diff --git a/src/librustc_trans/trans/_match.rs b/src/librustc_trans/trans/_match.rs index ada46ab7db719..f5155852aa00c 100644 --- a/src/librustc_trans/trans/_match.rs +++ b/src/librustc_trans/trans/_match.rs @@ -1226,30 +1226,50 @@ pub fn trans_match<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, /// Checks whether the binding in `discr` is assigned to anywhere in the expression `body` fn is_discr_reassigned(bcx: Block, discr: &ast::Expr, body: &ast::Expr) -> bool { - match discr.node { + let (vid, field) = match discr.node { ast::ExprPath(..) => match bcx.def(discr.id) { - def::DefLocal(vid) | def::DefUpvar(vid, _, _) => { - let mut rc = ReassignmentChecker { - node: vid, - reassigned: false - }; - { - let mut visitor = euv::ExprUseVisitor::new(&mut rc, bcx); - visitor.walk_expr(body); - } - rc.reassigned - } - _ => false + def::DefLocal(vid) | def::DefUpvar(vid, _, _) => (vid, None), + _ => return false + }, + ast::ExprField(ref base, field) => { + let vid = match bcx.tcx().def_map.borrow().get(&base.id) { + Some(&def::DefLocal(vid)) | Some(&def::DefUpvar(vid, _, _)) => vid, + _ => return false + }; + (vid, Some(mc::NamedField(field.node.name))) + }, + ast::ExprTupField(ref base, field) => { + let vid = match bcx.tcx().def_map.borrow().get(&base.id) { + Some(&def::DefLocal(vid)) | Some(&def::DefUpvar(vid, _, _)) => vid, + _ => return false + }; + (vid, Some(mc::PositionalField(field.node))) }, - _ => false + _ => return false + }; + + let mut rc = ReassignmentChecker { + node: vid, + field: field, + reassigned: false + }; + { + let mut visitor = euv::ExprUseVisitor::new(&mut rc, bcx); + visitor.walk_expr(body); } + rc.reassigned } struct ReassignmentChecker { node: ast::NodeId, + field: Option, reassigned: bool } +// Determine if the expression we're matching on is reassigned to within +// the body of the match's arm. +// We only care for the `mutate` callback since this check only matters +// for cases where the matched value is moved. impl<'tcx> euv::Delegate<'tcx> for ReassignmentChecker { fn consume(&mut self, _: ast::NodeId, _: Span, _: mc::cmt, _: euv::ConsumeMode) {} fn matched_pat(&mut self, _: &ast::Pat, _: mc::cmt, _: euv::MatchMode) {} @@ -1262,6 +1282,15 @@ impl<'tcx> euv::Delegate<'tcx> for ReassignmentChecker { match cmt.cat { mc::cat_upvar(mc::Upvar { id: ty::UpvarId { var_id: vid, .. }, .. }) | mc::cat_local(vid) => self.reassigned = self.node == vid, + mc::cat_interior(ref base_cmt, mc::InteriorField(field)) => { + match base_cmt.cat { + mc::cat_upvar(mc::Upvar { id: ty::UpvarId { var_id: vid, .. }, .. }) | + mc::cat_local(vid) => { + self.reassigned = self.node == vid && Some(field) == self.field + }, + _ => {} + } + }, _ => {} } } diff --git a/src/test/run-pass/issue-19367.rs b/src/test/run-pass/issue-19367.rs new file mode 100644 index 0000000000000..6083b340825d4 --- /dev/null +++ b/src/test/run-pass/issue-19367.rs @@ -0,0 +1,42 @@ +// Copyright 2014 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(tuple_indexing)] +struct S { + o: Option +} + +// Make sure we don't reuse the same alloca when matching +// on field of struct or tuple which we reassign in the match body. + +fn main() { + let mut a = (0i, Some("right".into_string())); + let b = match a.1 { + Some(v) => { + a.1 = Some("wrong".into_string()); + v + } + None => String::new() + }; + println!("{}", b); + assert_eq!(b, "right"); + + + let mut s = S{ o: Some("right".into_string()) }; + let b = match s.o { + Some(v) => { + s.o = Some("wrong".into_string()); + v + } + None => String::new(), + }; + println!("{}", b); + assert_eq!(b, "right"); +}