Added miri error for evaluating foreign statics.

Updated tests accordingly.

Author: Alexander Regueiro

src/librustc/ich/impls_ty.rs

@@ -574,6 +574,7 @@ for ::mir::interpret::EvalErrorKind<'gcx, O> {
             InvalidNullPointerUsage |
             ReadPointerAsBytes |
             ReadBytesAsPointer |
+            ReadForeignStatic |
             InvalidPointerMath |
             ReadUndefBytes |
             DeadLocal |

src/librustc/mir/interpret/error.rs

@@ -83,6 +83,7 @@ pub enum EvalErrorKind<'tcx, O> {
     InvalidNullPointerUsage,
     ReadPointerAsBytes,
     ReadBytesAsPointer,
+    ReadForeignStatic,
     InvalidPointerMath,
     ReadUndefBytes,
     DeadLocal,
@@ -196,6 +197,8 @@ impl<'tcx, O> EvalErrorKind<'tcx, O> {
                 "a raw memory access tried to access part of a pointer value as raw bytes",
             ReadBytesAsPointer =>
                 "a memory access tried to interpret some bytes as a pointer",
+            ReadForeignStatic =>
+                "tried to read foreign (extern) static",
             InvalidPointerMath =>
                 "attempted to do invalid arithmetic on pointers that would leak base addresses, e.g. comparing pointers into different allocations",
             ReadUndefBytes =>

src/librustc/ty/structural_impls.rs

@@ -506,6 +506,7 @@ impl<'a, 'tcx, O: Lift<'tcx>> Lift<'tcx> for interpret::EvalErrorKind<'a, O> {
             InvalidNullPointerUsage => InvalidNullPointerUsage,
             ReadPointerAsBytes => ReadPointerAsBytes,
             ReadBytesAsPointer => ReadBytesAsPointer,
+            ReadForeignStatic => ReadForeignStatic,
             InvalidPointerMath => InvalidPointerMath,
             ReadUndefBytes => ReadUndefBytes,
             DeadLocal => DeadLocal,

src/librustc_mir/interpret/const_eval.rs

@@ -375,7 +375,7 @@ impl<'mir, 'tcx> super::Machine<'mir, 'tcx> for CompileTimeEvaluator {
             Ok(None)
         } else {
             Err(
-                ConstEvalError::NeedsRfc("Pointer arithmetic or comparison".to_string()).into(),
+                ConstEvalError::NeedsRfc("pointer arithmetic or comparison".to_string()).into(),
             )
         }
     }
@@ -405,7 +405,7 @@ impl<'mir, 'tcx> super::Machine<'mir, 'tcx> for CompileTimeEvaluator {
         _dest: Place,
     ) -> EvalResult<'tcx> {
         Err(
-            ConstEvalError::NeedsRfc("Heap allocations via `box` keyword".to_string()).into(),
+            ConstEvalError::NeedsRfc("heap allocations via `box` keyword".to_string()).into(),
         )
     }
 

src/librustc_mir/interpret/memory.rs

@@ -280,6 +280,9 @@ impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
 /// Allocation accessors
 impl<'a, 'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'a, 'mir, 'tcx, M> {
     fn const_eval_static(&self, def_id: DefId) -> EvalResult<'tcx, &'tcx Allocation> {
+        if self.tcx.is_foreign_item(def_id) {
+            return err!(ReadForeignStatic);
+        }
         let instance = Instance::mono(self.tcx.tcx, def_id);
         let gid = GlobalId {
             instance,

src/test/compile-fail/const-fn-not-safe-for-const.rs

@@ -29,7 +29,6 @@ static Y: u32 = 0;
 const fn get_Y() -> u32 {
     Y
         //~^ ERROR E0013
-        //~| ERROR cannot refer to statics by value
 }
 
 const fn get_Y_addr() -> &'static u32 {
@@ -49,5 +48,4 @@ const fn get() -> u32 {
     //~| ERROR let bindings in constant functions are unstable
 }
 
-fn main() {
-}
+fn main() {}

src/test/compile-fail/issue-14227.rs

@@ -13,6 +13,7 @@
 extern {
     pub static symbol: ();
 }
-static CRASH: () = symbol; //~ cannot refer to other statics by value
+static CRASH: () = symbol;
+//~^ ERROR constant evaluation error
 
 fn main() {}

src/test/compile-fail/issue-17718-references.rs

@@ -22,14 +22,13 @@ static T4: &'static usize = &S;
 
 const T5: usize = C;
 const T6: usize = S; //~ ERROR: constants cannot refer to statics
-//~^ cannot refer to statics
 static T7: usize = C;
-static T8: usize = S; //~ ERROR: cannot refer to other statics by value
+static T8: usize = S;
 
 const T9: Struct = Struct { a: C };
-const T10: Struct = Struct { a: S }; //~ ERROR: cannot refer to statics by value
+const T10: Struct = Struct { a: S };
 //~^ ERROR: constants cannot refer to statics
 static T11: Struct = Struct { a: C };
-static T12: Struct = Struct { a: S }; //~ ERROR: cannot refer to other statics by value
+static T12: Struct = Struct { a: S };
 
 fn main() {}

src/test/compile-fail/issue-28324.rs

@@ -15,6 +15,6 @@ extern {
 }
 
 pub static BAZ: u32 = *&error_message_count;
-//~^ ERROR cannot refer to other statics by value
+//~^ ERROR constant evaluation error
 
 fn main() {}

src/test/compile-fail/thread-local-in-ctfe.rs

@@ -15,22 +15,19 @@ static A: u32 = 1;
 
 static B: u32 = A;
 //~^ ERROR thread-local statics cannot be accessed at compile-time
-//~| ERROR cannot refer to other statics by value
 
 static C: &u32 = &A;
 //~^ ERROR thread-local statics cannot be accessed at compile-time
 
 const D: u32 = A;
 //~^ ERROR thread-local statics cannot be accessed at compile-time
-//~| ERROR cannot refer to statics by value
 
 const E: &u32 = &A;
 //~^ ERROR thread-local statics cannot be accessed at compile-time
 
 const fn f() -> u32 {
     A
     //~^ ERROR thread-local statics cannot be accessed at compile-time
-    //~| ERROR cannot refer to statics by value
 }
 
 fn main() {}

src/test/compile-fail/issue-17450.rs renamed to src/test/run-pass/issue-17450.rs

@@ -11,9 +11,6 @@
 #![allow(dead_code, warnings)]
 
 static mut x: isize = 3;
-static mut y: isize = unsafe {
-    x
-//~^ ERROR cannot refer to other statics by value, use the address-of operator or a constant instea
-};
+static mut y: isize = unsafe { x };
 
 fn main() {}

src/test/run-pass/issue-17718-borrow-interior.rs

@@ -10,12 +10,18 @@
 
 struct S { a: usize }
 
-static A: S  = S { a: 3 };
+static A: S = S { a: 3 };
 static B: &'static usize = &A.a;
 static C: &'static usize = &(A.a);
 
 static D: [usize; 1] = [1];
 static E: usize = D[0];
 static F: &'static usize = &D[0];
 
-fn main() {}
+fn main() {
+    assert_eq!(*B, A.a);
+    assert_eq!(*B, A.a);
+
+    assert_eq!(E, D[0]);
+    assert_eq!(*F, D[0]);
+}

src/test/compile-fail/issue-34194.rs renamed to src/test/run-pass/issue-34194.rs

@@ -16,6 +16,5 @@ struct A {
 
 static B: &'static A = &A { a: &() };
 static C: &'static A = &B;
-//~^ ERROR cannot refer to other statics by value
 
 fn main() {}

src/test/compile-fail/issue-6991.rs renamed to src/test/run-pass/issue-6991.rs

@@ -10,6 +10,5 @@
 
 static x: &'static usize = &1;
 static y: usize = *x;
-//~^ ERROR cannot refer to other statics by value,
-//         use the address-of operator or a constant instead
+
 fn main() {}