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yaml
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r: 24462
b: refs/heads/master
c: cb4c747
h: refs/heads/master
v: v3

Author: graydon

[refs]

@@ -1,5 +1,5 @@
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-refs/heads/master: 6c2c6947256db3841ceb3253ebace259a72dd917
+refs/heads/master: cb4c747e9f6b51f8e44caab27ca376b59df3a56d
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: cd6f24f9d14ac90d167386a56e7a6ac1f0318195
 refs/heads/try: ffbe0e0e00374358b789b0037bcb3a577cd218be

trunk/doc/rust.md

@@ -1468,6 +1468,25 @@ structure of expressions. Blocks themselves are expressions, so the nesting
 sequence of block, statement, expression, and block can repeatedly nest to an
 arbitrary depth.
 
+#### Lvalues, rvalues and temporaries
+
+Expressions are divided into two main categories: _lvalues_ and _rvalues_.
+Likewise within each expression, sub-expressions may occur in _lvalue context_ or _rvalue context_.
+The evaluation of an expression depends both on its own category and the context it occurs within.
+
+Path, field and index expressions are lvalues.
+All other expressions are rvalues.
+
+The left operand of an assignment expression and the operand of the borrow operator are lvalue contexts.
+All other expression contexts are rvalue contexts.
+
+When an lvalue is evaluated in an _lvalue context_, it denotes a memory location;
+when evaluated in an _rvalue context_, it denotes the value held _in_ that memory location.
+
+When an rvalue is used in lvalue context, a temporary un-named lvalue is created and used instead.
+A temporary's lifetime equals the largest lifetime of any borrowed pointer that points to it.
+
+
 ### Literal expressions
 
 A _literal expression_ consists of one of the [literal](#literals)