Fix test case harder (cc #9629)

Author: nikomatsakis

src/librustc/middle/borrowck/doc.rs

@@ -215,6 +215,24 @@ of this rule: there are comments in the borrowck source referencing
 these names, so that you can cross reference to find the actual code
 that corresponds to the formal rule.
 
+### Invariants
+
+I want to collect, at a high-level, the invariants the borrow checker
+maintains. I will give them names and refer to them throughout the
+text. Together these invariants are crucial for the overall soundness
+of the system.
+
+**Mutability requires uniqueness.** To mutate a path
+
+**Unique mutability.** There is only one *usable* mutable path to any
+given memory at any given time. This implies that when claiming memory
+with an expression like `p = &mut x`, the compiler must guarantee that
+the borrowed value `x` can no longer be mutated so long as `p` is
+live. (This is done via restrictions, read on.)
+
+**.**
+
+
 ### The `gather_loans` pass
 
 We start with the `gather_loans` pass, which walks the AST looking for

src/test/run-pass/borrowck-borrow-of-mut-base-ptr-safe.rs

@@ -21,5 +21,5 @@ fn foo<'a>(mut t0: &'a mut int,
     let r: &int = &*t0; // ...after all, could do same thing directly.
 }
 
-fn main() {
+pub fn main() {
 }

src/test/run-pass/borrowck-freeze-frozen-mut.rs

@@ -30,7 +30,7 @@ pub fn main() {
         assert_eq!(*index1, 2);
         assert_eq!(*index2, 3);
     }
-    assert_eq!(data[0], 1);
+    assert_eq!(data[0], 5);
     assert_eq!(data[1], 2);
     assert_eq!(data[2], 3);
 }