Merge pull request #289 from gregheo/fix-optionals-docs-comment

Fix docs and comments around optional intrinsics

Author: lattner

docs/archive/LangRef.html

@@ -1295,10 +1295,13 @@ <h3 id="type-optional">Optional Types</h3>
           <code>T?</code>.</li>
       </ul>
       To support these intrinsic use cases, the library is required to
-      provide four functions with these exact signatures:
+      provide functions with these exact signatures:
       <ul>
-        <li><code>func _preconditionOptionalHasValue<T>(inout v : T?)</code>
+        <li><code>func _doesOptionalHaveValueAsBool<T>(v : T?) -> Bool</code></li>
+        <li><code>func _diagnoseUnexpectedNilOptional()</code></li>
         <li><code>func _getOptionalValue<T>(v : T?) -> T</code></li>
+        <li><code>func _injectValueIntoOptional<T>(v : T) -> T?</code></li>
+        <li><code>func _injectNothingIntoOptional<T>() -> T?</code></li>
       </ul>
     </p>
 
@@ -1317,7 +1320,7 @@ <h3 id="type-optional">Optional Types</h3>
       var b : Int? = .None
 
       <i>// Declare an array of optionals:</i>
-      var c : Int?[] = new Int?[4]
+      var c : [Int?] = [10, nil, 42]
     </pre>
 
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lib/SILGen/SILGenFunction.h

@@ -810,7 +810,8 @@ class LLVM_LIBRARY_VISIBILITY SILGenFunction
   /// The result is a Builtin.Int1.
   SILValue emitDoesOptionalHaveValue(SILLocation loc, SILValue addrOrValue);
 
-  /// \brief Emit a call to the library intrinsic _preconditionOptionalHasValue.
+  /// \brief Emit a switch_enum to call the library intrinsic
+  /// _diagnoseUnexpectedNilOptional if the optional has no value.
   void emitPreconditionOptionalHasValue(SILLocation loc, SILValue addr);
 
   /// \brief Emit a call to the library intrinsic _getOptionalValue