Check type of place base (not projection) for Freeze in IndirectlyMutableLocals

src/librustc_mir/dataflow/impls/indirect_mutation.rs

@@ -104,15 +104,17 @@ impl<'tcx> TransferFunction<'_, '_, 'tcx> {
         kind: mir::BorrowKind,
         borrowed_place: &mir::Place<'tcx>,
     ) -> bool {
-        let borrowed_ty = borrowed_place.ty(self.body, self.tcx).ty;
+        let base_ty = borrowed_place.base.ty(self.body).ty;
 
         // Zero-sized types cannot be mutated, since there is nothing inside to mutate.
         //
         // FIXME: For now, we only exempt arrays of length zero. We need to carefully
         // consider the effects before extending this to all ZSTs.
-        if let ty::Array(_, len) = borrowed_ty.kind {
-            if len.try_eval_usize(self.tcx, self.param_env) == Some(0) {
-                return false;
+        if borrowed_place.projection.is_empty() {
+            if let ty::Array(_, len) = base_ty.kind {
+                if len.try_eval_usize(self.tcx, self.param_env) == Some(0) {
+                    return false;
+                }
             }
         }
 
@@ -122,7 +124,7 @@ impl<'tcx> TransferFunction<'_, '_, 'tcx> {
             | mir::BorrowKind::Shared
             | mir::BorrowKind::Shallow
             | mir::BorrowKind::Unique
-            => !borrowed_ty.is_freeze(self.tcx, self.param_env, DUMMY_SP),
+            => !base_ty.is_freeze(self.tcx, self.param_env, DUMMY_SP),
         }
     }
 }

src/librustc_mir/transform/rustc_peek.rs

@@ -276,7 +276,7 @@ impl<'tcx> RustcPeekAt<'tcx> for IndirectlyMutableLocals<'_, 'tcx> {
         flow_state: &BitSet<Local>,
         call: PeekCall,
     ) {
-        warn!("peek_at: place={:?}", place);
+        trace!("peek_at: place={:?}", place);
         let local = match place {
             mir::Place { base: mir::PlaceBase::Local(l), projection: box [] } => *l,
             _ => {

src/test/ui/mir-dataflow/indirect-mutation-1.rs

@@ -0,0 +1,33 @@
+#![feature(core_intrinsics, rustc_attrs)]
+
+use std::cell::Cell;
+use std::intrinsics::rustc_peek;
+
+#[rustc_mir(rustc_peek_indirectly_mutable, stop_after_dataflow)]
+pub fn mut_ref(flag: bool) -> i32 {
+    let mut i = 0;
+    let mut cell = Cell::new(0);
+
+    if flag {
+        let p = &mut i;
+        unsafe { rustc_peek(i) };
+        *p = 1;
+
+        let p = &cell;
+        unsafe { rustc_peek(cell) };
+        p.set(2);
+    } else {
+        unsafe { rustc_peek(i) };    //~ ERROR rustc_peek: bit not set
+        unsafe { rustc_peek(cell) }; //~ ERROR rustc_peek: bit not set
+
+        let p = &mut cell;
+        unsafe { rustc_peek(cell) };
+        *p = Cell::new(3);
+    }
+
+    unsafe { rustc_peek(i) };
+    unsafe { rustc_peek(cell) };
+    i + cell.get()
+}
+
+fn main() {}

src/test/ui/mir-dataflow/indirect-mutation-1.stderr

@@ -0,0 +1,16 @@
+error: rustc_peek: bit not set
+  --> $DIR/indirect-mutation-1.rs:20:18
+   |
+LL |         unsafe { rustc_peek(i) };
+   |                  ^^^^^^^^^^^^^
+
+error: rustc_peek: bit not set
+  --> $DIR/indirect-mutation-1.rs:21:18
+   |
+LL |         unsafe { rustc_peek(cell) };
+   |                  ^^^^^^^^^^^^^^^^
+
+error: stop_after_dataflow ended compilation
+
+error: aborting due to 3 previous errors
+

src/test/ui/mir-dataflow/indirect-mutation-2.rs

@@ -0,0 +1,30 @@
+#![feature(core_intrinsics, rustc_attrs)]
+
+use std::cell::Cell;
+use std::intrinsics::rustc_peek;
+
+struct Arr {
+    inner: [Cell<i32>; 0],
+    _peek: (),
+}
+
+// Zero-sized arrays are never mutable.
+#[rustc_mir(rustc_peek_indirectly_mutable, stop_after_dataflow)]
+pub fn zst(flag: bool) {
+    {
+        let mut arr: [i32; 0] = [];
+        let s: &mut [i32] = &mut arr;
+        unsafe { rustc_peek(arr) }; //~ ERROR rustc_peek: bit not set
+    }
+
+    {
+        let arr: [Cell<i32>; 0] = [];
+        let s: &[Cell<i32>] = &arr;
+        unsafe { rustc_peek(arr) }; //~ ERROR rustc_peek: bit not set
+
+        let ss = &s;
+        unsafe { rustc_peek(arr) }; //~ ERROR rustc_peek: bit not set
+    }
+}
+
+fn main() {}

src/test/ui/mir-dataflow/indirect-mutation-2.stderr

@@ -0,0 +1,22 @@
+error: rustc_peek: bit not set
+  --> $DIR/indirect-mutation-2.rs:17:18
+   |
+LL |         unsafe { rustc_peek(arr) };
+   |                  ^^^^^^^^^^^^^^^
+
+error: rustc_peek: bit not set
+  --> $DIR/indirect-mutation-2.rs:23:18
+   |
+LL |         unsafe { rustc_peek(arr) };
+   |                  ^^^^^^^^^^^^^^^
+
+error: rustc_peek: bit not set
+  --> $DIR/indirect-mutation-2.rs:26:18
+   |
+LL |         unsafe { rustc_peek(arr) };
+   |                  ^^^^^^^^^^^^^^^
+
+error: stop_after_dataflow ended compilation
+
+error: aborting due to 4 previous errors
+

src/test/ui/mir-dataflow/indirect-mutation-offset.rs

@@ -12,14 +12,17 @@ struct PartialInteriorMut {
 }
 
 #[rustc_mir(rustc_peek_indirectly_mutable,stop_after_dataflow)]
-#[rustc_mir(borrowck_graphviz_postflow="indirect.dot")]
 const BOO: i32 = {
     let x = PartialInteriorMut {
         zst: [],
         cell: UnsafeCell::new(0),
     };
 
-    let p_zst: *const _ = &x.zst ; // Doesn't cause `x` to get marked as indirectly mutable.
+    unsafe { rustc_peek(x) }; //~ ERROR rustc_peek: bit not set
+
+    let p_zst: *const _ = &x.zst ;
+
+    unsafe { rustc_peek(x) };
 
     let rmut_cell = unsafe {
         // Take advantage of the fact that `zst` and `cell` are at the same location in memory.
@@ -30,9 +33,9 @@ const BOO: i32 = {
         &mut *pmut_cell
     };
 
-    *rmut_cell = 42;  // Mutates `x` indirectly even though `x` is not marked indirectly mutable!!!
+    *rmut_cell = 42;
     let val = *rmut_cell;
-    unsafe { rustc_peek(x) }; //~ ERROR rustc_peek: bit not set
+    unsafe { rustc_peek(x) };
 
     val
 };

src/test/ui/mir-dataflow/indirect-mutation-offset.stderr

@@ -1,5 +1,5 @@
 error: rustc_peek: bit not set
-  --> $DIR/indirect-mutation-offset.rs:35:14
+  --> $DIR/indirect-mutation-offset.rs:21:14
    |
 LL |     unsafe { rustc_peek(x) };
    |              ^^^^^^^^^^^^^