Merge branch 'master' of https://github.com/thepowersgang/mrustc

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diff --git a/Notes/BorrowChecker.md b/Notes/BorrowChecker.md
index 78b46ff5..d01fcb40 100644
--- a/Notes/BorrowChecker.md
+++ b/Notes/BorrowChecker.md
@@ -1,3 +1,25 @@
+
+Lifetime Annotations
+====================
+
+Problems
+--------
+
+Higher-ranked bounds (lifetimes) can be nested, and typecheck/inferrence can change that nesting after resolve
+- Potential solution: each HRB block (`for<...>`) is numbered within one of three scopes, the impl scope, item scope, and body scope.
+  - Impl scope is for bounds that are visible for the entire `impl` or type block
+  - Item scope is for bounds visible within the current impl item (`fn`, `type`, ...)
+  - Body scope is for bounds within the body of a function (e.g. in type annotations)
+  - Each of these scopes specifies a prefix to the binding IDs, similar to how currently there's three prefixes for generics (impl, item, placeholder)
+
+Region inferrence
+- To what extent does type inferrene play into lifetime inferrence? Can lifetimes be inferred as a second pass after
+  types are concretely known, or do they play into each other?
+
+
+Notes on Borrowck
+=================
+
 - On borrow, calculate lifetime of asignment (using existing lifetime code)
   - Ignore reborrows?
 - Visit all statements in that lifetime and locate places where the borrow is propagated/stored