[Support] Add a StringError convenience class to Error.h

StringError can be used to represent Errors that aren't recoverable based on
the error type, but that have a useful error message that can be reported to
the user or logged.

llvm-svn: 270948

1 files changed, 16 insertions, 0 deletions

diff --git a/llvm/unittests/Support/ErrorTest.cpp b/llvm/unittests/Support/ErrorTest.cpp
index c2a1673f42d..919bce53860 100644
--- a/llvm/unittests/Support/ErrorTest.cpp
+++ b/llvm/unittests/Support/ErrorTest.cpp
@@ -8,6 +8,8 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Support/Error.h"
+
+#include "llvm/ADT/Twine.h"
 #include "llvm/Support/Errc.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "gtest/gtest.h"
@@ -376,6 +378,20 @@ TEST(Error, CatchErrorFromHandler) {
       << "Failed to handle Error returned from handleErrors.";
 }
 
+TEST(Error, StringError) {
+  std::string Msg;
+  raw_string_ostream S(Msg);
+  logAllUnhandledErrors(make_error<StringError>("foo" + Twine(42),
+                                                unconvertibleErrorCode()),
+                        S, "");
+  EXPECT_EQ(S.str(), "foo42\n") << "Unexpected StringError log result";
+
+  auto EC =
+    errorToErrorCode(make_error<StringError>("", errc::invalid_argument));
+  EXPECT_EQ(EC, errc::invalid_argument)
+    << "Failed to convert StringError to error_code.";
+}
+
 // Test that the ExitOnError utility works as expected.
 TEST(Error, ExitOnError) {
   ExitOnError ExitOnErr;