From 35dd62e915905b6a93e2069a6d155cdf00cd254a Mon Sep 17 00:00:00 2001 From: Lukas Wirth Date: Tue, 24 Nov 2020 13:41:21 +0100 Subject: Properly infer tuple patterns when encountering ellipsis --- crates/hir_ty/src/infer/pat.rs | 25 +++++++++++++++++-------- 1 file changed, 17 insertions(+), 8 deletions(-) (limited to 'crates/hir_ty/src/infer') diff --git a/crates/hir_ty/src/infer/pat.rs b/crates/hir_ty/src/infer/pat.rs index cde2ab82b..b3fd74eab 100644 --- a/crates/hir_ty/src/infer/pat.rs +++ b/crates/hir_ty/src/infer/pat.rs @@ -111,20 +111,29 @@ impl<'a> InferenceContext<'a> { let expected = expected; let ty = match &body[pat] { - Pat::Tuple { ref args, .. } => { + Pat::Tuple { ref args, ellipsis } => { let expectations = match expected.as_tuple() { Some(parameters) => &*parameters.0, _ => &[], }; - let expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown)); - let inner_tys = args - .iter() - .zip(expectations_iter) - .map(|(&pat, ty)| self.infer_pat(pat, ty, default_bm)) - .collect(); + let (pre, post) = match ellipsis { + &Some(idx) => args.split_at(idx), + None => (&args[..], &[][..]), + }; + let uncovered_range = pre.len()..expectations.len().saturating_sub(post.len()); + let mut expectations_iter = expectations.iter().chain(repeat(&Ty::Unknown)); + let mut infer_pat = |(&pat, ty)| self.infer_pat(pat, ty, default_bm); + + let mut inner_tys = Vec::with_capacity(expectations.len()); + inner_tys.extend(pre.iter().zip(expectations_iter.by_ref()).map(&mut infer_pat)); + inner_tys.extend(expectations_iter.by_ref().take(uncovered_range.len()).cloned()); + inner_tys.extend(post.iter().zip(expectations_iter).map(infer_pat)); - Ty::apply(TypeCtor::Tuple { cardinality: args.len() as u16 }, Substs(inner_tys)) + Ty::apply( + TypeCtor::Tuple { cardinality: inner_tys.len() as u16 }, + Substs(inner_tys.into()), + ) } Pat::Or(ref pats) => { if let Some((first_pat, rest)) = pats.split_first() { -- cgit v1.2.3