prevent more deallocations of statics

Author: oli-obk

src/eval_context.rs

@@ -329,6 +329,9 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                         }
                     },
                 }
+                // see comment on `initialized` field
+                assert!(!global_value.initialized);
+                global_value.initialized = true;
                 assert!(global_value.mutable);
                 global_value.mutable = mutable;
             } else {
@@ -868,7 +871,10 @@ impl<'a, 'tcx> EvalContext<'a, 'tcx> {
                     _ => {
                         let ptr = self.alloc_ptr_with_substs(global_val.ty, cid.substs)?;
                         self.write_value_to_ptr(global_val.value, ptr, global_val.ty)?;
-                        self.memory.mark_static(ptr.alloc_id, global_val.mutable)?;
+                        // see comment on `initialized` field
+                        if global_val.initialized {
+                            self.memory.mark_static(ptr.alloc_id, global_val.mutable)?;
+                        }
                         let lval = self.globals.get_mut(&cid).expect("already checked");
                         *lval = Global {
                             value: Value::ByRef(ptr),

src/lvalue.rs

@@ -57,6 +57,11 @@ pub struct GlobalId<'tcx> {
 #[derive(Copy, Clone, Debug)]
 pub struct Global<'tcx> {
     pub(super) value: Value,
+    /// Only used in `force_allocation` to ensure we don't mark the memory
+    /// before the static is initialized. It is possible to convert a
+    /// global which initially is `Value::ByVal(PrimVal::Undef)` and gets
+    /// lifted to an allocation before the static is fully initialized
+    pub(super) initialized: bool,
     pub(super) mutable: bool,
     pub(super) ty: Ty<'tcx>,
 }
@@ -102,6 +107,7 @@ impl<'tcx> Global<'tcx> {
             value: Value::ByVal(PrimVal::Undef),
             mutable: true,
             ty,
+            initialized: false,
         }
     }
 }

tests/run-pass/issue-5917.rs

@@ -0,0 +1,17 @@
+// Copyright 2013 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 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+
+struct T (&'static [isize]);
+static t : T = T (&[5, 4, 3]);
+pub fn main () {
+    let T(ref v) = t;
+    assert_eq!(v[0], 5);
+}