diff --git a/src/librustc_const_eval/pattern.rs b/src/librustc_const_eval/pattern.rs index 4bd797afd06..a6c886533c8 100644 --- a/src/librustc_const_eval/pattern.rs +++ b/src/librustc_const_eval/pattern.rs @@ -117,6 +117,7 @@ impl<'a, 'gcx, 'tcx> Pattern<'tcx> { if !pcx.errors.is_empty() { span_bug!(pat.span, "encountered errors lowering pattern: {:?}", pcx.errors) } + debug!("Pattern::from_hir({:?}) = {:?}", pat, result); result } } @@ -346,6 +347,40 @@ impl<'a, 'gcx, 'tcx> PatternContext<'a, 'gcx, 'tcx> { pat.as_ref().map(|p| self.lower_pattern(p)) } + fn flatten_nested_slice_patterns( + &mut self, + prefix: Vec>, + slice: Option>, + suffix: Vec>) + -> (Vec>, Option>, Vec>) + { + let orig_slice = match slice { + Some(orig_slice) => orig_slice, + None => return (prefix, slice, suffix) + }; + let orig_prefix = prefix; + let orig_suffix = suffix; + + // dance because of intentional borrow-checker stupidity. + let kind = *orig_slice.kind; + match kind { + PatternKind::Slice { prefix, slice, mut suffix } | + PatternKind::Array { prefix, slice, mut suffix } => { + let mut orig_prefix = orig_prefix; + + orig_prefix.extend(prefix); + suffix.extend(orig_suffix); + + (orig_prefix, slice, suffix) + } + _ => { + (orig_prefix, Some(Pattern { + kind: box kind, ..orig_slice + }), orig_suffix) + } + } + } + fn slice_or_array_pattern( &mut self, span: Span, @@ -355,24 +390,22 @@ impl<'a, 'gcx, 'tcx> PatternContext<'a, 'gcx, 'tcx> { suffix: &[P]) -> PatternKind<'tcx> { + let prefix = self.lower_patterns(prefix); + let slice = self.lower_opt_pattern(slice); + let suffix = self.lower_patterns(suffix); + let (prefix, slice, suffix) = + self.flatten_nested_slice_patterns(prefix, slice, suffix); + match ty.sty { ty::TySlice(..) => { // matching a slice or fixed-length array - PatternKind::Slice { - prefix: self.lower_patterns(prefix), - slice: self.lower_opt_pattern(slice), - suffix: self.lower_patterns(suffix), - } + PatternKind::Slice { prefix: prefix, slice: slice, suffix: suffix } } ty::TyArray(_, len) => { // fixed-length array assert!(len >= prefix.len() + suffix.len()); - PatternKind::Array { - prefix: self.lower_patterns(prefix), - slice: self.lower_opt_pattern(slice), - suffix: self.lower_patterns(suffix), - } + PatternKind::Array { prefix: prefix, slice: slice, suffix: suffix } } _ => { diff --git a/src/test/compile-fail/issue-26158.rs b/src/test/compile-fail/issue-26158.rs new file mode 100644 index 00000000000..54f5313aed1 --- /dev/null +++ b/src/test/compile-fail/issue-26158.rs @@ -0,0 +1,16 @@ +// Copyright 2016 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(slice_patterns)] + +fn main() { + let x: &[u32] = &[]; + let &[[ref _a, ref _b..]..] = x; //~ ERROR refutable pattern +} diff --git a/src/test/run-pass/vec-matching.rs b/src/test/run-pass/vec-matching.rs index 97006f54cd9..bd0731a555c 100644 --- a/src/test/run-pass/vec-matching.rs +++ b/src/test/run-pass/vec-matching.rs @@ -144,6 +144,20 @@ fn e() { assert_eq!(c, 1); } +fn f() { + let x = &[1, 2, 3, 4, 5]; + let [a, [b, [c, ..].., d].., e] = *x; + assert_eq!((a, b, c, d, e), (1, 2, 3, 4, 5)); + + let x: &[isize] = x; + let (a, b, c, d, e) = match *x { + [a, [b, [c, ..].., d].., e] => (a, b, c, d, e), + _ => unimplemented!() + }; + + assert_eq!((a, b, c, d, e), (1, 2, 3, 4, 5)); +} + pub fn main() { a(); b(); @@ -151,4 +165,5 @@ pub fn main() { c(); d(); e(); + f(); }