auto merge of rust-lang#18124 : pnkfelix/rust/fsk-add-check-of-borrow-local-static, r=thestinger

Check for borrow of local variable introduced within static block. (Rather than ICE on it.) Fix rust-lang#18118.

Author: bors

src/librustc/middle/check_static.rs

@@ -57,13 +57,15 @@ struct GlobalChecker {
  static_consumptions: NodeSet,
  const_borrows: NodeSet,
  static_interior_borrows: NodeSet,
+ static_local_borrows: NodeSet,
 }
 
 pub fn check_crate(tcx: &ty::ctxt) {
  let mut checker = GlobalChecker {
  static_consumptions: NodeSet::new(),
  const_borrows: NodeSet::new(),
  static_interior_borrows: NodeSet::new(),
+ static_local_borrows: NodeSet::new(),
  };
  {
  let visitor = euv::ExprUseVisitor::new(&mut checker, tcx);
@@ -200,6 +202,14 @@ impl<'a, 'tcx, 'v> Visitor<'v> for CheckStaticVisitor<'a, 'tcx> {
  }
  }
 
+ // local variables in a block expression in a static context (i.e. being
+ // assigned to a static variable) cannot be borrowed.
+ if self.checker.static_local_borrows.remove(&e.id) {
+ self.tcx.sess.span_err(e.span, "cannot borrow a local variable inside \
+ a static block, define a separate static \
+ instead");
+ }
+
  match e.node {
  ast::ExprAddrOf(ast::MutMutable, _) => {
  if self.mode != InStaticMut {
@@ -298,8 +308,12 @@ impl euv::Delegate for GlobalChecker {
 
  mc::cat_downcast(..) |
  mc::cat_discr(..) |
- mc::cat_upvar(..) |
- mc::cat_local(..) => unreachable!(),
+ mc::cat_upvar(..) => unreachable!(),
+
+ mc::cat_local(..) => {
+ self.static_local_borrows.insert(borrow_id);
+ break
+ }
  }
  }
  }