Support/MemoryBuffer: Replace all uses of std::string *ErrMsg with error_code &ec. And fix clients.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121379 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/SourceMgr.cpp b/lib/Support/SourceMgr.cpp
index 0dc1331..f53169a 100644
--- a/lib/Support/SourceMgr.cpp
+++ b/lib/Support/SourceMgr.cpp
@@ -17,6 +17,7 @@
 #include "llvm/Support/SourceMgr.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/system_error.h"
 using namespace llvm;
 
 namespace {
@@ -48,13 +49,13 @@
 /// ~0, otherwise it returns the buffer ID of the stacked file.
 unsigned SourceMgr::AddIncludeFile(const std::string &Filename,
                                    SMLoc IncludeLoc) {
-
-  MemoryBuffer *NewBuf = MemoryBuffer::getFile(Filename.c_str());
+  error_code ec;
+  MemoryBuffer *NewBuf = MemoryBuffer::getFile(Filename.c_str(), ec);
 
   // If the file didn't exist directly, see if it's in an include path.
   for (unsigned i = 0, e = IncludeDirectories.size(); i != e && !NewBuf; ++i) {
     std::string IncFile = IncludeDirectories[i] + "/" + Filename;
-    NewBuf = MemoryBuffer::getFile(IncFile.c_str());
+    NewBuf = MemoryBuffer::getFile(IncFile.c_str(), ec);
   }
 
   if (NewBuf == 0) return ~0U;