .emit(); - (inner_ty, tcx.types.err) - } - } else { - struct_span_err!( - tcx.sess, - pat.span, - E0730, - "cannot pattern-match on an array without a fixed length", - ).emit(); - (inner_ty, tcx.types.err) - } - } - ty::Slice(inner_ty) => (inner_ty, expected_ty), - _ => { - if !expected_ty.references_error() { - let mut err = struct_span_err!( - tcx.sess, pat.span, E0529, - "expected an array or slice, found `{}`", - expected_ty); - if let ty::Ref(_, ty, _) = expected_ty.sty { - match ty.sty { - ty::Array(..) | ty::Slice(..) => { - err.help("the semantics of slice patterns changed \ - recently; see issue #62254"); - } - _ => {} - } - } - - err.span_label( pat.span, - format!("pattern cannot match with input type `{}`", expected_ty) - ).emit(); - } - (tcx.types.err, tcx.types.err) - } - }; - - for elt in before { - self.check_pat_walk(&elt, inner_ty, def_bm, discrim_span); - } - if let Some(ref slice) = *slice { - self.check_pat_walk(&slice, slice_ty, def_bm, discrim_span); - } - for elt in after { - self.check_pat_walk(&elt, inner_ty, def_bm, discrim_span); - } - expected_ty + let slice = slice.as_deref(); + self.check_pat_slice(pat.span, before, slice, after, expected, def_bm, discrim_span) } }; @@ -1070,4 +999,88 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { tcx.types.err } } + + fn check_pat_slice( + &self, + span: Span, + before: &'tcx [P<hir::Pat>], + slice: Option<&'tcx hir::Pat>, + after: &'tcx [P<hir::Pat>], + expected: Ty<'tcx>, + def_bm: ty::BindingMode, + discrim_span: Option<Span>, + ) -> Ty<'tcx> { + let tcx = self.tcx; + let expected_ty = self.structurally_resolved_type(span, expected); + let (inner_ty, slice_ty) = match expected_ty.sty { + ty::Array(inner_ty, size) => { + if let Some(size) = size.try_eval_usize(tcx, self.param_env) { + let min_len = before.len() as u64 + after.len() as u64; + if slice.is_none() { + if min_len != size { + struct_span_err!( + tcx.sess, span, E0527, + "pattern requires {} elements but array has {}", + min_len, size + ) + .span_label(span, format!("expected {} elements", size)) + .emit(); + } + (inner_ty, tcx.types.err) + } else if let Some(rest) = size.checked_sub(min_len) { + (inner_ty, tcx.mk_array(inner_ty, rest)) + } else { + let msg = format!("pattern cannot match array of {} elements", size); + struct_span_err!( + tcx.sess, span, E0528, + "pattern requires at least {} elements but array has {}", + min_len, size + ) + .span_label(span, msg) + .emit(); + (inner_ty, tcx.types.err) + } + } else { + struct_span_err!( + tcx.sess, span, E0730, + "cannot pattern-match on an array without a fixed length", + ) + .emit(); + (inner_ty, tcx.types.err) + } + } + ty::Slice(inner_ty) => (inner_ty, expected_ty), + _ => { + if !expected_ty.references_error() { + let mut err = struct_span_err!( + tcx.sess, span, E0529, + "expected an array or slice, found `{}`", + expected_ty + ); + if let ty::Ref(_, ty, _) = expected_ty.sty { + if let ty::Array(..) | ty::Slice(..) = ty.sty { + err.help("the semantics of slice patterns changed \ + recently; see issue #62254"); + } + } + + let msg = format!("pattern cannot match with input type `{}`", expected_ty); + err.span_label(span, msg); + err.emit(); + } + (tcx.types.err, tcx.types.err) + } + }; + + for elt in before { + self.check_pat_walk(&elt, inner_ty, def_bm, discrim_span); + } + if let Some(slice) = slice { + self.check_pat_walk(&slice, slice_ty, def_bm, discrim_span); + } + for elt in after { + self.check_pat_walk(&elt, inner_ty, def_bm, discrim_span); + } + expected_ty + } } |