[llvm] r306001 - [Testing/Support] Remove the const_cast in TakeExpected

[Pavel Labath via llvm-commits]

Author: labath
Date: Thu Jun 22 08:11:50 2017
New Revision: 306001

URL: http://llvm.org/viewvc/llvm-project?rev=306001&view=rev
Log:
[Testing/Support] Remove the const_cast in TakeExpected

Summary:
The const_cast in the "const" version of TakeExpected was quite
dangerous, as the function does indeed modify the apparently const
argument.

I assume the reason the const overload was added was to make the
function bind to xvalues(temporaries). That can be also achieved with
rvalue references, so I use that instead.

Using the ASSERT macros on const Expected objects will now become
illegal, but I believe that is correct, as it is not actually possible
to inspect the error stored in an Expected object without modifying it.

Reviewers: zturner, chandlerc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D34405

Modified:
    llvm/trunk/include/llvm/Testing/Support/Error.h

Modified: llvm/trunk/include/llvm/Testing/Support/Error.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Testing/Support/Error.h?rev=306001&r1=306000&r2=306001&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Testing/Support/Error.h (original)
+++ llvm/trunk/include/llvm/Testing/Support/Error.h Thu Jun 22 08:11:50 2017
@@ -30,8 +30,8 @@ template <typename T> ExpectedHolder<T>
   return Result;
 }
 
-template <typename T> ExpectedHolder<T> TakeExpected(const Expected<T> &Exp) {
-  return TakeExpected(const_cast<Expected<T> &>(Exp));
+template <typename T> ExpectedHolder<T> TakeExpected(Expected<T> &&Exp) {
+  return TakeExpected(Exp);
 }
 } // namespace detail