Test that we correctly handle reversion of line splicing etc in raw string

literals. As suggested by Sean Silva.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@172694 91177308-0d34-0410-b5e6-96231b3b80d8

test/CXX/lex/lex.pptoken/p3-0x.cpp

@@ -9,3 +9,7 @@ template void f<::b>();
 
 #define x a<:: ## : b :>
 int d = x; // expected-error {{pasting formed ':::', an invalid preprocessing token}} expected-error {{expected unqualified-id}}
+
+const char xs[] = R"(\
+??=\U0000)";
+static_assert(sizeof(xs) == 12, "did not revert all changes");