[llvm] r264238 - [Support] Add conversions between Expected<T> and ErrorOr<T>.

[Lang Hames via llvm-commits]

Author: lhames
Date: Wed Mar 23 21:00:10 2016
New Revision: 264238

URL: http://llvm.org/viewvc/llvm-project?rev=264238&view=rev
Log:
[Support] Add conversions between Expected<T> and ErrorOr<T>.

More utilities to help with std::error_code -> Error transitions.


Modified:
    llvm/trunk/include/llvm/Support/Error.h
    llvm/trunk/unittests/Support/ErrorTest.cpp

Modified: llvm/trunk/include/llvm/Support/Error.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Error.h?rev=264238&r1=264237&r2=264238&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Support/Error.h (original)
+++ llvm/trunk/include/llvm/Support/Error.h Wed Mar 23 21:00:10 2016
@@ -753,6 +753,22 @@ inline std::error_code errorToErrorCode(
   return EC;
 }
 
+/// Convert an ErrorOr<T> to an Expected<T>.
+template <typename T>
+Expected<T> errorOrToExpected(ErrorOr<T> &&EO) {
+  if (auto EC = EO.getError())
+    return errorCodeToError(EC);
+  return std::move(*EO);
+}
+
+/// Convert an Expected<T> to an ErrorOr<T>.
+template <typename T>
+ErrorOr<T> expectedToErrorOr(Expected<T> &&E) {
+  if (auto Err = E.takeError())
+    return errorToErrorCode(std::move(Err));
+  return std::move(*E);
+}
+
 /// Helper for check-and-exit error handling.
 ///
 /// For tool use only. NOT FOR USE IN LIBRARY CODE.

Modified: llvm/trunk/unittests/Support/ErrorTest.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/unittests/Support/ErrorTest.cpp?rev=264238&r1=264237&r2=264238&view=diff
==============================================================================
--- llvm/trunk/unittests/Support/ErrorTest.cpp (original)
+++ llvm/trunk/unittests/Support/ErrorTest.cpp Wed Mar 23 21:00:10 2016
@@ -416,7 +416,7 @@ TEST(Error, ExpectedCovariance) {
   A2 = Expected<std::unique_ptr<D>>(nullptr);
 }
 
-TEST(Error, ECError) {
+TEST(Error, ErrorCodeConversions) {
   // Round-trip a success value to check that it converts correctly.
   EXPECT_EQ(errorToErrorCode(errorCodeToError(std::error_code())),
             std::error_code())
@@ -427,6 +427,29 @@ TEST(Error, ECError) {
             errc::invalid_argument)
       << "std::error_code error value should round-trip via Error "
          "conversions";
+
+  // Round-trip a success value through ErrorOr/Expected to check that it
+  // converts correctly.
+  {
+    auto Orig = ErrorOr<int>(42);
+    auto RoundTripped =
+      expectedToErrorOr(errorOrToExpected(ErrorOr<int>(42)));
+    EXPECT_EQ(*Orig, *RoundTripped)
+      << "ErrorOr<T> success value should round-trip via Expected<T> "
+         "conversions.";
+  }
+
+  // Round-trip a failure value through ErrorOr/Expected to check that it
+  // converts correctly.
+  {
+    auto Orig = ErrorOr<int>(errc::invalid_argument);
+    auto RoundTripped =
+      expectedToErrorOr(
+          errorOrToExpected(ErrorOr<int>(errc::invalid_argument)));
+    EXPECT_EQ(Orig.getError(), RoundTripped.getError())
+      << "ErrorOr<T> failure value should round-trip via Expected<T> "
+         "conversions.";
+  }
 }
 
 } // end anon namespace