Respond to code review feedback and fix tidy

Author: wesleywiser

src/librustc_mir/interpret/eval_context.rs

@@ -135,7 +135,9 @@ impl<'tcx, Tag: Copy + 'static> LocalState<'tcx, Tag> {
     pub fn access(&self) -> InterpResult<'tcx, Operand<Tag>> {
         match self.value {
             LocalValue::Dead => throw_unsup!(DeadLocal),
-            LocalValue::Uninitialized => throw_unsup!(UninitializedLocal),
+            LocalValue::Uninitialized =>
+                // this is reachable from ConstProp
+                throw_unsup!(UninitializedLocal),
             LocalValue::Live(val) => Ok(val),
         }
     }

src/librustc_mir/transform/const_prop.rs

@@ -569,11 +569,15 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
                     base: PlaceBase::Local(local),
                     projection: box [],
                 } = *place {
-                    if let Some(value) = self.const_prop(rval, place_layout, statement.source_info, place) {
+                    if let Some(value) = self.const_prop(rval,
+                                                         place_layout,
+                                                         statement.source_info,
+                                                         place) {
                         trace!("checking whether {:?} can be stored to {:?}", value, local);
                         if self.can_const_prop[local] {
                             trace!("storing {:?} to {:?}", value, local);
-                            assert!(self.get_const(local).is_none() || self.get_const(local) == Some(value));
+                            assert!(self.get_const(local).is_none() ||
+                                    self.get_const(local) == Some(value));
                             self.set_const(local, value);
 
                             if self.should_const_prop() {
@@ -587,19 +591,22 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
                     }
                 }
             }
-        } else if let StatementKind::StorageLive(local) = statement.kind {
-            if self.can_const_prop[local] {
-                let frame = self.ecx.frame_mut();
-
-                frame.locals[local].value = LocalValue::Uninitialized;
-            }
-        } else if let StatementKind::StorageDead(local) = statement.kind {
-            if self.can_const_prop[local] {
-                let frame = self.ecx.frame_mut();
-
-                frame.locals[local].value = LocalValue::Dead;
+        } else {
+            match statement.kind {
+                StatementKind::StorageLive(local) |
+                StatementKind::StorageDead(local) if self.can_const_prop[local] => {
+                    let frame = self.ecx.frame_mut();
+                    frame.locals[local].value =
+                        if let StatementKind::StorageLive(_) = statement.kind {
+                            LocalValue::Uninitialized
+                        } else {
+                            LocalValue::Dead
+                        };
+                }
+                _ => {}
             }
         }
+
         self.super_statement(statement, location);
     }
 

src/test/ui/consts/const-prop-read-static-in-const.rs

@@ -0,0 +1,12 @@
+// compile-flags: -Zunleash-the-miri-inside-of-you
+
+#![allow(dead_code)]
+
+const TEST: u8 = MY_STATIC;
+//~^ skipping const checks
+//~| ERROR any use of this value will cause an error
+
+static MY_STATIC: u8 = 4;
+
+fn main() {
+}

src/test/ui/consts/const-prop-read-static-in-const.stderr

@@ -0,0 +1,18 @@
+warning: skipping const checks
+  --> $DIR/const-prop-read-static-in-const.rs:5:18
+   |
+LL | const TEST: u8 = MY_STATIC;
+   |                  ^^^^^^^^^
+
+error: any use of this value will cause an error
+  --> $DIR/const-prop-read-static-in-const.rs:5:18
+   |
+LL | const TEST: u8 = MY_STATIC;
+   | -----------------^^^^^^^^^-
+   |                  |
+   |                  tried to read from a static during const evaluation
+   |
+   = note: `#[deny(const_err)]` on by default
+
+error: aborting due to previous error
+