Zero locals that are inited via alt expressions. Closes #945

src/comp/middle/trans.rs

@@ -4664,6 +4664,7 @@ fn init_local(bcx: @block_ctxt, local: @ast::local) -> @block_ctxt {
                  ccx: ccx};
         fn visit_expr(ex: @ast::expr, e: env, v: vt<env>) {
             let might_not_init = alt ex.node {
+              ast::expr_alt(_, _) { true }
               ast::expr_ret(_) { true }
               ast::expr_break. { true }
               ast::expr_cont. { true }

src/test/run-fail/unwind-alt.rs

@@ -0,0 +1,12 @@
+// Issue #945
+// error-pattern:non-exhaustive match failure
+fn test_box() {
+    @0;
+}
+fn test_str() {
+    let res = alt false { true { "happy" } };
+}
+fn main() {
+    test_box();
+    test_str();
+}