[Support] Add a free toString function for Error

toString() consumes an Error and returns a string representation of its
contents. This commit also adds a message() method to ErrorInfoBase for
convenience.

Differential Revision: http://reviews.llvm.org/D19883

llvm-svn: 268465

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/unittests/Support/ErrorTest.cpp b/llvm/unittests/Support/ErrorTest.cpp
index f7e3b398c87..c2a1673f42d 100644
--- a/llvm/unittests/Support/ErrorTest.cpp
+++ b/llvm/unittests/Support/ErrorTest.cpp
@@ -544,4 +544,23 @@ TEST(Error, ErrorCodeConversions) {
   }
 }
 
+// Test that error messages work.
+TEST(Error, ErrorMessage) {
+  EXPECT_EQ(toString(Error::success()).compare(""), 0);
+
+  Error E1 = make_error<CustomError>(0);
+  EXPECT_EQ(toString(std::move(E1)).compare("CustomError { 0}"), 0);
+
+  Error E2 = make_error<CustomError>(0);
+  handleAllErrors(std::move(E2), [](const CustomError &CE) {
+    EXPECT_EQ(CE.message().compare("CustomError { 0}"), 0);
+  });
+
+  Error E3 = joinErrors(make_error<CustomError>(0), make_error<CustomError>(1));
+  EXPECT_EQ(toString(std::move(E3))
+                .compare("CustomError { 0}\n"
+                         "CustomError { 1}"),
+            0);
+}
+
 } // end anon namespace